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McClean ZJ, Young A, Pohl AJ, Fine NM, Burr JF, MacInnis M, Aboodarda SJ. Blood flow restriction during high-intensity interval cycling exacerbates psychophysiological responses to a greater extent in females than males. J Appl Physiol (1985) 2023; 134:596-609. [PMID: 36701480 DOI: 10.1152/japplphysiol.00567.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
This study aimed to characterize neuromuscular, perceptual, and cardiorespiratory responses to high-intensity interval training (HIIT) with superimposed blood flow restriction in males and females. Twenty-four, healthy individuals (n = 12 females) completed two cycling HIIT protocols to task failure (1-min work phases at 90% of peak power output interspersed by 1-min rest phases). The blood flow restriction (BFR) and control (CON) protocols were identical except for the presence and absence of BFR during rest phases, respectively. The interpolated twitch technique, including maximal voluntary isometric knee extension (MVC) and femoral nerve electrical stimuli, was performed at baseline, every six intervals, and task failure. Perceptual and cardiorespiratory responses were recorded every three intervals and continuously during exercise, respectively. Bayesian inference was used to obtain the joint posterior distribution for all parameters and evidence of an effect was determined via the marginal posterior probability (PP). The BFR shortened task duration by 57.3% compared with CON (PP > 0.99), without a sex difference. The application of BFR exacerbated the rate of decline in neuromuscular measures (MVC and twitch force output), increase of perceptual responses (perceived effort, pain, dyspnea, fatigue), and development of cardiorespiratory parameters (minute ventilation and heart rate), compared with CON (PP > 0.95). In addition, BFR exacerbated the neuromuscular, perceptual, and cardiorespiratory responses to a greater extent in females than males (PP > 0.99). Our results suggest that superimposition of blood flow restriction exacerbates psychophysiological responses to a HIIT protocol to a greater extent in females than males.NEW & NOTEWORTHY To our knowledge, no study has explored sex differences in the neuromuscular, perceptual, and cardiorespiratory indices characterizing exercise tolerance during high-intensity interval training (HIIT) with blood flow restriction (BFR) applied only during rest periods. Our results suggest that BFR elicited a decline in exercise performance that could be attributed to integration of psychophysiological responses. However, this integration was sex-dependent where females demonstrated an exacerbated rate of change in these responses compared with males.
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Affiliation(s)
- Zachary J McClean
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Abbey Young
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Andrew J Pohl
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Nowell M Fine
- Cummings School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jamie F Burr
- College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Martin MacInnis
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Saied J Aboodarda
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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2
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Kissler K, Hurt KJ. The Pathophysiology of Labor Dystocia: Theme with Variations. Reprod Sci 2023; 30:729-742. [PMID: 35817950 PMCID: PMC10388369 DOI: 10.1007/s43032-022-01018-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 06/16/2022] [Indexed: 10/17/2022]
Abstract
Abnormally prolonged labor, or labor dystocia, is a common complication of parturition. It is the indication for about half of unplanned cesarean deliveries in low-risk nulliparous women. Reducing the rate of unplanned cesarean birth in the USA has been a public health priority over the last two decades with limited success. Labor dystocia is a complex disorder due to multiple causes with a common clinical outcome of slow cervical dilation and fetal descent. A better understanding of the pathophysiologic mechanisms of labor dystocia could lead to new clinical opportunities to increase the rate of normal vaginal delivery, reduce cesarean birth rates, and improve maternal and neonatal health. We conducted a literature review of the causes and pathophysiologic mechanisms of labor dystocia. We summarize known mechanisms supported by clinical and experimental data and newer hypotheses with less supporting evidence. We review recent data on uterine preparation for labor, uterine contractility, cervical preparation for labor, maternal obesity, cephalopelvic disproportion, fetal malposition, intrauterine infection, and maternal stress. We also describe current clinical approaches to preventing and managing labor dystocia. The variation in pathophysiologic causes of labor dystocia probably limits the utility of current general treatment options. However, treatments targeting specific underlying etiologies could be more effective. We found that the pathophysiologic basis of labor dystocia is under-researched, offering wide opportunities for translational investigation of individualized labor management, particularly regarding uterine metabolism and fetal position. More precise diagnostic tools and individualized therapies for labor dystocia might lead to better outcomes. We conclude that additional knowledge of parturition physiology coupled with rigorous clinical evaluation of novel biologically directed treatments could improve obstetric quality of care.
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Affiliation(s)
- Katherine Kissler
- College of Nursing, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - K Joseph Hurt
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, 12700 East 19th Avenue, Aurora, CO, 80045, USA.
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, 12700 East 19th Avenue, Mailstop 8613, Aurora, CO, 80045, USA.
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3
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Iannetta D, Zhang J, Murias JM, Aboodarda SJ. Neuromuscular and perceptual mechanisms of fatigue accompanying task failure in response to moderate-, heavy-, severe-, and extreme-intensity cycling. J Appl Physiol (1985) 2022; 133:323-334. [PMID: 35771217 DOI: 10.1152/japplphysiol.00764.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A comprehensive characterization of neuromuscular and perceptual mechanisms of fatigue at task failure following exercise across the entire intensity spectrum is lacking. This study evaluated the extent of peripheral and central fatigue, and corresponding perceptual attributes, at task failure following cycling within the moderate-(MOD), heavy-(HVY), severe-(SVR), and extreme-(EXT) intensity domains. After a ramp-incremental test, eleven young males performed four constant-power output trials to the limit of tolerance (Tlim) at four distinct domain-specific workloads. These trials were preceded and followed by 5-s knee-extension maximal voluntary contractions (MVC) and femoral nerve electrical stimuli to quantify peripheral and central fatigue. Additionally, perceptual measures including ratings of global fatigue, legs pain, dyspnea and perceived effort (RPE) were also collected. At Tlim, reductions in MVC were independent of intensity (P>0.05). However, peripheral fatigue was greater following EXT and SVR and progressively, but distinctively, lower following HVY and MOD (P<0.05). Central fatigue was similar after SVR, HVY, and MOD, but absent after EXT (P<0.05). At Tlim, subjective ratings of global fatigue were progressively higher with lower exercise intensities, while ratings of legs pain and dyspnea were progressively higher with higher exercise intensities. On the other hand, RPE was maximal following HVY, SVR, and EXT, but not MOD. The findings demonstrate that at Tlim the extent of peripheral fatigue is highly domain-specific whereas the extent of central fatigue is not. Sensations such as fatigue, pain, and dyspnea may integrate with mechanisms of sense of effort to determine task failure in a manner specific to each intensity domain.
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Affiliation(s)
- Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jenny Zhang
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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4
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Dos Santos Andrade VF, Cabral LL, Da Silva CK, Villarejo Mayor JJ, Félix Rodacki AL, Lima-Silva AE, Pereira G. The completely recover of quadriceps muscle peripheral fatigue after running in Olympic but not in Sprint triathlon. Eur J Sport Sci 2022; 23:885-895. [PMID: 35502595 DOI: 10.1080/17461391.2022.2072772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
ABSTRACTThis study compared central and peripheral fatigue development between Sprint and Olympic distance triathlon. Fifteen male triathletes performed Sprint and Olympic triathlon simulations in a randomized and counterbalanced order. Central and peripheral fatigue was evaluated from changes in voluntary activation level (VAL) and twitch responses of quadriceps muscle (Qtw,pot), respectively. Qtw,pot reduced from baseline to post-swimming similarly between triathlon simulations (Sprint, -17±11%; Olympic, -13±9%). In post-cycling, Qtw,pot further declined to a similar extent between triathlon distances (Sprint, -31±15%; Olympic, -28±11%). In post-running, Qtw,pot was fully recovered in Olympic triathlon (-4±10%), whereas there was only a partial recovery of Qtw,pot in Sprint triathlon (-20±11%). VAL was not reduced in post-swimming, but reduction was similar between triathlon distances in post-cycling (Sprint, -10±9%; Olympic, -8±8%) and post-running (Sprint, -15±14%; Olympic, -16±8%). In Sprint triathlon, the swimming speed (1.07±0.13 m ·s-1) was above (p<.001) critical speed (1.01±0.14 m ·s-1), the cycling power (179.7±27.2W) was below the respiratory compensation point (216.3±27.8W, p<.001) and running speed (13.7±1.05km·h-1) similar to the respiratory compensation point (13.2±0.70 km·h-1, p=.124). In Olympic triathlon, swimming speed (1.03±0.13m·s-1) was similar to critical speed (p=.392), and both cycling power (165.3±27.3W) and running speed (12.6±1.05km·h-1) were below the respiratory compensation point (p≤.007). In conclusion, peripheral fatigue progressed until post-cycling regardless of triathlon distances. However, peripheral fatigue was fully recovered after running in Olympic but not in Sprint triathlon. The central fatigue started in post-cycling and progressed until post-running regardless of triathlon distances.
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Affiliation(s)
- Vinicius Ferreira Dos Santos Andrade
- Department of Physical Education, Federal University of Parana (UFPR), Curitiba, Parana, BRAZIL.,Physical Education and Sports Center, Federal University of Parana (UFPR), Curitiba, Parana, BRAZIL
| | - Luana Loss Cabral
- Department of Physical Education, Federal University of Parana (UFPR), Curitiba, Parana, BRAZIL
| | | | | | | | - Adriano E Lima-Silva
- Department of Physical Education, Federal University of Parana (UFPR), Curitiba, Parana, BRAZIL.,Human Performance Research Group, Technological Federal University of Parana (UTFPR), Curitiba, Parana, BRAZIL
| | - Gleber Pereira
- Department of Physical Education, Federal University of Parana (UFPR), Curitiba, Parana, BRAZIL
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The Role of Taurine in Skeletal Muscle Functioning and Its Potential as a Supportive Treatment for Duchenne Muscular Dystrophy. Metabolites 2022; 12:metabo12020193. [PMID: 35208266 PMCID: PMC8879184 DOI: 10.3390/metabo12020193] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
Taurine (2-aminoethanesulfonic acid) is required for ensuring proper muscle functioning. Knockout of the taurine transporter in mice results in low taurine concentrations in the muscle and associates with myofiber necrosis and diminished exercise capacity. Interestingly, regulation of taurine and its transporter is altered in the mdx mouse, a model for Duchenne Muscular Dystrophy (DMD). DMD is a genetic disorder characterized by progressive muscle degeneration and weakness due to the absence of dystrophin from the muscle membrane, causing destabilization and contraction-induced muscle cell damage. This review explores the physiological role of taurine in skeletal muscle and the consequences of a disturbed balance in DMD. Its potential as a supportive treatment for DMD is also discussed. In addition to genetic correction, that is currently under development as a curative treatment, taurine supplementation has the potential to reduce muscle inflammation and improve muscle strength in patients.
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6
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Noakes TD. What Is the Evidence That Dietary Macronutrient Composition Influences Exercise Performance? A Narrative Review. Nutrients 2022; 14:862. [PMID: 35215511 PMCID: PMC8875928 DOI: 10.3390/nu14040862] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 01/06/2023] Open
Abstract
The introduction of the needle muscle biopsy technique in the 1960s allowed muscle tissue to be sampled from exercising humans for the first time. The finding that muscle glycogen content reached low levels at exhaustion suggested that the metabolic cause of fatigue during prolonged exercise had been discovered. A special pre-exercise diet that maximized pre-exercise muscle glycogen storage also increased time to fatigue during prolonged exercise. The logical conclusion was that the athlete's pre-exercise muscle glycogen content is the single most important acutely modifiable determinant of endurance capacity. Muscle biochemists proposed that skeletal muscle has an obligatory dependence on high rates of muscle glycogen/carbohydrate oxidation, especially during high intensity or prolonged exercise. Without this obligatory carbohydrate oxidation from muscle glycogen, optimum muscle metabolism cannot be sustained; fatigue develops and exercise performance is impaired. As plausible as this explanation may appear, it has never been proven. Here, I propose an alternate explanation. All the original studies overlooked one crucial finding, specifically that not only were muscle glycogen concentrations low at exhaustion in all trials, but hypoglycemia was also always present. Here, I provide the historical and modern evidence showing that the blood glucose concentration-reflecting the liver glycogen rather than the muscle glycogen content-is the homeostatically-regulated (protected) variable that drives the metabolic response to prolonged exercise. If this is so, nutritional interventions that enhance exercise performance, especially during prolonged exercise, will be those that assist the body in its efforts to maintain the blood glucose concentration within the normal range.
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Affiliation(s)
- Timothy David Noakes
- Department of Applied Design, Cape Peninsula University of Technology, Cape Town 8000, South Africa
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7
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Gollie JM, Patel SS, Harris-Love MO, Cohen SD, Blackman MR. Fatigability and the Role of Neuromuscular Impairments in Chronic Kidney Disease. Am J Nephrol 2022; 53:253-263. [PMID: 35344954 PMCID: PMC9871956 DOI: 10.1159/000523714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/16/2022] [Indexed: 01/28/2023]
Abstract
BACKGROUND The combination of neuromuscular impairments plus psychosocial aspects of chronic kidney disease (CKD) may predispose these patients to greater risk for experiencing increased levels of fatigability. There has been extensive clinical and scientific interest in the problem of fatigue in CKD and end-stage kidney disease (ESKD) patients, whereas less attention has been directed to understanding fatigability. Accordingly, the primary purposes of this review are to (1) discuss fatigue and fatigability and their potential interactions in patients with CKD and ESKD, (2) provide evidence for increased fatigability in CKD and ESKD patients, (3) examine how commonly experienced neuromuscular impairments in CKD and ESKD patients may contribute to the severity of performance fatigability, and (4) highlight preliminary evidence on the effects of exercise as a potential clinical treatment for targeting fatigability in this population. SUMMARY Fatigue is broadly defined as a multidimensional construct encompassing a subjective lack of physical and/or mental energy that is perceived by the individual to interfere with usual or desired activities. In contrast, fatigability is conceptualized within the context of physical activity and is quantified as the interactions between reductions in objective measures of performance (i.e., performance fatigability) and perceptual adjustments regulating activity performance (i.e., perceived fatigability). We propose herein a conceptual model to extend current understandings of fatigability by considering the interactions among fatigue, perceived fatigability, and performance fatigability. Neuromuscular impairments reported in patients with CKD and ESKD, including reductions in force capacity, skeletal muscle atrophy, mitochondrial dysfunction, abnormal skeletal muscle excitability, and neurological complications, may each contribute to the greater performance fatigability observed in these patients. KEY MESSAGES Considering the interactions among fatigue, perceived fatigability, and performance fatigability provides a novel conceptual framework to advance the understanding of fatigability in CKD and ESKD patients. Measures of fatigability may provide valuable clinical insights into the overall health status of CKD and ESKD patients. Existing data suggest that CKD and ESKD patients are at greater risk of experiencing increased fatigability, partly due to neuromuscular impairments associated with reduced kidney function. Further investigations are warranted to determine the potential clinical role fatigability measures can play in monitoring the health of CKD and ESKD patients, and in identifying potential treatments targeting fatigability in this patient population.
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Affiliation(s)
- Jared M. Gollie
- Research Service, Washington DC VA Medical Center, Washington, DC, USA;,Department of Health, Human Function and Rehabilitation Sciences, George Washington University, Washington, DC, USA
| | - Samir S. Patel
- Renal Service, Washington DC VA Medical Center, Washington, DC, USA;,Department of Medicine, George Washington University, Washington, DC, USA
| | - Michael O. Harris-Love
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado, Aurora, CO, USA;,Geriatric Research Education and Clinical Center, VA Eastern Colorado Health Care System, Aurora, CO, USA
| | - Scott D. Cohen
- Renal Service, Washington DC VA Medical Center, Washington, DC, USA;,Department of Medicine, George Washington University, Washington, DC, USA
| | - Marc R. Blackman
- Research Service, Washington DC VA Medical Center, Washington, DC, USA;,Department of Medicine, George Washington University, Washington, DC, USA;,Departments of Medicine and Rehabilitation Medicine, Georgetown University, Washington, DC, USA
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8
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Wang J, Zhou Y, Jiang L. Bio-inspired Track-Etched Polymeric Nanochannels: Steady-State Biosensors for Detection of Analytes. ACS NANO 2021; 15:18974-19013. [PMID: 34846138 DOI: 10.1021/acsnano.1c08582] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Bio-inspired polymeric nanochannel (also referred as nanopore)-based biosensors have attracted considerable attention on account of their controllable channel size and shape, multi-functional surface chemistry, unique ionic transport properties, and good robustness for applications. There are already very informative reviews on the latest developments in solid-state artificial nanochannel-based biosensors, however, which concentrated on the resistive-pulse sensing-based sensors for practical applications. The steady-state sensing-based nanochannel biosensors, in principle, have significant advantages over their counterparts in term of high sensitivity, fast response, target analytes with no size limit, and extensive suitable range. Furthermore, among the diverse materials, nanochannels based on polymeric materials perform outstandingly, due to flexible fabrication and wide application. This compressive Review summarizes the recent advances in bio-inspired polymeric nanochannels as sensing platforms for detection of important analytes in living organisms, to meet the high demand for high-performance biosensors for analysis of target analytes, and the potential for development of smart sensing devices. In the future, research efforts can be focused on transport mechanisms in the field of steady-state or resistive-pulse nanochannel-based sensors and on developing precisely size-controlled, robust, miniature and reusable, multi-functional, and high-throughput biosensors for practical applications. Future efforts should aim at a deeper understanding of the principles at the molecular level and incorporating these diverse pore architectures into homogeneous and defect-free multi-channel membrane systems. With the rapid advancement of nanoscience and biotechnology, we believe that many more achievements in nanochannel-based biosensors could be achieved in the near future, serving people in a better way.
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Affiliation(s)
- Jian Wang
- College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, People's Republic of China
| | - Yahong Zhou
- Key Laboratory of Bio-inspired Materials and Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, People's Republic of China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Materials and Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, People's Republic of China
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9
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Grgic J, Pedisic Z, Saunders B, Artioli GG, Schoenfeld BJ, McKenna MJ, Bishop DJ, Kreider RB, Stout JR, Kalman DS, Arent SM, VanDusseldorp TA, Lopez HL, Ziegenfuss TN, Burke LM, Antonio J, Campbell BI. International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance. J Int Soc Sports Nutr 2021; 18:61. [PMID: 34503527 PMCID: PMC8427947 DOI: 10.1186/s12970-021-00458-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Based on a comprehensive review and critical analysis of the literature regarding the effects of sodium bicarbonate supplementation on exercise performance, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Supplementation with sodium bicarbonate (doses from 0.2 to 0.5 g/kg) improves performance in muscular endurance activities, various combat sports, including boxing, judo, karate, taekwondo, and wrestling, and in high-intensity cycling, running, swimming, and rowing. The ergogenic effects of sodium bicarbonate are mostly established for exercise tasks of high-intensity that last between 30 s and 12 min. 2. Sodium bicarbonate improves performance in single- and multiple-bout exercise. 3. Sodium bicarbonate improves exercise performance in both men and women. 4. For single-dose supplementation protocols, 0.2 g/kg of sodium bicarbonate seems to be the minimum dose required to experience improvements in exercise performance. The optimal dose of sodium bicarbonate dose for ergogenic effects seems to be 0.3 g/kg. Higher doses (e.g., 0.4 or 0.5 g/kg) may not be required in single-dose supplementation protocols, because they do not provide additional benefits (compared with 0.3 g/kg) and are associated with a higher incidence and severity of adverse side-effects. 5. For single-dose supplementation protocols, the recommended timing of sodium bicarbonate ingestion is between 60 and 180 min before exercise or competition. 6. Multiple-day protocols of sodium bicarbonate supplementation can be effective in improving exercise performance. The duration of these protocols is generally between 3 and 7 days before the exercise test, and a total sodium bicarbonate dose of 0.4 or 0.5 g/kg per day produces ergogenic effects. The total daily dose is commonly divided into smaller doses, ingested at multiple points throughout the day (e.g., 0.1 to 0.2 g/kg of sodium bicarbonate consumed at breakfast, lunch, and dinner). The benefit of multiple-day protocols is that they could help reduce the risk of sodium bicarbonate-induced side-effects on the day of competition. 7. Long-term use of sodium bicarbonate (e.g., before every exercise training session) may enhance training adaptations, such as increased time to fatigue and power output. 8. The most common side-effects of sodium bicarbonate supplementation are bloating, nausea, vomiting, and abdominal pain. The incidence and severity of side-effects vary between and within individuals, but it is generally low. Nonetheless, these side-effects following sodium bicarbonate supplementation may negatively impact exercise performance. Ingesting sodium bicarbonate (i) in smaller doses (e.g., 0.2 g/kg or 0.3 g/kg), (ii) around 180 min before exercise or adjusting the timing according to individual responses to side-effects, (iii) alongside a high-carbohydrate meal, and (iv) in enteric-coated capsules are possible strategies to minimize the likelihood and severity of these side-effects. 9. Combining sodium bicarbonate with creatine or beta-alanine may produce additive effects on exercise performance. It is unclear whether combining sodium bicarbonate with caffeine or nitrates produces additive benefits. 10. Sodium bicarbonate improves exercise performance primarily due to a range of its physiological effects. Still, a portion of the ergogenic effect of sodium bicarbonate seems to be placebo-driven.
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Affiliation(s)
- Jozo Grgic
- Institute for Health and Sport, Victoria University, Melbourne, Australia.
| | - Zeljko Pedisic
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Bryan Saunders
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR, University of São Paulo, Sao Paulo, Brazil
- Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, Sao Paulo, Brazil
| | - Guilherme G Artioli
- Centre for Bioscience, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | | | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - David J Bishop
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Richard B Kreider
- Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Department of Health & Kinesiology, Texas A&M University, College Station, TX, USA
| | - Jeffrey R Stout
- Physiology of Work and Exercise Response (POWER) Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, USA
| | - Douglas S Kalman
- Nutrion Department, College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale, FL, 33314, USA
- Scientific Affairs. Nutrasource, Guelph, ON, Canada
| | - Shawn M Arent
- Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - Trisha A VanDusseldorp
- Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA
| | - Hector L Lopez
- The Center for Applied Health Sciences, Stow, OH, USA
- Supplement Safety Solutions, Bedford, MA, 01730, USA
| | | | - Louise M Burke
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
| | - Jose Antonio
- Exercise and Sport Science, Nova Southeastern University, Davie, FL, 33314, USA
| | - Bill I Campbell
- Performance & Physique Enhancement Laboratory, University of South Florida, Tampa, FL, 33612, USA
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10
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Maximal muscular power: lessons from sprint cycling. SPORTS MEDICINE-OPEN 2021; 7:48. [PMID: 34268627 PMCID: PMC8282832 DOI: 10.1186/s40798-021-00341-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/29/2021] [Indexed: 02/07/2023]
Abstract
Maximal muscular power production is of fundamental importance to human functional capacity and feats of performance. Here, we present a synthesis of literature pertaining to physiological systems that limit maximal muscular power during cyclic actions characteristic of locomotor behaviours, and how they adapt to training. Maximal, cyclic muscular power is known to be the main determinant of sprint cycling performance, and therefore we present this synthesis in the context of sprint cycling. Cyclical power is interactively constrained by force-velocity properties (i.e. maximum force and maximum shortening velocity), activation-relaxation kinetics and muscle coordination across the continuum of cycle frequencies, with the relative influence of each factor being frequency dependent. Muscle cross-sectional area and fibre composition appear to be the most prominent properties influencing maximal muscular power and the power-frequency relationship. Due to the role of muscle fibre composition in determining maximum shortening velocity and activation-relaxation kinetics, it remains unclear how improvable these properties are with training. Increases in maximal muscular power may therefore arise primarily from improvements in maximum force production and neuromuscular coordination via appropriate training. Because maximal efforts may need to be sustained for ~15-60 s within sprint cycling competition, the ability to attenuate fatigue-related power loss is also critical to performance. Within this context, the fatigued state is characterised by impairments in force-velocity properties and activation-relaxation kinetics. A suppression and leftward shift of the power-frequency relationship is subsequently observed. It is not clear if rates of power loss can be improved with training, even in the presence adaptations associated with fatigue-resistance. Increasing maximum power may be most efficacious for improving sustained power during brief maximal efforts, although the inclusion of sprint interval training likely remains beneficial. Therefore, evidence from sprint cycling indicates that brief maximal muscular power production under cyclical conditions can be readily improved via appropriate training, with direct implications for sprint cycling as well as other athletic and health-related pursuits.
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11
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Hostrup M, Cairns SP, Bangsbo J. Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance. Compr Physiol 2021; 11:1895-1959. [PMID: 34190344 DOI: 10.1002/cphy.c190024] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise causes major shifts in multiple ions (e.g., K+ , Na+ , H+ , lactate- , Ca2+ , and Cl- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K+ , Na+ , and Ca2+ during fatiguing exercise, while changes in gradients for Cl- and Cl- conductance may exert either protective or detrimental effects on fatigue. Myocellular H+ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca2+ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na+ /K+ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K+ and Cl- , respectively via metabolic regulation of the ATP-sensitive K+ channel (KATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.
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Affiliation(s)
- Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Simeon Peter Cairns
- SPRINZ, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand.,Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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12
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Inns TB, McCormick D, Greig CA, Atherton PJ, Phillips BE, Piasecki M. Factors associated with electrical stimulation-induced performance fatigability are dependent upon stimulation location. Exp Physiol 2021; 106:828-836. [PMID: 33638246 DOI: 10.1113/ep089204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 02/23/2021] [Indexed: 12/14/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does peripheral nerve stimulation (PNS) compare with neuromuscular electrical stimulation (NMES) used clinically to reduce muscle atrophy? What is the main finding and its importance? NMES resulted in progressive increases in M-wave duration and delay of muscle relaxation throughout a single stimulation protocol, findings not observed with PNS. This suggests PNS recruits from a wider pool of muscle fibres/motor units, providing a more favourable alternative to NMES for rehabilitation intervention. ABSTRACT Neuromuscular electrical stimulation (NMES) is increasingly viewed as a central tenet to minimise muscle loss during periods of disuse/illness - typically applied directly over a muscle belly. Peripheral nerve stimulation (PNS) is afforded less attention, despite providing a more global contractile stimulus to muscles. We investigated NMES versus PNS in relation to performance fatigability and peripheral contributions to voluntary force capacity. Two fatigue protocols were assessed separately: (1) over-quadriceps NMES and (2) peripheral (femoral) nerve stimulation (PNS). Before and after each session, a maximal voluntary contraction (MVC) was performed to assess force loss. Knee-extensor force was measured throughout to assess contractile function in response to submaximal electrical stimulation, and M-wave features quantified myoelectrical activity. NMES and PNS induced similar voluntary (MVC, NMES: -12 ± 9%, PNS: -10 ± 8%, both P < 0.001) and stimulated (NMES: -45 ± 12%, PNS -27 ± 27%, both P < 0.001) force reductions. Although distinct between protocols, myoelectrical indicators of muscle recruitment (M-wave area and amplitude) and nerve conduction time did not change throughout either protocol. Myoelectrical propagation speed, represented as M-wave duration, and the delay before muscle relaxation began both progressively increased during NMES only (P < 0.05 and P < 0.001, respectively). NMES myoelectrical changes suggested performance fatigability, indicating activation of superficial fibres only, which was not observed with PNS. This suggests PNS recruits a wider pool of muscle fibres and motor units and is a favourable alternative for rehabilitation. Future work should focus on implementing PNS interventions in clinically relevant scenarios such as immobilisation, care homes and critical illness.
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Affiliation(s)
- Thomas B Inns
- Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
| | - Daniel McCormick
- Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
| | - Carolyn A Greig
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.,MRC-Versus Arthritis Research UK Centre for Musculoskeletal Ageing Research, NIHR Birmingham Biomedical Research Centre, University Hospitals Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, UK
| | - Philip J Atherton
- Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
| | - Bethan E Phillips
- Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
| | - Mathew Piasecki
- Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
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13
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Berardi G, Senefeld JW, Hunter SK, Bement MKH. Impact of isometric and concentric resistance exercise on pain and fatigue in fibromyalgia. Eur J Appl Physiol 2021; 121:1389-1404. [PMID: 33616753 DOI: 10.1007/s00421-021-04600-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 01/10/2021] [Indexed: 10/22/2022]
Abstract
PURPOSE The aim of this study was to determine the local and systemic effects of isometric and concentric muscle contractions on experimental pain and performance fatigability in people with and without fibromyalgia. METHODS Forty-seven fibromyalgia (FM: 51.3 ± 12.3 year) and 47 control (CON: 52.5 ± 14.7 year) participants performed submaximal isometric and concentric exercise for 10 min with the right elbow flexors. Assessments before and after exercise included pressure pain thresholds (PPT) of the biceps and quadriceps, central pain summation, self-reported exercising arm and whole-body pain, and maximal voluntary isometric contraction (MVIC) of the right elbow flexors and left handgrip. RESULTS People with FM experienced greater reductions in local fatigue (right elbow flexor MVIC: CON: - 4.0 ± 6.7%, FM: - 9.8 ± 13.8%; p = 0.013) and similar reductions in systemic fatigue (left handgrip MVIC: - 6.5 ± 10.2%; p < 0.001) as CON participants, which were not different by contraction type nor related to baseline clinical pain, perceived fatigue, or reported pain with exercise. Following exercise both groups reported an increase in PPTs at the biceps (pre: 205.5 ± 100.3 kPa, post: 219.0 ± 109.3 kPa, p = 0.004) only and a decrease in central pain summation (pre: 6.8 ± 2.9, post: 6.5 ± 2.9; p = 0.013). FM reported greater exercising arm pain following exercise (CON: 0.7 ± 1.3, FM: 2.9 ± 2.3; p < 0.001), and both groups reported greater arm pain following concentric (isometric: 1.4 ± 2.0, concentric: 2.2 ± 2.9; p = 0.001) than isometric exercise. Neither group reported an increase in whole-body pain following exercise. CONCLUSION People with FM experienced greater performance fatigability in the exercising muscle compared to CON that was not related to central mechanisms of fatigue or pain. These results suggest changes in performance fatigability in FM may be due to differences occurring at the muscular level. TRIAL REGISTRATION #: NCT #: NCT03778385, December 19, 2018, retrospectively registered. IRB#: HR-3035.
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Affiliation(s)
- Giovanni Berardi
- Department of Physical Therapy, Marquette University, 561 N 15 St, Milwaukee, WI, 53233, USA.
| | - Jonathon W Senefeld
- Department of Physical Therapy, Marquette University, 561 N 15 St, Milwaukee, WI, 53233, USA.,Exercise Science Program, Marquette University, Milwaukee, WI, USA.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University, 561 N 15 St, Milwaukee, WI, 53233, USA.,Exercise Science Program, Marquette University, Milwaukee, WI, USA
| | - Marie K Hoeger Bement
- Department of Physical Therapy, Marquette University, 561 N 15 St, Milwaukee, WI, 53233, USA
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14
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Loturco I, De la Fuente C, Bishop C, Nichioka H, Lessio D, Moreno CT, Pereira LA, Carpes FP. Video-based biomechanical analysis of an unexpected Achilles tendon rupture in an Olympic sprinter. J Biomech 2021; 117:110246. [PMID: 33493708 DOI: 10.1016/j.jbiomech.2021.110246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 12/29/2020] [Accepted: 01/03/2021] [Indexed: 11/16/2022]
Abstract
We used image-processing techniques to determine the moment (i.e., image frame) of the Achilles tendon (AT) rupture in an Olympic sprinter. This report may be unique due to the difficulty in conducting motion capture analyses during injury events. Our report includes one female Olympic sprinter, 29 years old (body mass: 56 kg, height: 1.68 m, and body mass index: 19.8 kg/m2) with a high-competitive profile history (2008 and 2012 Olympic Games participation; South American record holder in 100- and 200-m; Pan-American gold medalist in 200-m and 4 × 100-m relay) who suffered a complete AT rupture in the left leg while exercising in the final phase of rehabilitation following an Achilles tendinopathy in the contralateral limb. The greater dorsiflexion found at the moment of the injury and the delayed control of heel position indicated the presence of uncontrolled dorsiflexion, which potentially generated excessive eccentric stress over the tendon and, thus, the AT rupture. Here we discuss the relevance of lower leg alignment, the movements' characteristics, and the history of Achilles tendinopathy in the contralateral leg on the occurrence of the AT rupture.
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Affiliation(s)
- Irineu Loturco
- Nucleus of High Performance in Sport, São Paulo, Brazil; Department of Human Movement Sciences, Federal University of São Paulo, São Paulo, Brazil; University of South Wales, Pontypridd, Wales, United Kingdom
| | - Carlos De la Fuente
- Applied Neuromechanics Research Group, Universidade Federal do Pampa, Uruguaiana, RS, Brazil; Carrera de Kinesiología, Departamento de Cs. de la Salud, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile; Clínica MEDS, Santiago, Chile
| | - Chris Bishop
- Faculty of Science and Technology, London Sports Institute, Middlesex University, London, UK
| | | | | | - Carlos T Moreno
- Department of Orthopedics and Traumatology, Federal University of São Paulo (Unifesp), São Paulo, SP, Brazil
| | - Lucas A Pereira
- Nucleus of High Performance in Sport, São Paulo, Brazil; Department of Human Movement Sciences, Federal University of São Paulo, São Paulo, Brazil
| | - Felipe P Carpes
- Applied Neuromechanics Research Group, Universidade Federal do Pampa, Uruguaiana, RS, Brazil.
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15
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Wang Z, Zhang J, Ma XF, Chang H, Peng X, Xu SH, Wang HP, Gao YF. A Temporal Examination of Cytoplasmic Ca 2 + Levels, Sarcoplasmic Reticulum Ca 2 + Levels, and Ca 2 + -Handling-Related Proteins in Different Skeletal Muscles of Hibernating Daurian Ground Squirrels. Front Physiol 2020; 11:562080. [PMID: 33192559 PMCID: PMC7609816 DOI: 10.3389/fphys.2020.562080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/30/2020] [Indexed: 12/13/2022] Open
Abstract
To explore the possible mechanism of the sarcoplasmic reticulum (SR) in the maintenance of cytoplasmic calcium (Ca2+) homeostasis, we studied changes in cytoplasmic Ca2+, SR Ca2+, and Ca2+-handling proteins of slow-twitch muscle (soleus, SOL), fast-twitch muscle (extensor digitorum longus, EDL), and mixed muscle (gastrocnemius, GAS) in different stages in hibernating Daurian ground squirrels (Spermophilus dauricus). Results showed that the level of cytoplasmic Ca2+ increased and SR Ca2+ decreased in skeletal muscle fiber during late torpor (LT) and inter-bout arousal (IBA), but both returned to summer active levels when the animals aroused from and re-entered into torpor (early torpor, ET), suggesting that intracellular Ca2+ is dynamic during hibernation. The protein expression of ryanodine receptor1 (RyR1) increased in the LT, IBA, and ET groups, whereas the co-localization of calsequestrin1 (CSQ1) and RyR1 in GAS muscle decreased in the LT and ET groups, which may increase the possibility of RyR1 channel-mediated Ca2+ release. Furthermore, calcium pump (SR Ca2+-ATPase 1, SERCA1) protein expression increased in the LT, IBA, and ET groups, and the signaling pathway-related factors of SERCA activity [i.e., β-adrenergic receptor2 protein expression (in GAS), phosphorylation levels of phospholamban (in GAS), and calmodulin kinase2 (in SOL)] all increased, suggesting that these factors may be involved in the up-regulation of SERCA1 activity in different groups. The increased protein expression of Ca2+-binding proteins CSQ1 and calmodulin (CaM) indicated that intracellular free Ca2+-binding ability also increased in the LT, IBA, ET, and POST groups. In brief, changes in cytoplasmic and SR Ca2+ concentrations, SR RyR1 and SERCA1 protein expression levels, and major RyR1 and SERCA1 signaling pathway-related factors were unexpectedly active in the torpor stage when metabolic functions were highly inhibited.
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Affiliation(s)
- Zhe Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China.,College of Life Sciences, Qufu Normal University, Qufu, China
| | - Jie Zhang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Xiu-Feng Ma
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Hui Chang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Xin Peng
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Shen-Hui Xu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Hui-Ping Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
| | - Yun-Fang Gao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China.,Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China
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16
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Nolan J, Mclennan PL, Peoples GE. Forearm isometric fatigue-resistance is enhanced in rock climbers compared to power lifters and aerobically-trained athletes. J Sports Med Phys Fitness 2020; 60:1057-1064. [PMID: 32955831 DOI: 10.23736/s0022-4707.20.10542-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Rock climbers are characterized by enhanced forearm fatigue resistance. This study compared the forearm isometric force of rock climbers (RC), strength-matched power lifters (PL) and aerobically trained (AT) athletes to determine the contribution of muscle oxygen desaturation during ischemia. METHODS Aerobically trained athletes (N.=6, 23±1 years, 77±1 kg), power lifters (N.=7, 24±1 years, 80±3 kg) and rock climbers (N.=8, 25±2 years, 74±2 kg) took part in a controlled forearm ischemic occlusion (5 min) assessment using near infrared spectroscopy. In addition, three fatigue protocols were completed: protocol 1, sustained maximal voluntary contraction (MVC) until exhaustion; protocol 2, sustained 40% MVC for 3 mins duration; protocol 3, an intermittent 40% MVC (5-s contraction, 5-s recovery) for a duration of 3 mins. Forearm contractile fatigue was quantified as the reduction in MVC. RESULTS MVC was equivalent between groups (P>0.05). Sustained MVC force (time to decline 50% MVC) was longer in the RC versus AT (AT: 35±5, PL: 46±6, RC: 54±4 s, P<0.05) and both AT and PL for sustained 40% MVC (AT: 56±9, RT: 62±8, RC: 87±7 s, P<0.05). Reduction in MVC was less in RC post intermittent 40% contractions (P<0.05). Oxygen desaturation half-time was longer in the RC versus AT (AT: 65±9, RT: 86±7, RC: 99±7 s, P<0.05) and this was associated with time to 50% MVC (P<0.05, r<sup>2</sup>=0.53) and time to 40% MVC task failure (P<0.05, r<sup>2</sup>=0.32). CONCLUSIONS Rock climbers' enhanced isometric fatigue-resistance and ability to maintain MVC was associated with a lower oxygen consumption of the forearm flexors during the ischemic state. This suggests a training adaptation involving intracellular oxygen consumption.
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Affiliation(s)
- Jordan Nolan
- Center for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Peter L Mclennan
- Center for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Gregory E Peoples
- Center for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia -
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17
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Kristensen AM, MacDougall KB, MacIntosh BR, Overgaard K. Is curvature of the force-velocity relationship affected by oxygen availability? Evidence from studies in ex vivo and in situ rat muscles. Pflugers Arch 2020; 472:597-608. [PMID: 32415461 DOI: 10.1007/s00424-020-02390-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/27/2020] [Accepted: 04/30/2020] [Indexed: 11/30/2022]
Abstract
The power of shortening contractions in skeletal muscle is determined by the force-velocity relationship. Fatigue has been reported to either increase or decrease the force-velocity curvature depending on experimental circumstances. These discrepant findings may be related to experimental differences in oxygen availability. We therefore investigated how the curvature of the force-velocity relationship in soleus and gastrocnemius rat muscles is affected during fatigue, in both an ex vivo setup without an intact blood perfusion and in an in situ setup with an intact blood perfusion. Furthermore, we investigated the effect of reduced oxygen concentrations and reduced diffusion distance on the curvature of the force-velocity relationship in ex vivo muscles, where muscle oxygen uptake relies on diffusion from the incubation medium. Muscles were electrically stimulated to perform repeated shortening contractions and force-velocity curves were determined in rested and fatigued conditions. The curvature increased during fatigue in the soleus muscles (both in situ and ex vivo), and decreased for the gastrocnemius muscles (in situ) or remained unchanged (ex vivo). Furthermore, under ex vivo conditions, neither reduced oxygen concentrations nor reduced diffusion distance conferred any substantial effect on the force-velocity curvature. In contrast, reduced oxygen availability and increased diffusion distance did increase the loss of maximal power during fatigue, mainly due to additional decreases in isometric force. We conclude that oxygen availability does not influence the fatigue-induced changes in force-velocity curvature. Rather, the observed variable fatigue profiles with regard to changes in curvature seem to be linked to the muscle fiber-type composition.
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Affiliation(s)
| | - K B MacDougall
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - B R MacIntosh
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - K Overgaard
- Department of Public Health, Aarhus University, Dalgas Avenue 4, Aarhus C, 8000, Aarhus, Denmark
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18
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Froyd C, Beltrami FG, Millet GY, MacIntosh BR, Noakes TD. Greater Short-Time Recovery of Peripheral Fatigue After Short- Compared With Long-Duration Time Trial. Front Physiol 2020; 11:399. [PMID: 32477158 PMCID: PMC7240104 DOI: 10.3389/fphys.2020.00399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/02/2020] [Indexed: 01/24/2023] Open
Abstract
The kinetics of recovery from neuromuscular fatigue resulting from exercise time trials (TTs) of different durations are not well-known. The aim of this study was to determine if TTs of three different durations would result in different short-term recovery in maximal voluntary contraction (MVC) and evoked peak forces. Twelve trained subjects performed repetitive concentric right knee extensions on an isokinetic dynamometer self-paced to last 3, 10, and 40 min (TTs). Neuromuscular function was assessed immediately (<2 s) and 1, 2, 4, and 8 min after completion of each TT using MVCs and electrical stimulation. Electrical stimulations consisted of single stimulus (SS), paired stimuli at 10 Hz (PS10), and paired stimuli at 100 Hz (PS100). Electrically evoked forces including the ratio of low- to high-frequency doublets were similar between trials at exercise cessation but subsequently increased more (P < 0.05) after the 3 min TT compared with either the 10 or 40 min TT when measured at 1 or 2 min of recovery. MVC force was not different between trials. The results demonstrate that recovery of peripheral fatigue including low-frequency fatigue depends on the duration and intensity of the preceding self-paced exercise. These differences in recovery probably indicate differences in the mechanisms of fatigue for these different TTs. Because recovery is faster after a 3 min TT than a 40 min TT, delayed assessment of fatigue will detect a difference in peripheral fatigue between trials that was not present at exercise cessation.
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Affiliation(s)
- Christian Froyd
- Faculty of Education, Arts and Sport, Western Norway University of Applied Sciences, Bergen, Norway.,Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Fernando G Beltrami
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, Switzerland
| | - Guillaume Y Millet
- Laboratoire Interuniversitaire de Biologie de la Motricité, University of Lyon, UJM Saint-Etienne, Saint Etienne, France
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Timothy D Noakes
- Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
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19
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Rockenfeller R, Günther M, Stutzig N, Haeufle DFB, Siebert T, Schmitt S, Leichsenring K, Böl M, Götz T. Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model. Front Physiol 2020; 11:306. [PMID: 32431619 PMCID: PMC7214688 DOI: 10.3389/fphys.2020.00306] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/19/2020] [Indexed: 12/01/2022] Open
Abstract
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Affiliation(s)
| | - Michael Günther
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
- Friedrich-Schiller-University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel F. B. Haeufle
- Hertie-Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls-University, Tübingen, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Syn Schmitt
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
| | - Kay Leichsenring
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Thomas Götz
- Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany
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20
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Mohamed AA. Can Proprioceptive Training Enhance Fatigability and Decrease Progression Rate of Sarcopenia in Seniors? A Novel Approach. Curr Rheumatol Rev 2020; 17:58-67. [PMID: 32348231 DOI: 10.2174/1573397116666200429113226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 04/08/2020] [Accepted: 04/13/2020] [Indexed: 01/03/2023]
Abstract
Sarcopenia is a common condition in older adults, which causes the frequent occurrence of muscle fatigue. Muscle fatigue commonly develops among seniors. Muscle fatigue is a type of physical fatigue that occurs due to either motor or sensory dysfunctions. Current interventions developed to decrease the occurrence of muscle fatigue, which include either increasing rest periods or subdividing large tasks into small ones. The effectiveness of these interventions is highly contradicted. Recently, researchers discovered that mechanoreceptors are the main receptors of muscle fatigue, however, no clinical study investigated the effect of performing proprioceptive training to enhance the mechanoreceptors and decrease the occurrence of muscle fatigue. Performing proprioceptive training could improve muscle fatigue by improving its sensory part. The function of mechanoreceptors might consequently enhance fatigue and decrease the progression rate of sarcopenia. Thus, this review was conducted to suggest a novel approach of treatment to enhance fatigue and decrease Sarcopenia in seniors. This might be accomplished through increasing the firing rate of α- motor neurons, increasing the amount of Ca2+ ions in the neuromuscular junction, slowing the progression rate of Sarcopenia, and correcting movement deviations, which commonly occur with muscle fatigue in seniors. In conclusion, proprioceptive training could play an effective role in decreasing the progression rate of sarcopenia and enhancing the fatigability among seniors.
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Affiliation(s)
- Ayman A Mohamed
- Department of Physiotherapy and Rehabilitation, School of Health Sciences, Istanbul Gelisim University, Istanbul, Turkey
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Akagi R, Hinks A, Davidson B, Power GA. Differential contributions of fatigue-induced strength loss and slowing of angular velocity to power loss following repeated maximal shortening contractions. Physiol Rep 2020; 8:e14362. [PMID: 32034892 PMCID: PMC7007446 DOI: 10.14814/phy2.14362] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 11/24/2022] Open
Abstract
The purpose of this study was to investigate the relationship between fatigue-induced reductions in isometric torque and isotonic power and to quantify the extent to which the decreases in angular velocity and dynamic torque can explain the power loss immediately following an isotonic fatiguing task and throughout recovery in seven young males and six young females. All measurements were performed with both legs. For dorsiflexion, fatigue-related time-course changes in isometric maximal voluntary contraction (MVC) torque, angular velocity, dynamic torque, and power production following repeated maximal isotonic contractions (load: 20% MVC) were investigated before, immediately after, and 1, 2, 5 and 10 min after a fatiguing task. There were no relationships between the fatigue-related reductions in isometric MVC torque and peak power at any timepoint, suggesting that fatigue-induced reductions in isometric MVC torque does not entirely reflect fatigue-induced changes in dynamic performance. The relative contribution of fatigue-related reduction in dynamic torque on power loss was greater immediately following the task, and lower throughout recovery than the corresponding decrease in angular velocity. Thus, power loss immediately following the task was more strongly related to the decline in dynamic torque; however, this relationship shifted throughout recovery to a greater dependence on slowing of angular velocity for power loss.
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Affiliation(s)
- Ryota Akagi
- College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, Japan.,Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, Canada
| | - Avery Hinks
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, Canada
| | - Brooke Davidson
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, Canada
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22
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Biesiadecki BJ, Brotto MA, Brotto LS, Koch LG, Britton SL, Nosek TM, Jin JP. Rats genetically selected for low and high aerobic capacity exhibit altered soleus muscle myofilament functions. Am J Physiol Cell Physiol 2020; 318:C422-C429. [PMID: 31875694 DOI: 10.1152/ajpcell.00430.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aerobic exercise capacity is critical to bodily health. As a model to investigate the mechanisms that determine health and disease, we employed low (LCR) and high (HCR) capacity running rat models selectively bred to concentrate the genes responsible for divergent aerobic running capacity. To investigate the skeletal muscle contribution to this innate difference in running capacity we employed an approach combining examination of the myofilament protein composition and contractile properties of the fast fiber extensor digitorum longus (EDL) and slow fiber soleus (SOL) muscles from LCR and HCR rats. Intact muscle force experiments demonstrate that SOL, but not EDL, muscles from LCR rats exhibit a three times greater decrease in fatigued force. To investigate the mechanism of this increased fatigability in the LCR SOL muscle, we determined the myofilament protein composition and functional properties. Force-Ca2+ measurements demonstrate decreased Ca2+ sensitivity of single skinned SOL muscle fibers from LCR compared with that of HCR rats. Segregating SOL fibers into fast and slow types demonstrates that the decreased Ca2+ sensitivity in LCR SOL results from a specific decrease in slow-type SOL fiber Ca2+ sensitivity such that it was similar to that of fast-type fibers. These results identify that the altered myofilament contractile properties of LCR SOL slow-type fibers result in a fast muscle type Ca2+ sensitivity and the LCR muscle phenotype. Overall our findings demonstrate alterations of the myofilament proteins could contribute to fatigability of the SOL muscle and the decreased innate aerobic running performance of LCR compared with HCR rats.
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Affiliation(s)
- B J Biesiadecki
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - M A Brotto
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Bone-Muscle Research Center, University of Texas, Arlington, Texas
| | - L S Brotto
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Bone-Muscle Research Center, University of Texas, Arlington, Texas
| | - L G Koch
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - S L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan.,Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - T M Nosek
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - J-P Jin
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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23
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Cornelius BW, Dib SO, Dowdy RA, Horton CK, Frimenko K, Mansour S, Sharkh FA, Joy MT, Hall DL, Emam HA, Jatana CA, Kennedy KS. Malignant Hyperthermia: A Case Study in the Dental Ambulatory Surgery Setting. Anesth Prog 2019; 66:202-210. [PMID: 31891296 DOI: 10.2344/anpr-66-04-03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Historically, patients who developed malignant hyperthermia had an extremely high rate of mortality. Today, if treated appropriately, patients who experience an episode of malignant hyperthermia will most likely survive. This dramatic decrease in mortality associated with malignant hyperthermia is due to several factors, including an increased understanding of the disease, improved diagnostic and monitoring equipment, and the development of lifesaving pharmacologic agents. This article presents the very likely case of acute malignant hyperthermia in a 24-year-old man with special needs, who presented for restorative dentistry under general anesthesia in the outpatient clinic of The Ohio State University's College of Dentistry.
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Affiliation(s)
- Bryant W. Cornelius
- Assistant Professor and Program Director of Dental/Oral Maxillofacial Anesthesiology, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Shelby Olsen Dib
- Resident, Dental/Oral Maxillofacial Anesthesiology, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Regina A. Dowdy
- Resident, Dental/Oral Maxillofacial Anesthesiology, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Christina K. Horton
- Chief Resident, General Practice Residency Program, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Katherine Frimenko
- Chief Resident, General Practice Residency Program, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Shadee Mansour
- Resident, General Practice Residency Program, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Farah Abu Sharkh
- Resident, General Practice Residency Program, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Marcus T. Joy
- Resident, Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry, Columbus, Ohio
| | - David L. Hall
- Associate Professor, General Practice Residency Program, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Hany A. Emam
- Assistant Professor, Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Courtney A. Jatana
- Assistant Professor, Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Kelly S. Kennedy
- Associate Professor and Program Director of Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry, Columbus, Ohio
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24
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Mohamed AA. Can Proprioceptive Training Reduce Muscle Fatigue in Patients With Motor Neuron Diseases? A New Direction of Treatment. Front Physiol 2019; 10:1243. [PMID: 31632290 PMCID: PMC6779805 DOI: 10.3389/fphys.2019.01243] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 09/10/2019] [Indexed: 12/11/2022] Open
Abstract
Muscle fatigue is a serious problem in patients with motor neuron diseases (MNDs). It commonly disturbs both daily life activity and rehabilitation tolerance. A particular concern should be taken when MNDs occur in older ages. Older patients with MNDs usually have a worse clinical presentation and a lower survival rate. This could increase the occurrence of muscle fatigue. Muscle fatigue occurs due to a dysfunction in either motor or sensory systems. Current exercise interventions performed to decrease the occurrence of muscle fatigue focused only on treating motor causes of muscle fatigue. It has been demonstrated that these interventions have a high debate in their effectiveness on decreasing the occurrence of muscle fatigue. Also, these exercise interventions ignored training the affected sensory part of muscle fatigue, however, the important role of the sensory system in driving the motor system. Thus, this review aimed to develop a novel exercise intervention by using proprioceptive training as an intervention to decrease the occurrence of muscle fatigue in patients with MNDs particularly, older ones. The physiological effects of proprioceptive training to decrease the occurrence of muscle fatigue could include two effects. The first effect includes the ability of the proprioceptive training to increase the sensitivity of muscle spindles as an attempt to normalize the firing rate of α-motoneurons, which their abnormalities have major roles in the occurrence of muscle fatigue. The second effect includes its ability to correct the abnormal movement-compensations, which develop due to the biomechanical constraints imposed on patients with MNDs.
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Affiliation(s)
- Ayman A. Mohamed
- Department of Physiotherapy and Rehabilitation, School of Health Sciences, Istanbul Gelisim University, Istanbul, Turkey
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25
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Straight CR, Bell KM, Slosberg JN, Miller MS, Swank DM. A myosin-based mechanism for stretch activation and its possible role revealed by varying phosphate concentration in fast and slow mouse skeletal muscle fibers. Am J Physiol Cell Physiol 2019; 317:C1143-C1152. [PMID: 31532715 DOI: 10.1152/ajpcell.00206.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stretch activation (SA) is a delayed increase in force following a rapid muscle length increase. SA is best known for its role in asynchronous insect flight muscle, where it has replaced calcium's typical role of modulating muscle force levels during a contraction cycle. SA also occurs in mammalian skeletal muscle but has previously been thought to be too low in magnitude, relative to calcium-activated (CA) force, to be a significant contributor to force generation during locomotion. To test this supposition, we compared SA and CA force at different Pi concentrations (0-16 mM) in skinned mouse soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscle fibers. CA isometric force decreased similarly in both muscles with increasing Pi, as expected. SA force decreased with Pi in EDL (40%), leaving the SA to CA force ratio relatively constant across Pi concentrations (17-25%). In contrast, SA force increased in soleus (42%), causing a quadrupling of the SA to CA force ratio, from 11% at 0 mM Pi to 43% at 16 mM Pi, showing that SA is a significant force modulator in slow-twitch mammalian fibers. This modulation would be most prominent during prolonged muscle use, which increases Pi concentration and impairs calcium cycling. Based upon our previous Drosophila myosin isoform studies and this work, we propose that in slow-twitch fibers a rapid stretch in the presence of Pi reverses myosin's power stroke, enabling quick rebinding to actin and enhanced force production, while in fast-twitch fibers, stretch and Pi cause myosin to detach from actin.
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Affiliation(s)
- Chad R Straight
- Department of Kinesiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts
| | - Kaylyn M Bell
- Department of Biological Sciences, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
| | - Jared N Slosberg
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York
| | - Mark S Miller
- Department of Kinesiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts
| | - Douglas M Swank
- Department of Biological Sciences, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York.,Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York
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26
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Cunha VCR, Aoki MS, Zourdos MC, Gomes RV, Barbosa WP, Massa M, Moreira A, Capitani CD. Sodium citrate supplementation enhances tennis skill performance: a crossover, placebo-controlled, double blind study. J Int Soc Sports Nutr 2019; 16:32. [PMID: 31370896 PMCID: PMC6676531 DOI: 10.1186/s12970-019-0297-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 07/08/2019] [Indexed: 11/25/2022] Open
Abstract
Background The efficacy of sodium citrate supplementation (SC) in exercise performance is unclear. Therefore, the aim of this study was to investigate the effect of SC on skilled tennis performance. Methods Ten Brazilian nationally-ranked young male tennis players (age: 17 ± 1 yrs.; stature: 176.7 ± 5.2 cm; body mass: 68.4 ± 7.9 kg) participated in this crossover, placebo-controlled, double-blind study. Upon arrival, at baseline, in both experimental sessions blood was collected, then subjects ingested either sodium citrate (SC - 0.5 g.kg−1BM in capsules of 500 mg) or a placebo (PLA). Two hours later, pre-match blood was collected then skills tests (skill tennis performance test - STPT, repeated-sprint ability shuttle test - RSA) were performed followed by a 1-h simulated match. Immediately following the match, blood was again collected, and STPT, and RSA were administered. Results All metabolic parameters (i.e. base excess, pH, bicarbonate, and blood lactate) increased (p < 0.001) from baseline to pre-match and post-match in SC condition. Each metabolic parameter was greater (p < 0.001) in SC compared to PLA condition at both pre- and post-match. The SC condition elicited a greater (p < 0.01) shot consistency at post-match in the STPT vs. PLA condition (SC: 58.5 ± 14.8% vs. PLA: 40.4 ± 10.4%). A greater (p < 0.001) amount of games won was observed in the simulated match for SC condition vs. PLA condition (SC: 8.0 ± 1.6 vs. PLA: 6.0 ± 1.7). Additionally, the games won during the simulated match in SC condition was positively correlated with percentage shot consistency (r = 0.67, p < 0.001). Conclusions The current findings suggest that SC supplementation is an effective ergogenic aid to enhance skilled tennis performance.
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Affiliation(s)
- Vivian C R Cunha
- School of Applied Sciences, University of Campinas, Rua Pedro Zaccaria 1300, Limeira, 13484-350, Sao Paulo, Brazil
| | - Marcelo S Aoki
- School of Arts, Sciences and Humanities, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Michael C Zourdos
- Department of Exercise Science and Health Promotion, Muscle Physiology Laboratory, Florida Atlantic University, Kissimme, Florida, USA
| | - Rodrigo V Gomes
- School of Arts, Sciences and Humanities, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Wesley P Barbosa
- School of Arts, Sciences and Humanities, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Marcelo Massa
- School of Arts, Sciences and Humanities, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Alexandre Moreira
- School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Caroline D Capitani
- School of Applied Sciences, University of Campinas, Rua Pedro Zaccaria 1300, Limeira, 13484-350, Sao Paulo, Brazil.
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27
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Hallal N, El Khayat El Sabbouri H, Salami A, Ramadan W, Khachfe H, Moustafa ME, Khalil M, Joumaa WH. Impacts of prolonged chlorpyrifos exposure on locomotion and slow-and fast- twitch skeletal muscles contractility in rats. Toxicol Rep 2019; 6:598-606. [PMID: 31297333 PMCID: PMC6597941 DOI: 10.1016/j.toxrep.2019.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 06/08/2019] [Accepted: 06/11/2019] [Indexed: 12/11/2022] Open
Abstract
AIM Investigate the effect of dietary exposure to chlorpyrifos on locomotion and contraction of soleus andextensor digitorum longus (edl) involved in locomotion. Methods: Rats were fed diets containing 1 or 5 mg kg-1 of chlorpyrifos for six weeks. Locomotion has been assessed weekly using beam walking and beam balance tests. Soleus and edl were removed to study contractile properties, myofibrillar protein content and myosin heavy chain isoforms. RESULTS Animals treated with 5 mg kg-1 chlorpyrifos had a decrease body weight. An increase by 28% and 24% in latency time assessed by beam walking test and a decrease by 9% and 13% in the beam balance time was reported after 6 weeks of 1 and 5 chlorpyrifos exposure respectively. The contractile properties in soleus showed an increase in twitch amplitude by 25% and 63% in 1 and 5 doses respectively, without modification in the contraction time and half relaxation time. edl treated with 1 mg kg-1 showed a decrease by 35%, 42% and 22% in twitch amplitude, contraction time and half relaxation time respectively. edl treated with 5 mg kg-1 showed an increase of 23% in twitch amplitude without modification of the other parameters. These changes were associated with modification of myofibrillar protein content in all treated groups. Myosin heavy chain isoforms were altered in both skeletal muscles treated with 1 mg kg-1. CONCLUSION Exposure to chlorpyrifos can alter the locomotion and produce physiological changes in a dose and muscle type related manner.
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Affiliation(s)
- Nancy Hallal
- Department of Biological Sciences, Faculty of Science, Beirut Arab University, Lebanon
| | - Hiba El Khayat El Sabbouri
- Laboratoire Rammal Hassan Rammal, Equipe de recherche PhyToxE, Faculté des Sciences (section V), Université libanaise, Nabatieh, Lebanon
- PERITOX UMR-I-0, University of Picardie Jules Verne, 80025, Amiens, France
| | - Ali Salami
- Laboratoire Rammal Hassan Rammal, Equipe de recherche PhyToxE, Faculté des Sciences (section V), Université libanaise, Nabatieh, Lebanon
| | - Wiam Ramadan
- Laboratoire Rammal Hassan Rammal, Equipe de recherche PhyToxE, Faculté des Sciences (section V), Université libanaise, Nabatieh, Lebanon
- Lebanese Institute for Biomedical Research and Application (LIBRA), International University of Beirut (BIU), Beirut, Lebanon
| | - Hassan Khachfe
- Lebanese Institute for Biomedical Research and Application (LIBRA), International University of Beirut (BIU), Beirut, Lebanon
| | - Mohamed E. Moustafa
- Department of Biological Sciences, Faculty of Science, Beirut Arab University, Lebanon
- Department of Biochemistry, Faculty of Sciences, Alexandria University, Egypt
| | - Mahmoud Khalil
- Department of Biological Sciences, Faculty of Science, Beirut Arab University, Lebanon
| | - Wissam H. Joumaa
- Laboratoire Rammal Hassan Rammal, Equipe de recherche PhyToxE, Faculté des Sciences (section V), Université libanaise, Nabatieh, Lebanon
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28
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Krüger RL, Aboodarda SJ, Jaimes LM, MacIntosh BR, Samozino P, Millet GY. Fatigue and recovery measured with dynamic properties versus isometric force: effects of exercise intensity. ACTA ACUST UNITED AC 2019; 222:jeb.197483. [PMID: 30890621 DOI: 10.1242/jeb.197483] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/13/2019] [Indexed: 11/20/2022]
Abstract
Although fatigue can be defined as an exercise-related decrease in maximal power or isometric force, most studies have assessed only isometric force. The main purpose of this experiment was to compare dynamic measures of fatigue [maximal torque (T max), maximal velocity (V max) and maximal power (P max)] with measures associated with maximal isometric force [isometric maximal voluntary contraction (IMVC) and maximal rate of force development (MRFD)] 10 s after different fatiguing exercises and during the recovery period (1-8 min after). Ten young men completed six experimental sessions (3 fatiguing exercises×2 types of fatigue measurements). The fatiguing exercises were: 30 s all-out intensity (AI), 10 min at severe intensity (SI) and 90 min at moderate intensity (MI). Relative P max decreased more than IMVC after AI exercise (P=0.005) while the opposite was found after SI (P=0.005) and MI tasks (P<0.001). There was no difference between the decrease in IMVC and T max after the AI exercise, but IMVC decreased more than T max immediately following and during the recovery from the SI (P=0.042) and MI exercises (P<0.001). Depression of MRFD was greater than V max after all fatiguing exercises and during recovery (all P<0.05). Despite the general definition of fatigue, isometric assessment of fatigue is not interchangeable with dynamic assessment following dynamic exercises with large muscle mass of different intensities, i.e. the results from isometric function cannot be used to estimate dynamic function and vice versa. This implies different physiological mechanisms for the various measures of fatigue.
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Affiliation(s)
- Renata L Krüger
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Saied Jalal Aboodarda
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Libia Marcela Jaimes
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Pierre Samozino
- Univ Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, F-73000 Chambéry, France
| | - Guillaume Y Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
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Górecki DC. P2X7 purinoceptor as a therapeutic target in muscular dystrophies. Curr Opin Pharmacol 2019; 47:40-45. [PMID: 30901735 DOI: 10.1016/j.coph.2019.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/05/2019] [Accepted: 02/15/2019] [Indexed: 01/07/2023]
Abstract
Mutations in the dystrophin and sarcoglycans genes result in muscular dystrophies causing severe disability and premature death and where no effective treatment is available. New therapeutic approaches targeting secondary disease mechanisms have a strong translational potential. Dystrophic muscle damage triggers release of ATP whilst loss of ecto-ATPase activity of sarcoglycan further elevates extracellular ATP (eATP) levels. Such a high eATP activates P2X7 purinoceptors on immune cells; these contribute to chronic inflammatory and immune responses that exacerbate the dystrophic pathology. Dystrophin mutations coincide with a significant P2X7 upregulation in Duchenne muscular dystrophy (DMD) muscle and alter receptor signalling in mouse dystrophic myoblasts and myofibers. P2X7 overexpression combined with the eATP-rich environment lead to cell dysfunction and death and ultimately to ineffective regeneration. P2X7 is therefore a therapeutic target for reducing damaging inflammation and supporting the repair of dystrophic muscles. Accordingly, genetic ablation and pharmacological inhibition of the eATP-P2X7 axis alleviated dystrophic phenotypes in mouse models of dystrophinopathy and sarcoglycanopathy. Thus, P2X7 inhibitors are good candidates for rapid re-purposing for the treatment of these highly debilitating diseases. Such a therapy is not constrained by causative mutations, so it would be suitable for all patients. Moreover, it appears effective in alleviating both muscle and non-muscle symptoms.
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Affiliation(s)
- Dariusz C Górecki
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, UK; Military Institute of Hygiene and Epidemiology, Warsaw, Poland.
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30
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Associations between clinical symptoms, plasma norepinephrine and deregulated immune gene networks in subgroups of adolescent with Chronic Fatigue Syndrome. Brain Behav Immun 2019; 76:82-96. [PMID: 30419269 DOI: 10.1016/j.bbi.2018.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/01/2018] [Accepted: 11/08/2018] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Chronic Fatigue Syndrome (CFS) is one of the most important causes of disability among adolescents while limited knowledge exists on genetic determinants underlying disease pathophysiology. METHODS We analyzed deregulated immune-gene modules using Pathifier software on whole blood gene expression data (29 CFS patients, 18 controls). Deconvolution of immune cell subtypes based on gene expression profile was performed using CIBERSORT. Supervised consensus clustering on pathway deregulation score (PDS) was used to define CFS subgroups. Associations between PDS and immune, neuroendocrine/autonomic and clinical markers were examined. The impact of plasma norepinephrine level on clinical markers over time was assessed in a larger cohort (91 patients). RESULTS A group of 29 immune-gene sets was shown to differ patients from controls and detect subgroups within CFS. Group 1P (high PDS, low norepinephrine, low naïve CD4+ composition) had strong association with levels of serum C-reactive protein and Transforming Growth Factor-beta. Group 2P (low PDS, high norepinephrine, high naïve CD4+ composition) had strong associations with neuroendocrine/autonomic markers. The corresponding plasma norepinephrine level delineated 91 patients into two subgroups with significant differences in fatigue score. CONCLUSION We identified 29 immune-gene sets linked to plasma norepinephrine level that could delineate CFS subgroups. Plasma norepinephrine stratification revealed that lower levels of norepinephrine were associated with higher fatigue. Our data suggests potential involvement of neuro-immune dysregulation and genetic stratification in CFS.
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31
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Sidorenko S, Klimanova E, Milovanova K, Lopina OD, Kapilevich LV, Chibalin AV, Orlov SN. Transcriptomic changes in C2C12 myotubes triggered by electrical stimulation: Role of Ca2+i-mediated and Ca2+i-independent signaling and elevated [Na+]i/[K+]i ratio. Cell Calcium 2018; 76:72-86. [DOI: 10.1016/j.ceca.2018.09.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/18/2018] [Accepted: 09/26/2018] [Indexed: 12/25/2022]
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32
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Majumder A, Singh M, George AK, Tyagi SC. Restoration of skeletal muscle homeostasis by hydrogen sulfide during hyperhomocysteinemia-mediated oxidative/ER stress condition 1. Can J Physiol Pharmacol 2018; 97:441-456. [PMID: 30422673 DOI: 10.1139/cjpp-2018-0501] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Elevated homocysteine (Hcy), i.e., hyperhomocysteinemia (HHcy), causes skeletal muscle myopathy. Among many cellular and metabolic alterations caused by HHcy, oxidative and endoplasmic reticulum (ER) stress are considered the major ones; however, the precise molecular mechanism(s) in this process is unclear. Nevertheless, there is no treatment option available to treat HHcy-mediated muscle injury. Hydrogen sulfide (H2S) is increasingly recognized as a potent anti-oxidant, anti-apoptotic/necrotic/pyroptotic, and anti-inflammatory compound and also has been shown to improve angiogenesis during ischemic injury. Patients with CBS mutation produce less H2S, making them vulnerable to Hcy-mediated cellular damage. Many studies have reported bidirectional regulation of ER stress in apoptosis through JNK activation and concomitant attenuation of cell proliferation and protein synthesis via PI3K/AKT axis. Whether H2S mitigates these detrimental effects of HHcy on muscle remains unexplored. In this review, we discuss molecular mechanisms of HHcy-mediated oxidative/ER stress responses, apoptosis, angiogenesis, and atrophic changes in skeletal muscle and how H2S can restore skeletal muscle homeostasis during HHcy condition. This review also highlights the molecular mechanisms on how H2S could be developed as a clinically relevant therapeutic option for chronic conditions that are aggravated by HHcy.
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Affiliation(s)
- Avisek Majumder
- a Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.,b Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Mahavir Singh
- a Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.,c Eye and Vision Science Laboratory, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Akash K George
- a Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.,c Eye and Vision Science Laboratory, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Suresh C Tyagi
- a Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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Wilson DF, Matschinsky FM. Metabolic homeostasis: oxidative phosphorylation and the metabolic requirements of higher plants and animals. J Appl Physiol (1985) 2018; 125:1183-1192. [DOI: 10.1152/japplphysiol.00352.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A model of oxidative phosphorylation and its regulation is presented, which is consistent with the experimental data on metabolism in higher plants and animals. The variables that provide real-time control of metabolic status are: intramitochondrial [NAD+]/[NADH], energy state ([ATP]/[ADP][Pi]), and local oxygen concentration ([O2]). ATP consumption and respiratory chain enzyme content are tissue specific (liver vs. heart muscle), and the latter is modulated by chronic alterations in ATP consumption (i.e., endurance training etc.). ATP consumption affects the energy state, which increases or decreases as necessary to match synthesis with consumption. [NAD+]/[NADH], local [O2], and respiratory chain content determine the energy state at which match of synthesis and utilization is achieved. Tissues vary widely in their ranges of ATP consumption. Expressed as the turnover of cytochrome c, the rates may change little (7 to 12/s) (liver) or a lot (1 to >300/s) (flight muscle of birds, bats, and insects). Ancillary metabolic pathways, including creatine or arginine kinase, glycerol phosphate shuttle, fatty acid, and citric acid cycle dehydrogenases, are responsible for meeting tissue-specific differences in maximal rate and range in ATP utilization without displacing metabolic homeostasis. Intramitochondrial [NAD+]/[NADH], [ATP], and [Pi] are adjusted to keep [ADP] and [AMP] similar for all tissues despite large differences in ranges in ATP utilization. This is essential because [ADP] and [AMP], particularly the latter, have major roles in regulating the activity of many enzymes and signaling pathways (AMP deaminase, AMP dependent protein kinases, etc.) common to all higher plants and animals. NEW & NOTEWORTHY Oxidative phosphorylation has an intrinsic program that sets and stabilizes cellular energy state ([ATP]/[ADP][Pi]), and thereby metabolic homeostasis. A computational model consistent with regulation of oxidative phosphorylation in higher plants and animals is presented. Focus is on metabolism ancillary to oxidative phosphorylation by which it was integrated into preexisting metabolic regulation and adapted by evolution to develop cells and tissues with differing rates of ATP utilization: i.e., liver versus brain versus muscle.
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Affiliation(s)
- David F. Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Franz M. Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Devrome AN, MacIntosh BR. Force-velocity relationship during isometric and isotonic fatiguing contractions. J Appl Physiol (1985) 2018; 125:706-714. [PMID: 29856265 DOI: 10.1152/japplphysiol.01119.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fatiguing contractions change the force-velocity relationship, but assessment of this relationship in fatigue has usually been obtained after isometric contractions. We studied fatigue caused by isometric or isotonic contractions, by assessment of the force-velocity relationship while the contractions maintaining fatigue were continued. This approach allowed determination of the force-velocity relationship during a steady condition of fatigue. We used the in situ rat medial gastrocnemius muscle, a physiologically relevant preparation. Intermittent (1/s) stimulation at 170 Hz for 100 ms resulted in decreased isometric force to ~35% of initial or decreased peak velocity of shortening in dynamic contractions to ~45% of initial. Dynamic contractions resulted in a transient initial increase in velocity, followed by a rapid decline until a reasonably steady level was maintained. Data were fit to the classic Hill equation for determination of the force-velocity relationship. Isometric and dynamic contractions resulted in similar decreases in maximal isometric force and peak power. Only Vmax was different between the types of contraction ( P < 0.005) with greater decrease in Vmax during isotonic contractions to 171.7 ± 7.3 mm/s than during isometric contractions to 208.8 mm/s. Curvature indicated by a/Po (constants from fit to Hill equation) changed from 0.45 ± 0.04 to 0.71 ± 0.11 during isometric contractions and from 0.51 ± 0.04 to 0.85 ± 0.18 during isotonic contractions. Recovery was incomplete 45 min after stopping the intermittent contractions. At this time, recovery of low-frequency isometric force was substantially less after isometric contractions, implicating force during intermittent contractions as a determining factor with this measure of fatigue. NEW & NOTEWORTHY The force-velocity relationship was captured while fatigue was maintained at a constant level during isometric and dynamic contractions. The curvature of the force-velocity relationship was less curved during fatigue than prefatigued, but within 45 min this recovered. Low-frequency fatigue persisted with greater depression of low-frequency force after isometric contractions, possibly because of higher force contractions during intermittent contractions.
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Affiliation(s)
- Andrea N Devrome
- Faculty of Kinesiology, University of Calgary , Calgary, AB , Canada
| | - Brian R MacIntosh
- Faculty of Kinesiology, University of Calgary , Calgary, AB , Canada
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35
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Than C, Seidl L, Tosovic D, Brown JM. Test-retest reliability of laser displacement mechanomyography in paraspinal muscles while in lumbar extension or flexion. J Electromyogr Kinesiol 2018; 41:60-65. [DOI: 10.1016/j.jelekin.2018.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 05/01/2018] [Accepted: 05/09/2018] [Indexed: 11/30/2022] Open
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Vellecco V, Armogida C, Bucci M. Hydrogen sulfide pathway and skeletal muscle: an introductory review. Br J Pharmacol 2018; 175:3090-3099. [PMID: 29767441 PMCID: PMC6031874 DOI: 10.1111/bph.14358] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/18/2018] [Accepted: 04/30/2018] [Indexed: 12/13/2022] Open
Abstract
The presence of the H2 S pathway in skeletal muscle (SKM) has recently been established. SKM expresses the three constitutive H2 S-generating enzymes in animals and humans, and it actively produces H2 S. The main, recognized molecular targets of H2 S, that is, potassium channels and PDEs, have been evaluated in SKM physiology in order to hypothesize a role for H2 S signalling. SKM dysfunctions, including muscular dystrophy and malignant hyperthermia, have also been evaluated as conditions in which the H2 S and transsulfuration pathways have been suggested to be involved. The intrinsic complexity of the molecular mechanisms involved in excitation-contraction (E-C) coupling together with the scarcity of preclinical models of SKM-related disorders have hampered any advances in the knowledge of SKM function. Here, we have addressed the role of the H2 S pathway in E-C coupling and the relative importance of cystathionine β-synthase, cistathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase in SKM diseases.
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Affiliation(s)
- Valentina Vellecco
- Department of Pharmacy, School of Medicine, University of Naples 'Federico II', Naples, 80131, Italy
| | - Chiara Armogida
- Department of Pharmacy, School of Medicine, University of Naples 'Federico II', Naples, 80131, Italy
| | - Mariarosaria Bucci
- Department of Pharmacy, School of Medicine, University of Naples 'Federico II', Naples, 80131, Italy
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Penasso H, Thaller S. Model-based analysis of fatigued human knee extensors : Effects of isometrically induced fatigue on Hill-type model parameters and ballistic contractions. Eur J Appl Physiol 2018; 118:1447-1461. [PMID: 29730804 PMCID: PMC6028922 DOI: 10.1007/s00421-018-3875-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/23/2018] [Indexed: 02/05/2023]
Abstract
This study investigated the effect of isometrically induced fatigue on Hill-type muscle model parameters and related task-dependent effects. Parameter identification methods were used to extract fatigue-related parameter trends from isometric and ballistic dynamic maximum voluntary knee extensions. Nine subjects, who completed ten fatiguing sets, each consisting of nine 3 s isometric maximum voluntary contractions with 3 s rest plus two ballistic contractions with different loads, were analyzed. Only at the isometric task, the identified optimized model parameter values of muscle activation rate and maximum force generating capacity of the contractile element decreased from [Formula: see text] to [Formula: see text] Hz and from [Formula: see text] to [Formula: see text] N, respectively. For all tasks, the maximum efficiency of the contractile element, mathematically related to the curvature of the force-velocity relation, increased from [Formula: see text] to [Formula: see text]. The model parameter maximum contraction velocity decreased from [Formula: see text] to [Formula: see text] m/s and the stiffness of the serial elastic element from [Formula: see text] to [Formula: see text] N/mm. Thus, models of fatigue should consider fatigue dependencies in active as well as in passive elements, and muscle activation dynamics should account for the task dependency of fatigue.
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Affiliation(s)
- Harald Penasso
- Institute of Sport Science, University of Graz, Mozartgasse 14, 8010, Graz, Austria.
| | - Sigrid Thaller
- Institute of Sport Science, University of Graz, Mozartgasse 14, 8010, Graz, Austria
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曾 林, 刘 静. [Mitochondrial calcium overload in the masseter muscle of rats with occlusal interference: ionic changes and regulation by calmodulin kinase II]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2018; 38:755-760. [PMID: 29997101 PMCID: PMC6765715 DOI: 10.3969/j.issn.1673-4254.2018.06.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Indexed: 06/08/2023]
Abstract
OBJECTIVE To investigate the changes in mitochondrial calcium and extracellular sodium concentrations in the masseter muscle of rats with occlusal interference and the regulatory mechanism of mitochondrial Ca2+ overload by calmodulin kinase II (CaMK II). METHODS SD rat models of occlusal interference were established by placing a stainless steel segments (0.8 mm in diameter) to raise the occlusal surface of the upper right first molar. At 3, 7, 14, and 21 days after occlusal interference and at 3 days after removal of occlusal interference, HE staining was used to observe the histomorphological changes of the masseter muscle. Mitochondrial calcium concentration in the masseter muscle was detected using fluorescence spectrophotometry, and direct turbidimetry with potassium pyroantimonate was used to detect the extracellular sodium concentration; the expression levels of masseter muscle p-CaMK II (Thr287) and CaMK II were detected using Western blotting. RESULTS Compared with those in the corresponding control groups, mitochondrial Ca2+ concentration in the masseter muscle on occlusal interference side increased significantly at 3, 7, 14 and 21 days after occlusal interference (P<0.05), but was significantly lowered at 3 days after removal of the interference (P<0.05). The concentration of extracellular Na+ increased progressively with time at 3, 7, 14 and 21 days after occlusal interference (P<0.05), and was significantly decreased at 3 days after interference removal (P<0.05). Occlusal interference for 3, 7 and 14 days resulted in significantly increased expressions of p-CaMK II (Thr287) and CaMK II (P<0.05), which was significantly decreased at 21 days compared with those in the control groups (P<0.05) and further decreased after removal of occlusal interference (P<0.05). Similar changes were also observed on the side without interference, but the changes on the interference side were more obvious (P<0.05). CONCLUSION Occlusal interference causes elevated mitochondrial Ca2+ and extracellular Na+ concentrations in the masseter muscle of rats to lead to calcium overload; the increase in mitochondrial Ca2+ concentration is correlated with the phosphorylation level of CaMK II signaling pathway, suggesting a negative feedback regulation mechanism by the CaMK II signal pathway.
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Affiliation(s)
- 林 曾
- 暨南大学 口腔医学院,广东 广州 510632College of Stomatology, Jinan University, Guangzhou 510632, China
- 华侨医院口腔科,广东 广州 510630Department of Stomatology, First Affiliated Hospital of Jinan University, Guangzhou 510630, China
| | - 静 刘
- 暨南大学 口腔医学院修复学教研室,广东 广州 510632Department of Prosthodontics, College of Stomatology, Jinan University, Guangzhou 510632, China
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Gittings W, Bunda J, Vandenboom R. Myosin phosphorylation potentiates steady-state work output without altering contractile economy of mouse fast skeletal muscles. ACTA ACUST UNITED AC 2018; 221:jeb.167742. [PMID: 29122950 DOI: 10.1242/jeb.167742] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/28/2017] [Indexed: 11/20/2022]
Abstract
Skeletal myosin light chain kinase (skMLCK)-catalyzed phosphorylation of the myosin regulatory light chain (RLC) increases (i.e. potentiates) mechanical work output of fast skeletal muscle. The influence of this event on contractile economy (i.e. energy cost/work performed) remains controversial, however. Our purpose was to quantify contractile economy of potentiated extensor digitorum longus (EDL) muscles from mouse skeletal muscles with (wild-type, WT) and without (skMLCK ablated, skMLCK-/-) the ability to phosphorylate the RLC. Contractile economy was calculated as the ratio of total work performed to high-energy phosphate consumption (HEPC) during a period of repeated isovelocity contractions that followed a potentiating stimulus (PS). Consistent with genotype, the PS increased RLC phosphorylation measured during, before and after isovelocity contractions in WT but not in skMLCK-/- muscles (i.e. 0.65 and 0.05 mol phosphate mol-1 RLC, respectively). In addition, although the PS enhanced work during repeated isovelocity contractions in both genotypes, the increase was significantly greater in WT than in skMLCK-/- muscles (1.51±0.03 versus 1.10±0.05, respectively; all data P<0.05, n=8). Interestingly, the HEPC determined during repeated isovelocity contractions was statistically similar between genotypes at 19.03±3.37 and 16.02±3.41 μmol P; respectively (P<0.27). As a result, despite performing significantly more work, the contractile economy calculated for WT muscles was similar to that calculated for skMLCK-/- muscles (i.e. 5.74±0.67 and 4.61±0.71 J kg-1 μmol-1 P, respectively (P<0.27). In conclusion, our results support the notion that myosin RLC phosphorylation enhances dynamic contractile function of mouse fast skeletal muscle but does so without decreasing contractile economy.
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Affiliation(s)
- William Gittings
- Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St Catharines, ON L2S 3A1, Canada
| | - Jordan Bunda
- Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St Catharines, ON L2S 3A1, Canada
| | - Rene Vandenboom
- Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St Catharines, ON L2S 3A1, Canada
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Goodall S, Howatson G, Thomas K. Modulation of specific inhibitory networks in fatigued locomotor muscles of healthy males. Exp Brain Res 2017; 236:463-473. [PMID: 29214392 PMCID: PMC5809538 DOI: 10.1007/s00221-017-5142-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/01/2017] [Indexed: 12/12/2022]
Abstract
Reduced maximal force capability of skeletal muscle, as a consequence of exercise, can be due to peripheral or central fatigue mechanisms. In upper-limb muscles, neuromuscular fatigue is concurrent with reduced corticospinal excitability and increased inhibition (lengthened corticospinal silent period [CSP]; reduced short-interval intracortical inhibition [SICI] ratio). However, it is unclear whether these adjustments occur in response to fatiguing exercise of locomotor muscles. This study examined the effect of fatiguing, maximal, knee-extensor exercise on motor cortical excitability and inhibition. Thirteen males performed three 30-s maximal, isometric contractions with the dominant knee-extensors (MVC1, MVC2 and MVC3), separated by 60 s. At the end of, and between each MVC, neuromuscular fatigue, corticospinal excitability, CSP and SICI were assessed with supramaximal stimulation of the femoral nerve, and motor cortical stimulation, respectively. Repeated MVCs caused progressive reductions in MVC (- 10, - 24 and - 29%, respectively, P ≤ 0.01), along with significant peripheral (reductions in potentiated twitch of - 23, -53 and - 60%, respectively, P < 0.001) and central (reductions in VA of - 10% and - 13% post-MVC2 and 3, respectively, P ≤ 0.01) fatigue. Following MVC1 corticospinal excitability was reduced, and remained depressed thereafter. CSP increased in duration and remained longer throughout the protocol; whereas, no change in SICI was observed. Repeated, sustained, maximal contractions of the knee-extensors elicited substantial peripheral and central fatigue that was accompanied by a concomitant reduction in corticospinal excitability. However, divergent responses exist between inhibitory networks within the motor cortex, the activity of inhibitory networks mediated by GABAB are increased, whereas those mediated by GABAA are not.
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Affiliation(s)
- Stuart Goodall
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.
| | - Glyn Howatson
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK
- Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa
| | - Kevin Thomas
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK
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Becker RA, Cluff K, Duraisamy N, Casale GP, Pipinos II. Analysis of ischemic muscle in patients with peripheral artery disease using X-ray spectroscopy. J Surg Res 2017; 220:79-87. [PMID: 29180215 PMCID: PMC5708859 DOI: 10.1016/j.jss.2017.06.073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/23/2017] [Accepted: 06/28/2017] [Indexed: 01/05/2023]
Abstract
BACKGROUND Peripheral artery disease (PAD) is a vascular disease caused by atherosclerosis, resulting in decreased blood flow to the lower extremities. The ankle-brachial index (ABI) is a standard PAD diagnostic test but only identifies reduced blood flow based on blood pressure differences. The early signs of PAD manifest themselves not only at a clinical level but also at an elemental and biochemical level. However, the biochemical and elemental alterations to PAD muscle are not well understood. The objective of this study was to compare fundamental changes in intracellular elemental compositions between control, claudicating, and critical limb ischemia muscle tissue. MATERIALS AND METHODS Gastrocnemius biopsies from three subjects including one control (ABI ≥ 0.9), one claudicating (0.4 ≤ ABI < 0.9), and one critical limb ischemia patient (ABI < 0.4) were evaluated using a scanning electron microscope and energy dispersive X-ray spectroscopy to quantify differences in elemental compositions. Spectra were collected for five myofibers per specimen. An analysis of variance was performed to identify significant differences in muscle elemental compositions. RESULTS This study revealed that intracellular magnesium and calcium were lower in PAD compared with control myofibers, whereas sulfur was higher. Magnesium and calcium are antagonistic, meaning, if magnesium concentrations go down calcium concentrations should go up. However, our findings do not support this antagonism in PAD. Our analysis found decreases in sodium and potassium, in PAD myofibers. CONCLUSIONS These findings may provide insight into the pathologic mechanisms that may operate in ischemic muscle and aid in the development of specialized preventive and rehabilitative treatment plans for PAD patients.
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Affiliation(s)
- Ryan A Becker
- Biomedical Engineering Department, Wichita State University, Wichita, Kansas
| | - Kim Cluff
- Biomedical Engineering Department, Wichita State University, Wichita, Kansas.
| | | | - George P Casale
- Division of General Surgery, Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska
| | - Iraklis I Pipinos
- Division of General Surgery, Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska; Department of VA Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, Nebraska
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Muscle fatigue: general understanding and treatment. Exp Mol Med 2017; 49:e384. [PMID: 28983090 PMCID: PMC5668469 DOI: 10.1038/emm.2017.194] [Citation(s) in RCA: 276] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 05/20/2017] [Accepted: 05/23/2017] [Indexed: 12/19/2022] Open
Abstract
Muscle fatigue is a common complaint in clinical practice. In humans, muscle fatigue can be defined as exercise-induced decrease in the ability to produce force. Here, to provide a general understanding and describe potential therapies for muscle fatigue, we summarize studies on muscle fatigue, including topics such as the sequence of events observed during force production, in vivo fatigue-site evaluation techniques, diagnostic markers and non-specific but effective treatments.
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Morales-Alamo D, Guerra B, Ponce-González JG, Guadalupe-Grau A, Santana A, Martin-Rincon M, Gelabert-Rebato M, Cadefau JA, Cusso R, Dorado C, Calbet JAL. Skeletal muscle signaling, metabolism, and performance during sprint exercise in severe acute hypoxia after the ingestion of antioxidants. J Appl Physiol (1985) 2017; 123:1235-1245. [PMID: 28819003 DOI: 10.1152/japplphysiol.00384.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/19/2017] [Accepted: 08/06/2017] [Indexed: 12/18/2022] Open
Abstract
The aim of this study was to determine if reactive oxygen species (ROS) could play a role in blunting Thr172-AMP-activated protein kinase (AMPK)-α phosphorylation in human skeletal muscle after sprint exercise in hypoxia and to elucidate the potential signaling mechanisms responsible for this response. Nine volunteers performed a single 30-s sprint (Wingate test) in two occasions while breathing hypoxic gas ([Formula: see text] = 75 mmHg): one after the ingestion of placebo and another following the intake of antioxidants (α-lipoic acid, vitamin C, and vitamin E), with a randomized double-blind design. Vastus lateralis muscle biopsies were obtained before, immediately after, and 30- and 120-min postsprint. Compared with the control condition, the ingestion of antioxidants resulted in lower plasma carbonylated proteins, attenuated elevation of the AMP-to-ATP molar ratio, and reduced glycolytic rate (P < 0.05) without significant effects on performance or V̇o2 The ingestion of antioxidants did not alter the basal muscle signaling. Thr172-AMPKα and Thr184/187-transforming growth factor-β-activated kinase 1 (TAK1) phosphorylation were not increased after the sprint regardless of the ingestion of antioxidants. Thr286-CaMKII phosphorylation was increased after the sprint, but this response was blunted by the antioxidants. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation increased immediately after the sprints coincident with increased Akt phosphorylation. In summary, antioxidants attenuate the glycolytic response to sprint exercise in severe acute hypoxia and modify the muscle signaling response to exercise. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation, a known mechanism of Thr172-AMPKα phosphorylation inhibition, is increased immediately after sprint exercise in hypoxia, probably by a mechanism independent of ROS.NEW & NOTEWORTHY The glycolytic rate is increased during sprint exercise in severe acute hypoxia. This study showed that the ingestion of antioxidants before sprint exercise in severe acute hypoxia reduced the glycolytic rate and attenuated the increases of the AMP-to-ATP and the reduction of the NAD+-to-NADH.H+ ratios. This resulted in a modified muscle signaling response with a blunted Thr286-CaMKII but similar AMP-activated protein kinase phosphorylation responses in the sprints preceded by the ingestion of antioxidants.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Borja Guerra
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | | | - Amelia Guadalupe-Grau
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,Genetic Unit, Chilhood Hospital-Materno Infantil de Las Palmas, Las Palmas de Gran Canaria, Spain; and
| | - Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Miriam Gelabert-Rebato
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Joan A Cadefau
- Department of Biomedicine, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain
| | - Roser Cusso
- Department of Biomedicine, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain; .,Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
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Woelfel JR, Kimball AL, Yen CL, Shields RK. Low-Force Muscle Activity Regulates Energy Expenditure after Spinal Cord Injury. Med Sci Sports Exerc 2017; 49:870-878. [PMID: 28009786 DOI: 10.1249/mss.0000000000001187] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Reduced physical activity is a primary risk factor for increased morbidity and mortality. People with spinal cord injury (SCI) have reduced activity for a lifetime, as they cannot volitionally activate affected skeletal muscles. We explored whether low-force and low-frequency stimulation is a viable strategy to enhance systemic energy expenditure in people with SCI. PURPOSE This study aimed to determine the effects of low stimulation frequency (1 and 3 Hz) and stimulation intensity (50 and 100 mA) on energy expenditure in people with SCI. We also examined the relationship between body mass index and visceral adipose tissue on energy expenditure during low-frequency stimulation. METHODS Ten individuals with complete SCI underwent oxygen consumption monitoring during electrical activation of the quadriceps and hamstrings at 1 and 3 Hz and at 50 and 100 mA. We calculated the difference in energy expenditure between stimulation and rest and estimated the number of days that would be necessary to burn 1 lb of body fat (3500 kcal) for each stimulation protocol (1 vs 3 Hz). RESULTS Both training frequencies induced a significant increase in oxygen consumption above a resting baseline level (P < 0.05). Energy expenditure positively correlated with stimulus intensity (muscle recruitment) and negatively correlated with adiposity (reflecting the insulating properties of adipose tissue). We estimated that 1 lb of body fat could be burned more quickly with 1 Hz training (58 d) as compared with 3 Hz training (87 d) if an identical number of pulses were delivered. CONCLUSION Low-frequency stimulation increased energy expenditure per pulse and may be a feasible option to subsidize physical activity to improve metabolic status after SCI.
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Affiliation(s)
- Jessica R Woelfel
- 1Carver College of Medicine, University of Iowa, Iowa City, IA; and 2Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA
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Neuromuscular fatigue during exercise: Methodological considerations, etiology and potential role in chronic fatigue. Neurophysiol Clin 2017; 47:95-110. [PMID: 28434551 DOI: 10.1016/j.neucli.2017.03.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The term fatigue is used to describe a distressing and persistent symptom of physical and/or mental tiredness in certain clinical populations, with distinct but ultimately complex, multifactorial and heterogenous pathophysiology. Chronic fatigue impacts on quality of life, reduces the capacity to perform activities of daily living, and is typically measured using subjective self-report tools. Fatigue also refers to an acute reduction in the ability to produce maximal force or power due to exercise. The classical measurement of exercise-induced fatigue involves neuromuscular assessments before and after a fatiguing task. The limitations and alternatives to this approach are reviewed in this paper in relation to the lower limb and whole-body exercise, given the functional relevance to locomotion, rehabilitation and activities of daily living. It is suggested that under some circumstances, alterations in the central and/or peripheral mechanisms of fatigue during exercise may be related to the sensations of chronic fatigue. As such, the neurophysiological correlates of exercise-induced fatigue are briefly examined in two clinical examples where chronic fatigue is common: cancer survivors and people with multiple sclerosis. This review highlights the relationship between objective measures of fatigability with whole-body exercise and perceptions of fatigue as a priority for future research, given the importance of exercise in relieving symptoms of chronic fatigue and/or overall disease management. As chronic fatigue is likely to be specific to the individual and unlikely to be due to a simple biological or psychosocial explanation, tailored exercise programmes are a potential target for therapeutic intervention.
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46
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The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise. Eur J Appl Physiol 2017; 117:687-697. [DOI: 10.1007/s00421-017-3561-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/01/2017] [Indexed: 10/20/2022]
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Peoples GE, McLennan PL. Dietary fish oil delays hypoxic skeletal muscle fatigue and enhances caffeine-stimulated contractile recovery in the rat in vivo hindlimb. Appl Physiol Nutr Metab 2017; 42:613-620. [PMID: 28177707 DOI: 10.1139/apnm-2016-0501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxygen efficiency influences skeletal muscle contractile function during physiological hypoxia. Dietary fish oil, providing docosahexaenoic acid (DHA), reduces the oxygen cost of muscle contraction. This study used an autologous perfused rat hindlimb model to examine the effects of a fish oil diet on skeletal muscle fatigue during an acute hypoxic challenge. Male Wistar rats were fed a diet rich in saturated fat (SF), long-chain (LC) n-6 polyunsaturated fatty acids (n-6 PUFA), or LC n-3 PUFA DHA from fish oil (FO) (8 weeks). During anaesthetised and ventilated conditions (normoxia 21% O2 (SaO2-98%) and hypoxia 14% O2 (SaO2-89%)) the hindlimb was perfused at a constant flow and the gastrocnemius-plantaris-soleus muscle bundle was stimulated via sciatic nerve (2 Hz, 6-12V, 0.05 ms) to established fatigue. Caffeine (2.5, 5, 10 mM) was supplied to the contracting muscle bundle via the arterial cannula to assess force recovery. Hypoxia, independent of diet, attenuated maximal twitch tension (normoxia: 82 ± 8; hypoxia: 41 ± 2 g·g-1 tissue w.w.). However, rats fed FO sustained higher peak twitch tension compared with the SF and n-6 PUFA groups (P < 0.05), and the time to decline to 50% of maximum twitch tension was extended (SF: 546 ± 58; n-6 PUFA: 522 ± 58; FO: 792 ± 96 s; P < 0.05). In addition, caffeine-stimulated skeletal muscle contractile recovery was enhanced in the FO-fed animals (SF: 41 ± 3; n-6 PUFA: 40 ± 4; FO: 52 ± 7% recovery; P < 0.05). These results support a physiological role of DHA in skeletal muscle membranes when exposed to low-oxygen stress that is consistent with the attenuation of muscle fatigue under physiologically normoxic conditions.
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Affiliation(s)
- Gregory E Peoples
- School of Medicine, University of Wollongong, Wollongong, 2522, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, 2522, NSW, Australia
| | - Peter L McLennan
- School of Medicine, University of Wollongong, Wollongong, 2522, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, 2522, NSW, Australia
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48
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Sánchez-Duarte E, Trujillo X, Cortés-Rojo C, Saavedra-Molina A, Camargo G, Hernández L, Huerta M, Montoya-Pérez R. Nicorandil improves post-fatigue tension in slow skeletal muscle fibers by modulating glutathione redox state. J Bioenerg Biomembr 2017; 49:159-170. [DOI: 10.1007/s10863-016-9692-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/20/2016] [Indexed: 11/30/2022]
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49
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Black MI, Jones AM, Blackwell JR, Bailey SJ, Wylie LJ, McDonagh STJ, Thompson C, Kelly J, Sumners P, Mileva KN, Bowtell JL, Vanhatalo A. Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains. J Appl Physiol (1985) 2016; 122:446-459. [PMID: 28008101 PMCID: PMC5429469 DOI: 10.1152/japplphysiol.00942.2016] [Citation(s) in RCA: 158] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/12/2016] [Accepted: 12/16/2016] [Indexed: 01/15/2023] Open
Abstract
The gas exchange threshold and the critical power demarcate discrete exercise intensity domains. For the first time, we show that the limit of tolerance during whole body exercise within these domains is characterized by distinct metabolic and neuromuscular responses. Fatigue development during exercise greater than critical power is associated with the attainment of consistent “limiting” values of muscle metabolites, whereas substrate availability and limitations to muscle activation may constrain performance at lower intensities. Lactate or gas exchange threshold (GET) and critical power (CP) are closely associated with human exercise performance. We tested the hypothesis that the limit of tolerance (Tlim) during cycle exercise performed within the exercise intensity domains demarcated by GET and CP is linked to discrete muscle metabolic and neuromuscular responses. Eleven men performed a ramp incremental exercise test, 4–5 severe-intensity (SEV; >CP) constant-work-rate (CWR) tests until Tlim, a heavy-intensity (HVY; <CP but >GET) CWR test until Tlim, and a moderate-intensity (MOD; <GET) CWR test until Tlim. Muscle biopsies revealed that a similar (P > 0.05) muscle metabolic milieu (i.e., low pH and [PCr] and high [lactate]) was attained at Tlim (approximately 2–14 min) for all SEV exercise bouts. The muscle metabolic perturbation was greater at Tlim following SEV compared with HVY, and also following SEV and HVY compared with MOD (all P < 0.05). The normalized M-wave amplitude for the vastus lateralis (VL) muscle decreased to a similar extent following SEV (−38 ± 15%), HVY (−68 ± 24%), and MOD (−53 ± 29%), (P > 0.05). Neural drive to the VL increased during SEV (4 ± 4%; P < 0.05) but did not change during HVY or MOD (P > 0.05). During SEV and HVY, but not MOD, the rates of change in M-wave amplitude and neural drive were correlated with changes in muscle metabolic ([PCr], [lactate]) and blood ionic/acid-base status ([lactate], [K+]) (P < 0.05). The results of this study indicate that the metabolic and neuromuscular determinants of fatigue development differ according to the intensity domain in which the exercise is performed. NEW & NOTEWORTHY The gas exchange threshold and the critical power demarcate discrete exercise intensity domains. For the first time, we show that the limit of tolerance during whole-body exercise within these domains is characterized by distinct metabolic and neuromuscular responses. Fatigue development during exercise greater than critical power is associated with the attainment of consistent “limiting” values of muscle metabolites, whereas substrate availability and limitations to muscle activation may constrain performance at lower intensities.
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Affiliation(s)
- Matthew I Black
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom; and
| | - Andrew M Jones
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Jamie R Blackwell
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Stephen J Bailey
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom; and
| | - Lee J Wylie
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Sinead T J McDonagh
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Christopher Thompson
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - James Kelly
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Paul Sumners
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Katya N Mileva
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Joanna L Bowtell
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Anni Vanhatalo
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom;
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50
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Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability. Sci Rep 2016; 6:39052. [PMID: 27966620 PMCID: PMC5155269 DOI: 10.1038/srep39052] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/16/2016] [Indexed: 01/16/2023] Open
Abstract
After active lengthening contractions, a given amount of force can be maintained with less muscle activation compared to pure isometric contractions at the same muscle length and intensity. This increase in neuromuscular efficiency is associated with mechanisms of stretch-induced residual force enhancement. We hypothesized that stretch-related increase in neuromuscular efficiency reduces fatigability of a muscle during submaximal contractions. 13 subjects performed 60 s isometric knee extensions at 60% of maximum voluntary contraction (MVC) with and without prior stretch (60°/s, 20°). Each 60 s trial was preceded and followed by neuromuscular tests consisting of MVCs, voluntary activation (VA) and resting twitches (RT), and there was 4 h rest between sets. We found a significant (p = 0.036) 10% reduction of quadriceps net-EMG after lengthening compared to pure isometric trials. However, increase in neuromuscular efficiency did not influence the development of fatigue. Albeit we found severe reduction of MVC (30%), RT (30%) and VA (5%) after fatiguing trials, there were no differences between conditions with and without lengthening. As the number of subjects showing no activation reduction increased with increasing contraction time, intensity may have been too strenuous in both types of contractions, such that a distinction between different states of fatigue was not possible anymore.
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