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Cho S, Shaban SM, Song R, Zhang H, Yang D, Kim MJ, Xiong Y, Li X, Madsen K, Wapnick S, Zhang S, Chen Z, Kim J, Guinto G, Li M, Lee M, Nuxoll RF, Shajari S, Wang J, Son S, Shin J, Aranyosi AJ, Wright DE, Kim TI, Ghaffari R, Huang Y, Kim DH, Rogers JA. A skin-interfaced microfluidic platform supports dynamic sweat biochemical analysis during human exercise. Sci Transl Med 2024; 16:eado5366. [PMID: 39231240 DOI: 10.1126/scitranslmed.ado5366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/14/2024] [Accepted: 08/15/2024] [Indexed: 09/06/2024]
Abstract
Blood lactate concentration is an established circulating biomarker for measuring muscle acidity and can be evaluated for monitoring endurance, training routines, or athletic performance. Sweat is an alternative biofluid that may serve similar purposes and offers the advantage of noninvasive collection and continuous monitoring. The relationship between blood lactate and dynamic sweat biochemistry for wearable engineering applications in physiological fitness remains poorly defined. Here, we developed a microfluidic wearable band with an integrated colorimetric timer and biochemical assays that temporally captures sweat and measures pH and lactate concentration. A colorimetric silver nanoplasmonic assay was used to measure the concentration of lactate, and dye-conjugated SiO2 nanoparticle-agarose composite materials supported dynamic pH analysis. We evaluated these sweat biomarkers in relation to blood lactate in human participant studies during cycling exercise of varying intensity. Iontophoresis-generated sweat pH from regions of actively working muscles decreased with increasing heart rate during exercise and was negatively correlated with blood lactate concentration. In contrast, sweat pH from nonworking muscles did not correlate with blood lactate concentration. Changes in sweat pH and blood lactate were observed in participants who did not regularly exercise but not in individuals who regularly exercised, suggesting a relationship to physical fitness and supporting further development for noninvasive, biochemical fitness evaluations.
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Affiliation(s)
- Soongwon Cho
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Samy M Shaban
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Petrochemical Department, Egyptian Petroleum Research Institute, Cairo, 11727, Egypt
| | - Ruihao Song
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Haohui Zhang
- Departments of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Dasom Yang
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Precision Biology Research Center (PBRC), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Min-Jae Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yirui Xiong
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Xiuyuan Li
- Departments of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Kenneth Madsen
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sarena Wapnick
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Shifan Zhang
- Department of Statistics, School of Computer, Data and Information Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ziyu Chen
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Jiwon Kim
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Gianna Guinto
- College of Science and Health, DePaul University, Chicago, IL 60614, USA
| | - Michelle Li
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Minkyu Lee
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Shirley Ryan AbilityLab, Chicago, IL 60611, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL 60611, USA
| | - Ravi F Nuxoll
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Shaghayegh Shajari
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Jin Wang
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - Seongeun Son
- Department of Bionano Engineering, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan, 15588, Republic of Korea
| | - Jihoon Shin
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Alexander J Aranyosi
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Epicore Biosystems, Cambridge, MA 02139, USA
| | | | - Tae-Il Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Roozbeh Ghaffari
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Epicore Biosystems, Cambridge, MA 02139, USA
| | - Yonggang Huang
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Dong-Hwan Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - John A Rogers
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Material Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Neurological Surgery, Northwestern University, Evanston, IL 60208, USA
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Kolodziej F, O’Halloran KD. Re-Evaluating the Oxidative Phenotype: Can Endurance Exercise Save the Western World? Antioxidants (Basel) 2021; 10:609. [PMID: 33921022 PMCID: PMC8071436 DOI: 10.3390/antiox10040609] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/06/2021] [Accepted: 04/10/2021] [Indexed: 01/16/2023] Open
Abstract
Mitochondria are popularly called the "powerhouses" of the cell. They promote energy metabolism through the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, which in contrast to cytosolic glycolysis are oxygen-dependent and significantly more substrate efficient. That is, mitochondrial metabolism provides substantially more cellular energy currency (ATP) per macronutrient metabolised. Enhancement of mitochondrial density and metabolism are associated with endurance training, which allows for the attainment of high relative VO2 max values. However, the sedentary lifestyle and diet currently predominant in the Western world lead to mitochondrial dysfunction. Underdeveloped mitochondrial metabolism leads to nutrient-induced reducing pressure caused by energy surplus, as reduced nicotinamide adenine dinucleotide (NADH)-mediated high electron flow at rest leads to "electron leak" and a chronic generation of superoxide radicals (O2-). Chronic overload of these reactive oxygen species (ROS) damages cell components such as DNA, cell membranes, and proteins. Counterintuitively, transiently generated ROS during exercise contributes to adaptive reduction-oxidation (REDOX) signalling through the process of cellular hormesis or "oxidative eustress" defined by Helmut Sies. However, the unaccustomed, chronic oxidative stress is central to the leading causes of mortality in the 21st century-metabolic syndrome and the associated cardiovascular comorbidities. The endurance exercise training that improves mitochondrial capacity and the protective antioxidant cellular system emerges as a universal intervention for mitochondrial dysfunction and resultant comorbidities. Furthermore, exercise might also be a solution to prevent ageing-related degenerative diseases, which are caused by impaired mitochondrial recycling. This review aims to break down the metabolic components of exercise and how they translate to athletic versus metabolically diseased phenotypes. We outline a reciprocal relationship between oxidative metabolism and inflammation, as well as hypoxia. We highlight the importance of oxidative stress for metabolic and antioxidant adaptation. We discuss the relevance of lactate as an indicator of critical exercise intensity, and inferring from its relationship with hypoxia, we suggest the most appropriate mode of exercise for the case of a lost oxidative identity in metabolically inflexible patients. Finally, we propose a reciprocal signalling model that establishes a healthy balance between the glycolytic/proliferative and oxidative/prolonged-ageing phenotypes. This model is malleable to adaptation with oxidative stress in exercise but is also susceptible to maladaptation associated with chronic oxidative stress in disease. Furthermore, mutations of components involved in the transcriptional regulatory mechanisms of mitochondrial metabolism may lead to the development of a cancerous phenotype, which progressively presents as one of the main causes of death, alongside the metabolic syndrome.
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Affiliation(s)
- Filip Kolodziej
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, T12 XF62 Cork, Ireland;
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Secrets of virtuoso: neuromuscular attributes of motor virtuosity in expert musicians. Sci Rep 2015; 5:15750. [PMID: 26502770 PMCID: PMC4621510 DOI: 10.1038/srep15750] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 10/01/2015] [Indexed: 01/05/2023] Open
Abstract
Musical performance requires extremely fast and dexterous limb movements. The underlying biological mechanisms have been an object of interest among scientists and non-scientists for centuries. Numerous studies of musicians and non-musicians have demonstrated that neuroplastic adaptations through early and deliberate musical training endowed superior motor skill. However, little has been unveiled about what makes inter-individual differences in motor skills among musicians. Here we determined the attributes of inter-individual differences in the maximum rate of repetitive piano keystrokes in twenty-four pianists. Among various representative factors of neuromuscular functions, anatomical characteristics, and training history, a stepwise multiple regression analysis and generalized linear model identified two predominant predictors of the maximum rate of repetitive piano keystrokes; finger tapping rate and muscular strength of the elbow extensor. These results suggest a non-uniform role of individual limb muscles in the production of extremely fast repetitive multi-joint movements. Neither age of musical training initiation nor the amount of extensive musical training before age twenty was a predictor. Power grip strength was negatively related to the maximum rate of piano keystrokes only during the smallest tone production. These findings highlight the importance of innate biological nature and explicit training for motor virtuosity.
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Southern WM, Ryan TE, Kepple K, Murrow JR, Nilsson KR, McCully KK. Reduced skeletal muscle oxidative capacity and impaired training adaptations in heart failure. Physiol Rep 2015; 3:3/4/e12353. [PMID: 25855248 PMCID: PMC4425959 DOI: 10.14814/phy2.12353] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Systolic heart failure (HF) is associated with exercise intolerance that has been attributed, in part, to skeletal muscle dysfunction. The purpose of this study was to compare skeletal muscle oxidative capacity and training-induced changes in oxidative capacity in participants with and without HF. Participants with HF (n = 16, 65 ± 6.6 years) were compared with control participants without HF (n = 23, 61 ± 5.0 years). A subset of participants (HF: n = 7, controls: n = 5) performed 4 weeks of wrist-flexor exercise training. Skeletal muscle oxidative capacity was determined from the recovery kinetics of muscle oxygen consumption measured by near-infrared spectroscopy (NIRS) following a brief bout of wrist-flexor exercise. Oxidative capacity, prior to exercise training, was significantly lower in the HF participants in both the dominant (1.31 ± 0.30 min−1 vs. 1.59 ± 0.25 min−1, P = 0.002; HF and control groups, respectively) and nondominant arms (1.29 ± 0.24 min−1 vs. 1.46 ± 0.23 min−1, P = 0.04; HF and control groups, respectively). Following 4 weeks of endurance training, there was a significant difference in the training response between HF and controls, as the difference in oxidative training adaptations was 0.69 ± 0.12 min−1 (P < 0.001, 95% CI 0.43, 0.96). The wrist-flexor training induced a ∼50% improvement in oxidative capacity in participants without HF (mean difference from baseline = 0.66 ± 0.09 min−1, P < 0.001, 95% CI 0.33, 0.98), whereas participants with HF showed no improvement in oxidative capacity (mean difference from baseline = −0.04 ± 0.08 min−1, P = 0.66, 95% CI −0.24, 0.31), suggesting impairments in mitochondrial biogenesis. In conclusion, participants with HF had reduced oxidative capacity and impaired oxidative adaptations to endurance exercise compared to controls.
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Affiliation(s)
| | | | | | - Jonathan R Murrow
- University of Georgia, Athens, Georgia Georgia Regents University, Athens, Georgia
| | - Kent R Nilsson
- University of Georgia, Athens, Georgia Georgia Regents University, Athens, Georgia
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Boushel R, Lundby C, Qvortrup K, Sahlin K. Mitochondrial plasticity with exercise training and extreme environments. Exerc Sport Sci Rev 2015; 42:169-74. [PMID: 25062000 DOI: 10.1249/jes.0000000000000025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mitochondria form a reticulum in skeletal muscle. Exercise training stimulates mitochondrial biogenesis, yet an emerging hypothesis is that training also induces qualitative regulatory changes. Substrate oxidation, oxygen affinity, and biochemical coupling efficiency may be regulated differentially with training and exposure to extreme environments. Threshold training doses inducing mitochondrial upregulation remain to be elucidated considering fitness level.
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Affiliation(s)
- Robert Boushel
- 1Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden; 2Center for Integrative Human Physiology, Institute of Physiology, University of Zurich, Zurich, Switzerland; and 3Department of Biomedical Sciences, Core Facility for Integrated Microscopy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Larsen RG, Callahan DM, Foulis SA, Kent-Braun JA. In vivo oxidative capacity varies with muscle and training status in young adults. J Appl Physiol (1985) 2009; 107:873-9. [PMID: 19556459 DOI: 10.1152/japplphysiol.00260.2009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well established that exercise training results in increased muscle oxidative capacity. Less is known about how oxidative capacities in distinct muscles, in the same individual, are affected by different levels of physical activity. We hypothesized that 1) trained individuals would have higher oxidative capacity than untrained individuals in both tibialis anterior (TA) and vastus lateralis (VL) and 2) oxidative capacity would be higher in TA than VL in untrained, but not in trained, individuals. Phosphorus magnetic resonance spectroscopy was used to measure the rate of phosphocreatine recovery (k(PCr)), which reflects the rate of oxidative phosphorylation, following a maximal voluntary isometric contraction of the TA and VL in healthy untrained (7 women, 7 men, 25.7 +/- 3.6 yr; mean +/- SD) and trained (5 women, 7 men, 27.5 +/- 3.4 yr) adults. Daily physical activity levels were measured using accelerometry. The trained group spent threefold more time ( approximately 90 vs. approximately 30 min/day; P < 0.001) in moderate to vigorous physical activity (MVPA). Overall, k(PCr) was higher in VL than in TA (P = 0.01) and higher in trained than in untrained participants (P < 0.001). The relationship between k(PCr) and MVPA was more robust in VL (r = 0.64, P = 0.001, n = 25) than in TA (r = 0.38, P = 0.06, n = 25). These results indicate greater oxidative capacity in vivo in trained compared with untrained individuals in two distinct muscles of the lower limb and provide novel evidence of higher oxidative capacity in VL compared with TA in young humans, irrespective of training status. The basis for this difference is not known at this time but likely reflects a difference in usage patterns between the muscles.
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Affiliation(s)
- Ryan G Larsen
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Kanayama T, Minowa K, Inoue N, Yamaguchi T, Tamura T, Yoshida S, Kawasaki T. Comparison of phosphocreatine concentration in the human masseter and medial pterygoid muscles by 31P-CSI. J Oral Rehabil 2008. [DOI: 10.1111/j.1365-2842.2001.00777.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Walker TB, Altobelli SA, Caprihan A, Robergs RA. Failure of Rhodiola rosea to alter skeletal muscle phosphate kinetics in trained men. Metabolism 2007; 56:1111-7. [PMID: 17618958 DOI: 10.1016/j.metabol.2007.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Accepted: 04/04/2007] [Indexed: 11/16/2022]
Abstract
Rhodiola rosea is an herbal supplement purported to improve resistance to stressors and to enhance physical performance, potentially by improving adenosine triphosphate (ATP) turnover. Phosphocreatine (PCr) kinetics serves as a reflection of ATP turnover. The purpose of this investigation was to examine the effect of R rosea ingestion on human skeletal muscle PCr recovery after exhaustive exercise. Twelve resistance-trained men, aged 19 to 39 years, completed incremental forearm wrist flexion exercise to volitional fatigue, once after ingesting 1500 mg R rosea per day for 4 days, and once after ingesting an equivalent placebo dose. During exercise and recovery from exercise, muscle phosphates were examined using phosphorus 31 nuclear magnetic resonance spectroscopy. [PCr] during recovery was fit with a monoexponential function, and the resulting rate constants (k) were compared between groups. Rating of perceived exertion per stage and time to exhaustion were also compared between groups. For R rosea, k=0.3744+/-0.1532, whereas for placebo, k=0.3956+/-0.2238. Although rating of perceived exertion significantly increased within groups as workload increased, it did not differ between conditions, nor did time to exhaustion (R rosea, 10.71+/-0.54 minutes; placebo, 10.48+/-0.68 minutes). Estimates of [PCr] at time 0, 5, 10, 15, and 20 minutes of recovery were nearly identical between groups. In summary, there were no significant differences between groups for any of theparameters measured. Based on these results, we conclude that R rosea ingestion does not improve ATP turnover during or immediately after exercise.
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Affiliation(s)
- Thomas B Walker
- Biosciences and Protection Division, Air Force Research Laboratory, Brooks City-Base, TX 78235, USA.
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Jones AM, Wilkerson DP, Berger NJ, Fulford J. Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise. Am J Physiol Regul Integr Comp Physiol 2007; 293:R392-401. [PMID: 17475681 DOI: 10.1152/ajpregu.00056.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 +/- 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 +/- 2.3 min vs. postintervention group (POST): 19.4 +/- 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 +/- 1.6 min vs. POST: 22.0 +/- 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 +/- 13 s vs. POST: 43 +/- 10 s) or the trained leg (PRE: 38 +/- 8 s vs. POST: 40 +/- 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 +/- 7 vs. POST: 7 +/- 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 +/- 8 vs. POST: 12 +/- 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.
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Affiliation(s)
- Andrew M Jones
- School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, UK.
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Hug F, Grélot L, Le Fur Y, Cozzone PJ, Bendahan D. Recovery kinetics throughout successive bouts of various exercises in elite cyclists. Med Sci Sports Exerc 2007; 38:2151-8. [PMID: 17146323 DOI: 10.1249/01.mss.0000235882.86734.9a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE In the present study we investigated whether a high volume of cycling training would influence the metabolic changes associated with a succession of three exhaustive cycling exercises. METHODS Seven professional road cyclists (VO2max: 74.3 +/- 3.7 mL.min.kg; maximal power tolerated: 475 +/- 18 W; training: 22 +/- 3 h.wk) and seven sport sciences students (VO2max: 54.2 +/- 5.3 mL.min.kg; maximal power tolerated: 341 +/- 26 W; training: 6 +/- 2 h.wk) performed three different exhaustive cycling exercise bouts (progressive, constant load, and sprint) on an electrically braked cycloergometer positioned near the magnetic resonance scanner. Less than 45 s after the completion of each exercise bout, recovery kinetics of high-energy phosphorylated compounds and pH were measured using P-MR spectroscopy. RESULTS Resting values for phosphomonoesters (PME) and phosphodiesters (PDE) were significantly elevated in the cyclist group (PME/ATP: 0.82 +/- 0.11 vs 0.58 +/- 0.19; PDE/ATP: 0.27 +/- 0.03 vs 0.21 +/- 0.05). Phosphocreatine (PCr) consumption and inorganic phosphate (Pi) accumulation measured at end of exercise bouts 1 (PCr: 6.5 +/- 3.2 vs 10.4 +/- 1.6 mM; Pi: 1.6 +/- 0.7 vs 6.8 +/- 3.4 mM) and 3 (PCr: 5.6 +/- 2.4 vs 9.3 +/- 3.9 mM; Pi: 1.5 +/- 0.5 vs 7.7 +/- 3.3 mM) were reduced in cyclists compared with controls. During the recovery period after each exercise bout, the pH-recovery rate was larger in professional road cyclists, whereas the PCr-recovery kinetics were significantly faster for cyclists only for bout 3. DISCUSSION Whereas the PDE and PME elevation at rest in professional cyclists may indicate fiber-type changes and an imbalance between glycogenolytic and glycolytic activity, the lower PCr consumption during exercise and the faster pH-recovery kinetic clearly suggest an improved mitochondrial function.
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Affiliation(s)
- François Hug
- University of Nantes, Nantes Atlantic Universities, Laboratory of Motricity, Interactions, and Performance, Nantes, France.
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Hug F, Bendahan D, Le Fur Y, Cozzone PJ, Grélot L. Metabolic Recovery in Professional Road Cyclists: A 31P-MRS Study. Med Sci Sports Exerc 2005; 37:846-52. [PMID: 15870640 DOI: 10.1249/01.mss.0000162616.20085.b4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Aerobic training of professional road cyclists is linked to tremendous aerobic capacities that have never been clearly related to what occur in skeletal muscles submitted to a specific exercise. The aim of the present study was to examine specifically metabolic recovery after an incremental cycling exercise performed until exhaustion in professional road cyclists as compared with moderately trained subjects and so using 31P- MRS. METHODS Subjects performed a progressive cycling exercise on a cycloergometer until exhaustion, then they were positioned back in the magnet (delay lower than 45 s) for recovery scanning. 31P spectra of thigh muscles were time averaged in 2-s blocks at rest and for 15 min throughout the recovery period. RESULTS For a significantly more intense exercise (477 +/- 28 vs 334 +/- 24 W in controls; P < 0.001), professional road cyclists displayed similar end-of-exercise extrapolated pH values (6.43 +/- 0.16 vs. 6.34 +/- 0.05 in controls) and a significantly higher PCr concentration (20.1 +/- 0.8 vs. 13.3 +/- 0.5 mM in controls, P < 0.001). The pH recovery kinetics provided the evidence of metabolic adaptations related to a specific training in professional cyclists with a significantly faster rate (P < 0.01) of pH return toward basal values (32.8 +/- 18.9 vs 10.8 +/- 6.7 mM x min(-1)). On the contrary, no significant difference was measured for the PCr recovery kinetics. At rest, PDE concentration was significantly higher in professional cyclists (2.50 +/- 0.80 vs 1.76 +/- 0.42 mM), likely indicating a difference regarding fiber-type composition. DISCUSSION The present data demonstrated for the first time that the tremendous aerobic capacity in professional cyclists is linked to faster pH recovery kinetics after a specific cycling exercise.
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Affiliation(s)
- François Hug
- Department of Sport Physiology, Faculty of Sport Sciences, IFR Marey, University of the Mediteranean (Aix-Marseille II), Marseille, France.
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Kobayashi Y, Takeuchi T, Hosoi T, Loeppky JA. Effects of habitual smoking on cardiorespiratory responses to sub-maximal exercise. ACTA ACUST UNITED AC 2004; 23:163-9. [PMID: 15472461 DOI: 10.2114/jpa.23.163] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The effects of habitual cigarette smoking on cardiorespiratory responses to sub-maximal and maximal work were evaluated in nine adult nonsmokers and nine smokers with a mean age of 33 yr. A maximal treadmill test was followed by three tests at 45, 60 and 75% of each subject's VO(2)max. Compared to nonsmokers, the habitual smokers had a non-significantly lower VO(2)max in L/min and per lean body mass (9 and 6%, respectively), but had higher %fat (p<0.01), resulting in a significantly lower VO(2)max per kg body wt (13%, p<0.03). Maximal exercise ventilation (V(E)) was 16% lower in smokers. During sub-maximal work at equivalent exercise stress levels in the two groups, the V(E)/VO(2) ratio was higher in smokers by an average of 11% because VO(2) was lower and the respiratory exchange ratio values were significantly elevated in smokers at 75% of VO(2)max. Blood lactate concentrations in smokers were higher as workloads increased and O(2) pulse (VO(2)/HR) was significantly lower throughout, indicating reduced O(2) extraction, probably due to carbon monoxide. The resting HR was significantly higher in smokers and the HR recovery following all three submaximal exercises was significantly slower in smokers. These results show that detrimental cardiorespiratory effects of chronic cigarette smoking in apparently healthy individuals are evident at moderate exercise levels as reduced gas exchange efficiency in lungs and muscles.
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Affiliation(s)
- Yoshio Kobayashi
- The Laboratory for Health and Human Performance, School of Arts and Sciences, Chukyo University, Nagoya, Japan.
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Aronchik I, Behne MJ, Leypoldt L, Crumrine D, Epstein E, Ikeda S, Mizoguchi M, Bench G, Pozzan T, Mauro T. Actin reorganization is abnormal and cellular ATP is decreased in Hailey-Hailey keratinocytes. J Invest Dermatol 2003; 121:681-7. [PMID: 14632182 DOI: 10.1046/j.1523-1747.2003.12472.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Actin reorganization and the formation of adherens junctions are necessary for normal cell-to-cell adhesion in keratinocytes. Hailey-Hailey disease (HHD) is blistering skin disease, resulting from mutations in the Ca2+ ATPase ATP2C1, which controls Ca2+ concentrations in the cytoplasm and Golgi of human keratinocytes. Because actin reorganization is among the first responses to raised cytoplasmic Ca2+, we examined Ca2+-induced actin reorganization in normal and HHD keratinocytes. Even though HHD keratinocytes display raised baseline cytoplasmic Ca2+, we found that actin reorganization in response to Ca2+ was impaired in HHD keratinocytes. Defects in actin reorganization were linked to a marked decrease in cellular ATP in HHD keratinocytes, which persists, in vivo, in HHD epidermis. Defective actin reorganization was reproduced in normal keratinocytes in which the intracellular ATP concentration had been lowered pharmacologically. ATP concentrations in undifferentiated keratinocytes markedly declined after extracellular Ca2+ was increased, but then recovered to a new baseline that was approximately 150% of the previous baseline. In contrast, ATP concentrations in HHD keratinocytes did not change in response to increased extracellular Ca2+. This report provides new insights into how the ATP2C1-controlled ATP metabolism mediates Ca2+-induced cell-to-cell adhesion in normal keratinocytes. In addition, these findings implicate inadequate ATP stores as an additional cause in the pathogenesis of HHD and suggest novel therapeutic options.
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Affiliation(s)
- Ida Aronchik
- Department of Dermatology, University of California, San Francisco, California, USA
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14
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Zoll J, Sanchez H, N'Guessan B, Ribera F, Lampert E, Bigard X, Serrurier B, Fortin D, Geny B, Veksler V, Ventura-Clapier R, Mettauer B. Physical activity changes the regulation of mitochondrial respiration in human skeletal muscle. J Physiol 2002; 543:191-200. [PMID: 12181291 PMCID: PMC2290497 DOI: 10.1113/jphysiol.2002.019661] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study explores the importance of creatine kinase (CK) in the regulation of muscle mitochondrial respiration in human subjects depending on their level of physical activity. Volunteers were classified as sedentary, active or athletic according to the total activity index as determined by the Baecke questionnaire in combination with maximal oxygen uptake values (peak V(O2), expressed in ml min(-1) kg(-1)). All volunteers underwent a cyclo-ergometric incremental exercise test to estimate their peak V(O2) and V(O2) at the ventilatory threshold (VT). Muscle biopsy samples were taken from the vastus lateralis and mitochondrial respiration was evaluated in an oxygraph cell on saponin permeabilised muscle fibres in the absence (V(0)) or in the presence (V(max)) of saturating [ADP]. While V(0) was similar, V(max) differed among groups (sedentary, 3.7 +/- 0.3, active, 5.9 +/- 0.9 and athletic, 7.9 +/- 0.5 micromol O2 min(-1) (g dry weight)(-1)). V(max) was correlated with peak V(O2) (P < 0.01, r = 0.63) and with V(T) (P < 0.01, r = 0.57). There was a significantly greater degree of coupling between oxidation and phosphorylation (V(max)/V(0)) in the athletic individuals. The mitochondrial K(m) for ADP was significantly higher in athletic subjects (P < 0.01). Mitochondrial CK (mi-CK) activation by addition of creatine induced a marked decrease in K(m) in athletic individuals only, indicative of an efficient coupling of mi-CK to ADP rephosphorylation in the athletic subjects only. It is suggested that increasing aerobic performance requires an enhancement of both muscle oxidative capacity and mechanisms of respiratory control, attesting to the importance of temporal co-ordination of energy fluxes by CK for higher efficacy.
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Affiliation(s)
- J Zoll
- Département de Physiologie, Equipe d'Accueil 3072, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
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15
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Echegaray M, Rivera MA. Role of creatine kinase isoenzymes on muscular and cardiorespiratory endurance: genetic and molecular evidence. Sports Med 2002; 31:919-34. [PMID: 11708401 DOI: 10.2165/00007256-200131130-00003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The ability to perform well in activities that require muscular and cardiorespiratory endurance is a trait influenced, in a considerable part, by the genetic make-up of individuals. Early studies of performance and recent scans of the human genome have pointed at various candidate genes responsible for the heterogeneity of these phenotypes within the population. Among these are the genes for the various creatine kinase (CK) isoenzyme subunits. CK and phosphocreatine (PCr) form an important metabolic system for temporal and spatial energy buffering in cells with large variations in energy demand. The different CK isoenzyme subunits (CK-M and CK-B) are differentially expressed in the tissues of the body. Although CK-M is the predominant form in both skeletal and cardiac muscle, CK-B is expressed to a greater extent in heart than in skeletal muscle. Studies in humans and mice have shown that the expression of CK-B messenger RNA (mRNA) and the abundance and activity of the CK-MB dimer increase in response to cardiorespiratory endurance training. Increases in muscle tissue CK-B content can be energetically favourable because of its lower Michaelis constant (Km) for ADP. The activity of the mitochondrial isoform of CK (Scmit-CK) has also been significantly and positively correlated to oxidative capacity and to CK-MB activity in muscle. In mice where the CK-M gene has been knocked out, significant increases in fatigue resistance together with cellular adaptations increasing aerobic capacity have been observed. These observations have led to the notion that this enzyme may be responsible for fatigue under normal circumstances, most likely because of the local cell compartment increase in inorganic phosphate concentration. Studies where the Scmit-CK gene was knocked out have helped demonstrate that this isoenzyme is very important for the stimulation of aerobic respiration. Human studies of CK-M gene sequence variation have shown a significant association between a polymorphism, distinguished by the NcoI restriction enzyme, and an increase in cardiorespiratory endurance as indexed by maximal oxygen uptake following 20 weeks of training. In conclusion, there is now evidence at the tissue, cell and molecular level indicating that the CK-PCr system plays an important role in determining the phenotypes of muscular and cardiorespiratory endurance. It is envisioned that newer technologies will help determine how the genetic variability of these genes (and many others) impact on performance and health-related phenotypes.
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Affiliation(s)
- M Echegaray
- Department of Biology, University of Puerto Rico at Cayey.
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16
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Eastwood PR, Hillman DR, Finucane KE. Inspiratory muscle performance in endurance athletes and sedentary subjects. Respirology 2001; 6:95-104. [PMID: 11422888 DOI: 10.1046/j.1440-1843.2001.00314.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The aim of this study was to determine whether whole-body endurance training is associated with increased respiratory muscle strength and endurance. METHODOLOGY Respiratory muscle strength (maximum inspiratory pressure (PImax)) and endurance (progressive threshold loading of the inspiratory muscles) were measured in six marathon runners and six sedentary subjects. RESULTS PImax was similar between the two groups of subjects but the maximum threshold pressure achieved was greater in marathon runners (90 +/- 8 vs 78 +/- 10% of PImax, respectively, mean +/- SD, P < 0.05). During progressive threshold loading, marathon runners breathed with lower frequency, higher tidal volume, and longer inspiratory and expiratory time. At maximum threshold pressure, marathon runners had lower arterial O2 saturation, but perceived effort (Borg scale) was maximal in both groups. Efficiency of the respiratory muscles was similar in both groups being 2.0 +/- 1.7% and 2.3 +/- 1.8% for marathon runners and sedentary subjects, respectively. CONCLUSIONS The apparent increase in respiratory muscle endurance of athletes was a consequence of a difference in the breathing pattern adopted during loaded breathing rather than respiratory muscle strength or efficiency. This implies that sensory rather than respiratory muscle conditioning may be an important mechanism by which whole-body endurance is increased.
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Affiliation(s)
- P R Eastwood
- Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.
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17
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Tomlin DL, Wenger HA. The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Med 2001; 31:1-11. [PMID: 11219498 DOI: 10.2165/00007256-200131010-00001] [Citation(s) in RCA: 300] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A strong relationship between aerobic fitness and the aerobic response to repeated bouts of high intensity exercise has been established, suggesting that aerobic fitness is important in determining the magnitude of the oxidative response. The elevation of exercise oxygen consumption (VO2) is at least partially responsible for the larger fast component of excess post-exercise oxygen consumption (EPOC) seen in endurance-trained athletes following intense intermittent exercise. Replenishment of phosphocreatine (PCr) has been linked to both fast EPOC and power recovery in repeated efforts. Although 31P magnetic resonance spectroscopy studies appear to support a relationship between endurance training and PCr recovery following both submaximal work and repeated bouts of moderate intensity exercise, PCr resynthesis following single bouts of high intensity effort does not always correlate well with maximal oxygen consumption (VO2max). It appears that intense exercise involving larger muscle mass displays a stronger relationship between VO2max and PCr resynthesis than does intense exercise utilising small muscle mass. A strong relationship between power recovery and endurance fitness, as measured by the percentage VO2max corresponding to a blood lactate concentration of 4 mmol/L, has been demonstrated. The results from most studies examining power recovery and VO2max seem to suggest that endurance training and/or a higher VO2max results in superior power recovery across repeated bouts of high intensity intermittent exercise. Some studies have supported an association between aerobic fitness and lactate removal following high intensity exercise, whereas others have failed to confirm an association. Unfortunately, all studies have relied on measurements of blood lactate to reflect muscle lactate clearance, and different mathematical methods have been used for assessing blood lactate clearance, which may compromise conclusions on lactate removal. In summary, the literature suggests that aerobic fitness enhances recovery from high intensity intermittent exercise through increased aerobic response, improved lactate removal and enhanced PCr regeneration.
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Affiliation(s)
- D L Tomlin
- University of Victoria, British Columbia, Canada.
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18
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Park JH, Niermann KJ, Ryder NM, Nelson AE, Das A, Lawton AR, Hernanz-Schulman M, Olsen NJ. Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies. ARTHRITIS AND RHEUMATISM 2000; 43:2359-67. [PMID: 11037897 DOI: 10.1002/1529-0131(200010)43:10<2359::aid-anr25>3.0.co;2-d] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To characterize metabolic abnormalities in the muscles of children with the juvenile variant of dermatomyositis (JDM) by the use of noninvasive P-31 magnetic resonance spectroscopy (MRS). METHODS Thirteen patients with JDM (ages 4-16 years) were studied. Biochemical status was evaluated with P-31 MRS by determining the concentrations of the high-energy phosphate compounds, ATP and phosphocreatine (PCr), ratios of inorganic phosphate (Pi) to PCr (Pi:PCr ratio), levels of free cytosolic ADP, and phosphorylation potentials (PPs) during rest, exercise, and recovery. RESULTS Significant metabolic abnormalities were observed in the thigh muscles of 10 severely affected patients during rest, 2 graded levels of exercise, and recovery. Mean ATP and PCr levels in the muscles of JDM patients were 35-40% below the normal control values (P < 0.003). These data, along with elevated Pi:PCr ratios, higher ADP levels, and abnormal values for PPs, indicated defective oxidative phosphorylation in the mitochondria of diseased JDM muscles. MRS findings were normal in 2 additional patients who had improved with prednisone treatment and in 1 patient who had no muscle weakness (amyopathic variant of JDM). CONCLUSION JDM patients can be monitored with noninvasive P-31 MRS without sedation. Biochemical defects in energy metabolism are concordant with the weakness and fatigue reported by JDM patients. Quantitative MRS data are useful for evaluating patients and optimizing drug treatment regimens.
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Affiliation(s)
- J H Park
- Vanderbilt University Medical School, Nashville, Tennessee 37232, USA
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19
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Heerschap A, Houtman C, in 't Zandt HJ, van den Bergh AJ, Wieringa B. Introduction to in vivo 31P magnetic resonance spectroscopy of (human) skeletal muscle. Proc Nutr Soc 1999; 58:861-70. [PMID: 10817153 DOI: 10.1017/s0029665199001160] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
31P magnetic resonance spectroscopy (MRS) offers a unique non-invasive window on energy metabolism in skeletal muscle, with possibilities for longitudinal studies and of obtaining important bioenergetic data continuously and with sufficient time resolution during muscle exercise. The present paper provides an introductory overview of the current status of in vivo 31P MRS of skeletal muscle, focusing on human applications, but with some illustrative examples from studies on transgenic mice. Topics which are described in the present paper are the information content of the 31P magnetic resonance spectrum of skeletal muscle, some practical issues in the performance of this MRS methodology, related muscle biochemistry and the validity of interpreting results in terms of biochemical processes, the possibility of investigating reaction kinetics in vivo and some indications for fibre-type heterogeneity as seen in spectra obtained during exercise.
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Affiliation(s)
- A Heerschap
- Department of Radiology, Faculty of Medical Sciences, University of Nijmegen, The Netherlands.
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20
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Park JH, Phothimat P, Oates CT, Hernanz-Schulman M, Olsen NJ. Use of P-31 magnetic resonance spectroscopy to detect metabolic abnormalities in muscles of patients with fibromyalgia. ARTHRITIS AND RHEUMATISM 1998; 41:406-13. [PMID: 9506567 DOI: 10.1002/1529-0131(199803)41:3<406::aid-art5>3.0.co;2-l] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To investigate the metabolic and functional status of muscles of fibromyalgia (FM) patients, using P-31 magnetic resonance spectroscopy (MRS). METHODS Twelve patients with FM and 11 healthy subjects were studied. Clinical status was assessed by questionnaire. Biochemical status of muscle was evaluated with P-31 MRS by determining concentrations of inorganic phosphate (Pi), phosphocreatine (PCr), ATP, and phosphodiesters during rest and exercise. Functional status was evaluated from the PCr/Pi ratio, phosphorylation potential (PP), and total oxidative capacity (Vmax). RESULTS Patients with FM reported greater difficulty in performing activities of daily living as well as increased pain, fatigue, and weakness compared with controls. MRS measurements showed that patients had significantly lower than normal PCr and ATP levels (P < 0.004) and PCr/Pi ratios (P < 0.04) in the quadriceps muscles during rest. Values for PP and Vmax also were significantly reduced during rest and exercise. CONCLUSION P-31 MRS provides objective evidence for metabolic abnormalities consistent with weakness and fatigue in patients with FM. Noninvasive P-31 MRS may be useful in assessing clinical status and evaluating the effectiveness of treatment regimens in FM.
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Affiliation(s)
- J H Park
- Department of Radiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2681, USA
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21
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Lodi R, Kemp GJ, Iotti S, Radda GK, Barbiroli B. Influence of cytosolic pH on in vivo assessment of human muscle mitochondrial respiration by phosphorus magnetic resonance spectroscopy. MAGMA (NEW YORK, N.Y.) 1997; 5:165-71. [PMID: 9268081 DOI: 10.1007/bf02592248] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The authors present an in vivo phosphorus magnetic resonance spectroscopy systematic study on the effects of cytosolic pH on skeletal muscle mitochondrial respiration in human calf muscle. In 49 normal subjects, the effect of cytosolic pH on kinetics of phosphocreatine and adenosine diphosphate recovery and on maximum rate of mitochondrial adenosine triphosphate production (Q(MAX)) was evaluated. The results show a strong relationship between the rate of postexercise phosphocreatine recovery and the lowest value of cytosolic pH reached during recovery from exercise (termed minimum pH; r = 0.89); in contrast, both adenosine diphosphate recovery halftime and Q(MAX) were independent of cytosolic pH at the end of exercise.
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Affiliation(s)
- R Lodi
- Cattedra di Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia Applicata D. Campanacci, Universitá di Bologna, Italy
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22
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Guthrie BM, Frostick SP, Goodman J, Mikulis DJ, Plyley MJ, Marshall KW. Endurance-trained and untrained skeletal muscle bioenergetics observed with magnetic resonance spectroscopy. CANADIAN JOURNAL OF APPLIED PHYSIOLOGY = REVUE CANADIENNE DE PHYSIOLOGIE APPLIQUEE 1996; 21:251-63. [PMID: 8853467 DOI: 10.1139/h96-022] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Resting and submaximal isometric exercise 31P magnetic resonance spectroscopy (MRS) was carried out on 7 endurance-trained males (26.0 +/- 3 yrs) and 7 sedentary males (27.0 +/- 4 yrs). Spectral analysis provided peak areas of phosphocreatine (PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP), and the chemical shift of Pi relative to PCr. The ratio of PCr/Pi was moderately lower during rest (preexercise p = .13, postexercise p = .18), and significantly higher during exercise (p < .05) in the trained subjects. Intracellular pH patterns were the same for both groups; a transient alkalosis was observed at the onset of exercise with a return to resting levels after 2 min. Differences suggest improved ATP resynthesis rate in the trained subjects during exercise. Intracellular pH changes can be attributed to the utilization of hydrogen ions that accompany PCr hydrolysis during work. The findings are congruent with previous reports indicating a superior oxidative capacity in trained skeletal muscle.
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Affiliation(s)
- B M Guthrie
- Human Kinetics, Champaign, IL 61825-5076, USA
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23
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Mattila KT, Komu M, Karsikas R, Hatakka P, Heinonen OJ, Kormano M. Knee extension dynamometer: a new device for dynamic isokinetic magnetic resonance spectroscopy experiments. MAGMA (NEW YORK, N.Y.) 1996; 4:115-22. [PMID: 8875397 DOI: 10.1007/bf01772518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In the present study we introduce a new device for exercise magnetic resonance spectroscopy (MRS). It operates in a standard whole-body scanner. Mechanical exertion unit allows maximal 10 degrees to 15 degrees short-arc knee extensions. The device operates hydraulically and is based on isokinetic movement. The force and work conducted are automatically controlled by the electronic control and computer unit. A small surface coil placed on the vastus medialis muscle allows the collection of spectra without interfering spectra from nearby resting muscles. The force used for the extensions can be followed simultaneously as a curve on the screen in the operator's room and the data is transferred to a personal computer for later analysis. Total work and fatigue percentage are also calculated by the device. It also allows the use of different isokinetic exercise protocols. The measurements of force proved reliable in repeat measurements using an isokinetic test device as a control. This device has been used clinically for over a year, is easy to operate, and offers reliable measurements. It is well suited to trials where muscle energy states versus time are followed since it allows noninvasive simultaneous quantification of muscle performance and collecting MRS spectra at rest, during exercise, and in the recovery phase.
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Affiliation(s)
- K T Mattila
- Department of Diagnostic Radiology, University of Turku, Finland
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24
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Chang C, Chew W, Decrespigny AJ, Alcantara M, McNeill C, Miller AJ. Effect of maturation on 31P magnetic resonance spectroscopy of the rabbit masseter muscle. J Dent Res 1995; 74:1861-9. [PMID: 8600182 DOI: 10.1177/00220345950740120901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
This work studies the dynamic metabolic changes of the rabbit masseter muscle during post-natal development. The composition and proportion of oxidative and glycolytic muscle fibers alter during maturation. The masseter muscle, as most muscles of the craniofacial region, exhibits unusual development in composition of isoforms of myosin. The effect of this unusual composition on the dynamic metabolic properties of the masseter muscle have not been assessed. The metabolism of the rabbit masseter muscle was studied by means of 31P-nuclear magnetic resonance (NMR) spectroscopy. Contraction was elicited by electrical stimulation of the muscle in the anesthetized animal. Five animals were studied at 8 weeks and 24 weeks so that both the juvenile and adult stages could be evaluated. The dynamic biochemical changes in the masseter muscle were studied by the analysis of NMR spectra. A single-turn surface coil (copper) was used, and the original signal was treated with Fourier transforms to obtain 31P spectra. The low signal-to-noise ratio required averaging 16 acquisitions (acquisition time = 400 msec, repetition rate = 1.8 sec) in 30 sec and then obtaining continuous spectra for 27 min. Each averaged spectrum demonstrated five peaks: inorganic phosphate (Pi), creatine phosphate (PCr), and three peaks related to adenosine triphosphate (ATP). The protocol involved recording an initial three-minute rest period, stimulating the muscle at 5 Hz for 3 min twice, separated by three-minute rest periods, and stimulating the muscle at 50 Hz twice for 3 min separated by rest periods. The Pi/PCr ratio increased significantly in the adult masseter during both 5-Hz stimulations, evoking twitching, and the first 50-Hz stimulation, evoking tetany (repeated ANOVA, P < 0.05). The resting pH (6.96 +/- 0.13) was significantly lowered during both twitching (6.85 +/- 0.10; P < 0.0038) and tetany (6.55 +/- 0.13; P < 0.0001), but only in the adult masseter muscle. These finding suggest that the adult masseter muscle possesses more glycolytic fibers as it modifies its metabolism during postnatal development.
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Affiliation(s)
- C Chang
- Department of Growth and Development, School of Medicine, University of California, SanFrancisco, 94143 USA
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25
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Chang C, Alcantara M, DeCrespigny AJ, Chew W, McNeill C, Miller AJ. Plasticity of craniomandibular muscle function: 31P magnetic resonance spectroscopy of the rabbit masseter muscle. Am J Orthod Dentofacial Orthop 1995; 108:168-79. [PMID: 7625392 DOI: 10.1016/s0889-5406(95)70080-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The masseter muscle was studied during postnatal development of the rabbit from the juvenile to adult stage in which the oral function was altered during maturation by modifying the diet to soft food. The muscle was assessed using phosphate magnetic resonance (31P NMR) spectroscopy with a single-turn copper surface coil to study potential changes in phosphate metabolism. The 31P NMR spectra consisted of five peaks related to unbound forms of inorganic phosphate (Pi), creatine phosphate (PCr), and three peaks related to the adenosine triphosphate (ATP). The masseter was assessed in one group of five rabbits at 8 weeks postnatally (juvenile) and after 4 months of this experimental group masticating on soft food. They were compared with a control group of five rabbits raised on a normal hard diet. The Pi/PCr ratio increased in the adult masseter much higher during twitching, tetany, and periodic contraction than in the juvenile regardless as to whether the adult animal had been raised from the juvenile period on soft or hard diet. There were relatively few differences between the experimental adult animals raised on a soft diet and the normal adult animals despite the soft diet animals demonstrating a significantly lower weight and smaller muscle mass. These findings suggest that chronic underuse of the masseter muscle by decreasing the masticatory loads has a minimal effect on the phosphate metabolism of the maturing masseter.
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Affiliation(s)
- C Chang
- Department of Growth and Development, University of California at San Francisco, USA
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26
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Miller RG, Carson PJ, Moussavi RS, Green A, Baker A, Boska MD, Weiner MW. Factors which influence alterations of phosphates and pH in exercising human skeletal muscle: measurement error, reproducibility, and effects of fasting, carbohydrate loading, and metabolic acidosis. Muscle Nerve 1995; 18:60-7. [PMID: 7799999 DOI: 10.1002/mus.880180109] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous studies have shown considerable variability in the metabolic response of human skeletal muscle during a standardized exercise protocol. The goal of these studies was to investigate the factors responsible for the broad range of metabolic changes produced by fatiguing exercise. Experiments were performed to quantitate the measurement error of 31P nuclear magnetic resonance spectroscopy of human muscle, the reproducibility of changes within a single subject, and the effects of fasting, carbohydrate loading, and metabolic acidosis. The results show that none of these factors appear to be responsible for the wide variation between subjects. However, the effects of training and genetic factors were not investigated and are likely to be responsible for the substantial variability between subjects.
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Affiliation(s)
- R G Miller
- Department of Neurology, California Pacific Medical Center, San Francisco 94118
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27
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Park JH, Olsen NJ, King L, Vital T, Buse R, Kari S, Hernanz-Schulman M, Price RR. Use of magnetic resonance imaging and P-31 magnetic resonance spectroscopy to detect and quantify muscle dysfunction in the amyopathic and myopathic variants of dermatomyositis. ARTHRITIS AND RHEUMATISM 1995; 38:68-77. [PMID: 7818575 DOI: 10.1002/art.1780380111] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE To investigate the use of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in characterizing the metabolic and functional status of muscles in patients with amyopathic dermatomyositis (DM) and to compare the findings with those in patients with classic myopathic DM. METHODS Nine patients with amyopathic DM, 11 patients with myopathic DM, and 11 normal individuals were studied. MRI images of thigh muscles were obtained, and T1 and T2 relaxation times were calculated. Biochemical status was quantitated with P-31 MRS, by determining concentrations of phosphate metabolites during rest and exercise. RESULTS Patients with amyopathic DM showed no muscle inflammation, and MRS data obtained during rest were normal. During exercise at 25% and 50% maximum voluntary contractile force, the MRS data revealed significant differences between amyopathic DM patients and control subjects indicating inefficient metabolism. In contrast, muscles of patients with myopathic DM showed inflammation and metabolic abnormalities even during rest. CONCLUSION Metabolic deficiencies in patients with amyopathic DM were unmasked by exercise, suggesting that the 2 DM syndromes may share muscle abnormalities. MRI/MRS may be useful in diagnosis and optimization of treatment.
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Affiliation(s)
- J H Park
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
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28
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Park JH, Vital TL, Ryder NM, Hernanz-Schulman M, Partain CL, Price RR, Olsen NJ. Magnetic resonance imaging and P-31 magnetic resonance spectroscopy provide unique quantitative data useful in the longitudinal management of patients with dermatomyositis. ARTHRITIS AND RHEUMATISM 1994; 37:736-46. [PMID: 8185702 DOI: 10.1002/art.1780370519] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To evaluate the utility of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in the longitudinal management of patients with dermatomyositis (DM). METHODS The study group consisted of 11 patients, including 3 children, all of whom had a clinical diagnosis of DM. A control group of 8 subjects was studied simultaneously. MRI included images as well as calculations of T1 and T2 relaxation times. The P-31 MRS protocol evaluated metabolic status (i.e., inorganic phosphate/phosphocreatine ratios and phosphocreatine and ATP levels) during rest, exercise, and recovery. RESULTS T2-weighted images of the thigh muscles showed inflammation even when serum creatine phosphokinase levels were in the normal range. Metabolic abnormalities, which were accentuated with exercise, were found in 10 patients. In some individuals, bioenergetic defects preceded other changes and persisted after resolution of inflammation. In general, clinical impressions correlated with MRI/MRS data. CONCLUSION MRI and MRS provide unique data which are quantitative and which cannot be obtained from routine laboratory tests. These MR evaluations appear to be of value in assessing the status of DM patients during treatment with steroids and immunosuppressive drugs.
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Affiliation(s)
- J H Park
- Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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29
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Nuutila P, Knuuti MJ, Heinonen OJ, Ruotsalainen U, Teräs M, Bergman J, Solin O, Yki-Järvinen H, Voipio-Pulkki LM, Wegelius U. Different alterations in the insulin-stimulated glucose uptake in the athlete's heart and skeletal muscle. J Clin Invest 1994; 93:2267-74. [PMID: 8182160 PMCID: PMC294384 DOI: 10.1172/jci117226] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Physical training increases skeletal muscle insulin sensitivity. Since training also causes functional and structural changes in the myocardium, we compared glucose uptake rates in the heart and skeletal muscles of trained and untrained individuals. Seven male endurance athletes (VO2max 72 +/- 2 ml/kg/min) and seven sedentary subjects matched for characteristics other than VO2max (43 +/- 2 ml/kg/min) were studied. Whole body glucose uptake was determined with a 2-h euglycemic hyperinsulinemic clamp, and regional glucose uptake in femoral and arm muscles, and myocardium using 18F-fluoro-2-deoxy-D-glucose and positron emission tomography. Glucose uptake in the athletes was increased by 68% in whole body (P < 0.0001), by 99% in the femoral muscles (P < 0.01), and by 62% in arm muscles (P = 0.06), but it was decreased by 33% in the heart muscle (P < 0.05) as compared with the sedentary subjects. The total glucose uptake rate in the heart was similar in the athletes and control subjects. Left ventricular mass in the athletes was 79% greater (P < 0.001) and the meridional wall stress smaller (P < 0.001) as estimated by echocardiography. VO2max correlated directly with left ventricular mass (r = 0.87, P < 0.001) and inversely with left ventricular wall stress (r = -0.86, P < 0.001). Myocardial glucose uptake correlated directly with the rate-pressure product (r = 0.75, P < 0.02) and inversely with left ventricular mass (r = -0.60, P < 0.05) or with the whole body glucose disposal (r = -0.68, P < 0.01). Thus, in athletes, (a) insulin-stimulated glucose uptake is enhanced in the whole body and skeletal muscles, (b) whereas myocardial glucose uptake per muscle mass is reduced possibly due to decreased wall stress and energy requirements or the use of alternative fuels, or both.
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Affiliation(s)
- P Nuutila
- Department of Medicine, University of Turku, Finland
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30
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King LE, Park JH, Adams L, Vital T, Olsen NJ. Evaluation of muscles in a patient with suspected amyopathic dermatomyositis by magnetic resonance imaging and phosphorus-31-spectroscopy. J Am Acad Dermatol 1994; 30:137-8. [PMID: 8277018 DOI: 10.1016/s0190-9622(08)81904-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- L E King
- Department of Medicine (Dermatology), Vanderbilt University, Nashville, TN
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31
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Iotti S, Lodi R, Frassineti C, Zaniol P, Barbiroli B. In vivo assessment of mitochondrial functionality in human gastrocnemius muscle by 31P MRS. The role of pH in the evaluation of phosphocreatine and inorganic phosphate recoveries from exercise. NMR IN BIOMEDICINE 1993; 6:248-253. [PMID: 8217526 DOI: 10.1002/nbm.1940060404] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In this study we compared the kinetics of phosphocreatine (PCr) and P(i) recovery, and their dependency on cytosolic pH in 38 normal individuals. Spectra were acquired during rest, work and recovery. A time resolution of 10 s was used to obtain detailed information. The kinetics of PCr and P(i) recovery almost overlapped when the lowest value of cytosolic pH reached during recovery (termed the minimum pH) was < 6.95, while they were completely dissociated when the minimum pH was > 6.95. This result is interpreted as indirect in vivo evidence of the kinetic control exerted by ADP on mitochondrial oxidation. Our results represent a rationale for new experimental conditions to be used in clinical routine studies of pathologies due to primary or secondary mitochondrial malfunction.
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Affiliation(s)
- S Iotti
- Istituto di Patologia Medica D. Campanacci, Università di Bologna, Italy
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32
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Barnes PR, Taylor DJ, Kemp GJ, Radda GK. Skeletal muscle bioenergetics in the chronic fatigue syndrome. J Neurol Neurosurg Psychiatry 1993; 56:679-83. [PMID: 8509783 PMCID: PMC489619 DOI: 10.1136/jnnp.56.6.679] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Skeletal muscle bioenergetics and control of intracellular pH have been investigated in 46 patients with chronic fatigue syndrome by phosphorus magnetic resonance spectroscopy. The results have been compared with those from healthy controls and from a group of patients with mitochondrial cytopathies affecting skeletal muscle. No consistent abnormalities of glycolysis, mitochondrial metabolism or pH regulation were identified in the group when taken as a whole, although in 12 of the 46 patients the relationship between pH and phosphocreatine utilisation during exercise fell outside the normal range. Of these, 6 patients showed increased acidification relative to phosphocreatine depletion while 6 showed reduced acidification. These findings do not support the hypothesis that any specific metabolic abnormality underlies fatigue in this syndrome although abnormalities may be present in a minority of patients.
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Affiliation(s)
- P R Barnes
- MRC Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, UK
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33
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Funicello R, Barbiroli B, Zaniol P, Martinelli P. Energy metabolism in muscle paresis and recovery studied by 31P-MR spectroscopy: a case report. ITALIAN JOURNAL OF NEUROLOGICAL SCIENCES 1993; 14:263-7. [PMID: 8314681 DOI: 10.1007/bf02335669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We report a 31P Magnetic Resonance Spectroscopy (31P-MRS) study on the changes of energy metabolism in human leg anterior and lateral compartment muscles with paresis due to compression from a herniated lumbar disc at the L4-L5 level and recovery to normality. A low phosphocreatine to inorganic phosphate ratio due to both decreased phosphocreatine and increased inorganic phosphate contents and a normal intracellular pH were the features of muscles with paresis. Changes of 31P-MRS parameters were followed during 18 weeks of treatment with physical therapy until complete recovery. Results show that 31P-MRS is a useful clinical tool for detecting even small biochemical changes that may occur in muscles and for checking the effects of therapy.
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Affiliation(s)
- R Funicello
- Cattedra di Biochimica Clinica, Università di Bologna
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34
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González de Suso JM, Bernús G, Alonso J, Alay A, Capdevila A, Gili J, Prat JA, Arús C. Development and characterization of an ergometer to study the bioenergetics of the human quadriceps muscle by 31P NMR spectroscopy inside a standard MR scanner. Magn Reson Med 1993; 29:575-81. [PMID: 8464378 DOI: 10.1002/mrm.1910290425] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A description is given of an ergometer made of nonmagnetic materials which fits into a standard whole body MR magnet. T2-weighted images show that exercise is highly specific for quadriceps muscles. The ergometer permits the noninvasive study of T2-related changes in the proton images of the leg as well as changes occurring in muscle bioenergetics during exercise and recovery.
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35
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Vandenborne K, McCully K, Kakihira H, Prammer M, Bolinger L, Detre JA, De Meirlier K, Walter G, Chance B, Leigh JS. Metabolic heterogeneity in human calf muscle during maximal exercise. Proc Natl Acad Sci U S A 1991; 88:5714-8. [PMID: 2062850 PMCID: PMC51948 DOI: 10.1073/pnas.88.13.5714] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Human skeletal muscle is composed of various muscle fiber types. We hypothesized that differences in metabolism between fiber types could be detected noninvasively with 31P nuclear magnetic resonance spectroscopy during maximal exercise. This assumes that during maximal exercise all fiber types are recruited and all vary in the amount of acidosis. The calf muscles of seven subjects were studied. Two different coils were applied: an 11-cm-diameter surface coil and a five-segment meander coil. The meander coil was used to localize the 31P signal to either the medial or the lateral gastrocnemius. Maximal exercise, consisting of rapid plantar flexions, resulted in an 83.7% +/- 7.8% decrease of the phosphocreatine pool and an 8-fold increase of the inorganic phosphate (Pi) pool. At rest the Pi pool was observed as a single resonance (pH 7.0). Toward the end of the first minute of exercise, three subjects showed three distinct Pi peaks. During the second minute of exercise the pH values stabilized at 7.12 +/- 0.12, 6.63 +/- 0.15, and 6.27 +/- 0.23. The same pattern was seen when the signal was collected from the medial or lateral gastrocnemius. In four subjects only two distinct Pi peaks were observed. The Pi peaks had differing relative areas in different subjects, but they were reproducible in each individual. This method allowed us to study the appearance and disappearance of the different Pi peaks, together with the changes in pH. Because multiple Pi peaks were seen in single muscles they most likely identify different muscle fiber types.
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Affiliation(s)
- K Vandenborne
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104
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36
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Ball-Burnett M, Green HJ, Houston ME. Energy metabolism in human slow and fast twitch fibres during prolonged cycle exercise. J Physiol 1991; 437:257-67. [PMID: 1890634 PMCID: PMC1180046 DOI: 10.1113/jphysiol.1991.sp018594] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. The effects of prolonged exercise on energy metabolism in type I and type II muscle fibres in the vastus lateralis muscle were investigated in six male subjects (20.0 +/- 0.5 years, mean +/- S.E.M.) who performed one-legged cycling at 61% of maximum O2 consumption (VO2,max; determined with one leg) until fatigue or for a maximum of 2 h. 2. Analysis of pools of freeze-dried fibres obtained by needle biopsy and separated into specific types by the myofibrillar ATPase histochemical procedure indicated higher (P less than 0.05) lactate concentrations in type II fibres compared to type I fibres at 15 min (43.9 +/- 9.7 and 51.2 +/- 9.8 mmol (kg dry wt)-1) and at 60 min (18.2 +/- 4.7 and 25.9 +/- 6.5 mmol (kg dry wt)-1). No differences existed in lactate concentration between fibre types for pre-exercise (10.0 +/- 1.6 and 13.3 +/- 2.8 mmol (kg dry wt)-1) or post-exercise. 3. Glycogen degradation was most pronounced in type I fibres. By the end of exercise, glycogen concentration was 82.4 +/- 45 mmol glucosyl units (kg dry wt)-1 in type I fibres and 175 +/- 62 mmol glucosyl units (kg dry wt)-1 in type II fibres. 4. No significant changes in ATP and creatine phosphate (CrP) were found in either fibre type with exercise. 5. It is concluded that, at least for lactate and glycogen, fibre-specific differences are evident in prolonged submaximal exercise. The cause of the difference probably relates both to the unique energy metabolic characteristics of each fibre type and to the manner in which they are utilized during the exercise. 6. The failure to find a reduction in ATP concentration in either fibre type during prolonged exercise in the face of a progressive increase in the number of fibres showing little or no glycogen concentration suggests that protective mechanisms exist that prevent an energy crisis. The nature of these protective mechanisms remains to be elucidated.
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Affiliation(s)
- M Ball-Burnett
- Department of Kinesiology, University of Waterloo, Ontario, Canada
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37
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Harris RC, Marlin DJ, Snow DH, Harkness RA. Muscle ATP loss and lactate accumulation at different work intensities in the exercising Thoroughbred horse. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1991; 62:235-44. [PMID: 2044532 DOI: 10.1007/bf00571546] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of 2 min treadmill exercise, at speeds of 6-12 m.s-1 on an incline of 5 degrees, upon muscle adenine nucleotide loss and lactate accumulation was studied in six Thoroughbred horses. Minimal change occurred in the adenosine triphosphate (ATP) content of the middle gluteal muscle at speeds of 10 m.s-1 or less, but significant loss (up to 47%) had occurred in all horses by 12 m.s-1. The decline in ATP significantly correlated with the accumulation of muscle lactate, beginning shortly after the accumulation of 40 mmol.kg-1 dry muscle lactate. Decline in muscle ATP was mirrored closely by the appearance of ammonia, and to a lesser extent, hypoxanthine and uric acid in plasma. The results suggest that peak accumulation of any of these, or simply the concentration at a specified recovery time, may be used as a measure of ATP loss in the musculature as a whole. This was not so in the case of xanthine, which may also be formed from the degradation of guanidine nucleotides. An In-In plot of plasma ammonia against treadmill speed indicated a break point in accumulation between 8 and 9 m.s-1. The kinetics of ammonia accumulation with speed differed from those of lactate.
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Affiliation(s)
- R C Harris
- Department of Comparative Physiology, Animal Health Trust, Newmarket, England
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38
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Bendahan D, Confort-Gouny S, Kozak-Reiss G, Cozzone PJ. Heterogeneity of metabolic response to muscular exercise in humans. New criteria of invariance defined by in vivo phosphorus-31 NMR spectroscopy. FEBS Lett 1990; 272:155-8. [PMID: 2226826 DOI: 10.1016/0014-5793(90)80472-u] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
31P NMR spectroscopy at 4.7 T has been used in vivo to follow metabolic changes associated with exercise and subsequent recovery in the forearm flexor digitorum superficialis muscle of 14 healthy volunteers. The muscle content in phosphomonoesters at rest provides an index of glycogenolytic activity. Quantitative linear correlations have been shown to link end-of-exercise acidosis to recovery kinetics of phosphocreatine and phosphocreatine/organic phosphate ratio. These linear relationships constitute new metabolic invariants to be used in the study of myopathies and muscle adaptation to exercise.
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Affiliation(s)
- D Bendahan
- Centre de Résonance Magnétique Biologique et Médicale, Faculté de Médecine de Marseille, France
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