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Tam E, Nardon M, Bertucco M, Capelli C. The mechanisms underpinning the slow component of [Formula: see text] in humans. Eur J Appl Physiol 2024; 124:861-872. [PMID: 37775591 DOI: 10.1007/s00421-023-05315-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 09/01/2023] [Indexed: 10/01/2023]
Abstract
PURPOSE When exercising above the lactic threshold (LT), the slow component of oxygen uptake ([Formula: see text]) appears, mainly ascribed to the progressive recruitment of Type II fibers. However, also the progressive decay of the economy of contraction may contribute to it. We investigated oxygen uptake ([Formula: see text]) during isometric contractions clamping torque (T) or muscular activation to quantify the contributions of the two mechanisms. METHODS We assessed for 7 min T of the leg extensors, net oxygen uptake ([Formula: see text]) and root mean square (RMS) from vastus lateralis (VL) in 11 volunteers (21 ± 2 yy; 1.73 ± 0.11 m; 67 ± 14 kg) during cyclic isometric contractions (contraction/relaxation 5 s/5 s): (i) at 65% of maximal voluntary contraction (MVC) (FB-Torque) and; (ii) keeping the level of RMS equal to that at 65% of MVC (FB-EMG). RESULTS [Formula: see text] after the third minute in FB-Torque increased with time ([Formula: see text] = 94 × t + 564; R2 = 0.99; P = 0.001), but not during FB-EMG. [Formula: see text]/T increased only during FB-Torque ([Formula: see text]/T = 1.10 × t + 0.57; R2 = 0.99; P = 0.001). RMS was larger in FB-Torque than in FB-EMG and significantly increased in the first three minutes of exercise to stabilize till the end of the trial, indicating that the pool of recruited MUs remained constant despite [Formula: see text]. CONCLUSION The analysis of the RMS, [Formula: see text] and T during FB-Torque suggests that the intrinsic mechanism attributable to the decay of contraction efficiency was responsible for an increase of [Formula: see text] equal to 18% of the total [Formula: see text].
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Affiliation(s)
- Enrico Tam
- Section of Movement Sciences, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, 37131, Verona, Italy.
| | - Mauro Nardon
- Section of Movement Sciences, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, 37131, Verona, Italy
| | - Matteo Bertucco
- Section of Movement Sciences, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, 37131, Verona, Italy
| | - Carlo Capelli
- Section of Movement Sciences, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, 37131, Verona, Italy
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Nascimento EMF, Klitzke Borszcz F, Ventura TP, Caputo F, Guglielmo LGA, de Lucas RD. Reliability and Validity of Cycling Sprint Performance at Isolinear Mode Without Torque Factor: A Preliminary Study in Well-Trained Male Cyclists. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2024:1-8. [PMID: 38319597 DOI: 10.1080/02701367.2023.2298752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/19/2023] [Indexed: 02/07/2024]
Abstract
Purpose: This study aimed to compare the performance-derived parameters utilizing isolinear (ISOLIN) and isovelocity (ISOVEL) sprint cycling modes. Method: For that, 20 male trained cyclists performed 2 sprints of 7 s on an electromagnetically braked cycle ergometer in ISOLIN and six sprints in ISOVEL mode with cadences between 90 and 180 rpm, each separated by 3-min. A linear function modeled the sprints within each mode to extrapolate maximal cadence (CMAX) and torque (TMAX), and a quadratic function was used to extrapolate the apex defined as optimal cadence power (OPTCAD) and peak power output (PMAX). Fifteen subjects performed another 4 sprints at ISOLIN mode on different days to verify the reliability. Results: The measures from the power-cadence relationship were not different between the ISOLIN and ISOVEL modes. Although significant differences were detected in the T-C relationship, TMAX was greater at ISOLIN than ISOVEL (p = .006). On the other hand, CMAX was higher at ISOVEL than ISOLIN (p < .001). The correlation between parameters was large to very large (r = 0.51 to 0.89). However, high limits of agreement were verified. The ISOLIN presented consistency during the trials, and the random errors were acceptable (CV = 5.3% to 11.5%). Conclusion: Using the power-cadence relationship, PMAX and OPTCAD could be detected similarly between the two sprint modes (ISOLIN and ISOVEL). Thus, the findings demonstrated that a single ISOLIN sprint test could be a suitable tool for quantifying the time course of muscle fatigue during and after cycling exercises in well-trained male cyclists.
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Flensted-Jensen M, Kleis-Olsen AS, Hassø RK, Lindtofte S, Corral Pérez J, Ortega-Gómez S, Larsen S. Combined changes in temperature and pH mimicking exercise result in decreased efficiency in muscle mitochondria. J Appl Physiol (1985) 2024; 136:79-88. [PMID: 37969081 DOI: 10.1152/japplphysiol.00293.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/17/2023] Open
Abstract
It is well known that exercise efficiency declines at intensities above the lactate threshold, yet the underlying mechanisms are poorly understood. Some have suggested it is due to a decline in mitochondrial efficiency, but this is difficult to examine in vivo. Therefore, the aim of the current study was to examine how changes in temperature and pH, mimicking those that occur during exercise, affect mitochondrial efficiency in skeletal muscle mitochondria. This study was performed on quadriceps muscle of 20 wild-type mice. Muscle tissue was dissected and either permeabilized (n = 10) or homogenized for isolation of mitochondria (n = 10), and oxidative phosphorylation capacity and P/O ratio were assessed using high-resolution respirometry. Samples from each muscle were analyzed in both normal physiological conditions (37°C, pH 7.4), decreased pH (6.8), increased temperature (40°C), and a combination of both. The combination of increased temperature and decreased pH resulted in a significantly lower P/O ratio, mirrored by an increase in leak respiration and a decrease in respiratory control ratio (RCR), in isolated mitochondria. In permeabilized fibers, RCR and leak were relatively unaffected, though a main effect of temperature was observed. Oxidative phosphorylation capacity was unaffected by changes in pH and temperature in both isolated mitochondria and permeabilized fibers. These results indicate that exercise-like changes in temperature and pH lead to impaired mitochondrial efficiency. These findings offer some degree of support to the concept of decreased mitochondrial efficiency during exercise, and may have implications for the assessment of mitochondrial function related to exercise.NEW & NOTEWORTHY To the best of our knowledge, this is the first study to examine the effects of combined changes in temperature and pH, mimicking intramuscular alterations during exercise. Our findings suggest that mitochondrial efficiency is impaired during exercise of moderate to high intensity, which could be a possible mechanism contributing to the decline in exercise efficiency at intensities above the lactate threshold.
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Affiliation(s)
- Mathias Flensted-Jensen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ann-Sofie Kleis-Olsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Kinimond Hassø
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Lindtofte
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Juan Corral Pérez
- MOVE-IT Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain
- ExPhy Research Group, Department of Physical Education, Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Universidad de Cádiz, Cádiz, Spain
| | - Sonia Ortega-Gómez
- MOVE-IT Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain
- Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital, Cádiz, Spain
| | - Steen Larsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland
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4
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Sietsema KE, Rossiter HB. Exercise Physiology and Cardiopulmonary Exercise Testing. Semin Respir Crit Care Med 2023; 44:661-680. [PMID: 37429332 DOI: 10.1055/s-0043-1770362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Aerobic, or endurance, exercise is an energy requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis. The consumption of oxygen and production of carbon dioxide in muscle cells are dynamically linked to oxygen uptake (V̇O2) and carbon dioxide output (V̇CO2) at the lung by integrated functions of cardiovascular, pulmonary, hematologic, and neurohumoral systems. Maximum oxygen uptake (V̇O2max) is the standard expression of aerobic capacity and a predictor of outcomes in diverse populations. While commonly limited in young fit individuals by the capacity to deliver oxygen to exercising muscle, (V̇O2max) may become limited by impairment within any of the multiple systems supporting cellular or atmospheric gas exchange. In the range of available power outputs, endurance exercise can be partitioned into different intensity domains representing distinct metabolic profiles and tolerances for sustained activity. Estimates of both V̇O2max and the lactate threshold, which marks the upper limit of moderate-intensity exercise, can be determined from measures of gas exchange from respired breath during whole-body exercise. Cardiopulmonary exercise testing (CPET) includes measurement of V̇O2 and V̇CO2 along with heart rate and other variables reflecting cardiac and pulmonary responses to exercise. Clinical CPET is conducted for persons with known medical conditions to quantify impairment, contribute to prognostic assessments, and help discriminate among proximal causes of symptoms or limitations for an individual. CPET is also conducted in persons without known disease as part of the diagnostic evaluation of unexplained symptoms. Although CPET quantifies a limited sample of the complex functions and interactions underlying exercise performance, both its specific and global findings are uniquely valuable. Some specific findings can aid in individualized diagnosis and treatment decisions. At the same time, CPET provides a holistic summary of an individual's exercise function, including effects not only of the primary diagnosis, but also of secondary and coexisting conditions.
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Affiliation(s)
- Kathy E Sietsema
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, California
| | - Harry B Rossiter
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, California
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Reinpõld K, Rannama I. Oxygen Uptake and Bilaterally Measured Vastus Lateralis Muscle Oxygen Desaturation Kinetics in Well-Trained Endurance Cyclists. J Funct Morphol Kinesiol 2023; 8:jfmk8020064. [PMID: 37218860 DOI: 10.3390/jfmk8020064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023] Open
Abstract
The aim of the present study was to compare and analyse the relationships between pulmonary oxygen uptake and vastus lateralis (VL) muscle oxygen desaturation kinetics measured bilaterally with Moxy NIRS sensors in trained endurance athletes. To this end, 18 trained athletes (age: 42.4 ± 7.2 years, height: 1.837 ± 0.053 m, body mass: 82.4 ± 5.7 kg) visited the laboratory on two consecutive days. On the first day, an incremental test was performed to determine the power values for the gas exchange threshold, the ventilatory threshold (VT), and V̇O2max levels from pulmonary ventilation. On the second day, the athletes performed a constant work rate (CWR) test at the power corresponding to the VT. During the CWR test, the pulmonary ventilation characteristics, left and right VL muscle O2 desaturation (DeSmO2), and pedalling power were continuously recorded, and the average signal of both legs' DeSmO2 was computed. Statistical significance was set at p ≤ 0.05. The relative response amplitudes of the primary and slow components of VL desaturation and pulmonary oxygen uptake kinetics did not differ, and the primary amplitude of muscle desaturation kinetics was strongly associated with the initial response rate of oxygen uptake. Compared with pulmonary O2 kinetics, the primary response time of the muscle desaturation kinetics was shorter, and the slow component started earlier. There was good agreement between the time delays of the slow components describing global and local metabolic processes. Nevertheless, there was a low level of agreement between contralateral desaturation kinetic variables. The averaged DeSmO2 signal of the two sides of the body represented the oxygen kinetics more precisely than the right- or left-leg signals separately.
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Affiliation(s)
- Karmen Reinpõld
- School of Natural Sciences and Health, University of Tallinn, 10120 Tallinn, Estonia
| | - Indrek Rannama
- School of Natural Sciences and Health, University of Tallinn, 10120 Tallinn, Estonia
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6
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Goulding RP, Burnley M, Wüst RCI. How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance. Sports Med 2023; 53:959-976. [PMID: 37010782 PMCID: PMC10115720 DOI: 10.1007/s40279-023-01832-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/04/2023]
Abstract
The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ([Formula: see text]O2) kinetics, termed the "priming effect", has garnered significant research attention and its underpinning mechanisms have been hotly debated. In the first part of this review, the evidence for and against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns and (5) enhanced intracellular O2 utilisation in underpinning the priming effect is discussed. Lactic acidosis and increased muscle temperature are most likely not key determinants of the priming effect. Whilst priming increases muscle O2 delivery, many studies have demonstrated that an increased muscle O2 delivery is not a prerequisite for the priming effect. Motor unit recruitment patterns are altered by prior exercise, and these alterations are consistent with some of the observed changes in [Formula: see text]O2 kinetics in humans. Enhancements in intracellular O2 utilisation likely play a central role in mediating the priming effect, probably related to elevated mitochondrial calcium levels and parallel activation of mitochondrial enzymes at the onset of the second bout. In the latter portion of the review, the implications of priming on the parameters of the power-duration relationship are discussed. The effect of priming on subsequent endurance performance depends critically upon which phases of the [Formula: see text]O2 response are altered. A reduced [Formula: see text]O2 slow component or increased fundamental phase amplitude tend to increase the work performable above critical power (i.e. W´), whereas a reduction in the fundamental phase time constant following priming results in an increased critical power.
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Affiliation(s)
- Richie P Goulding
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
| | - Mark Burnley
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Rob C I Wüst
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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7
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do Nascimento Salvador PC, Nascimento EMF, Antunes D, Guglielmo LGA, Denadai BS. Energy metabolism and muscle activation heterogeneity explain V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component and muscle fatigue of cycling at different intensities. Exp Physiol 2023; 108:503-517. [PMID: 36648072 PMCID: PMC10103881 DOI: 10.1113/ep090444] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 12/13/2022] [Indexed: 01/18/2023]
Abstract
NEW FINDINGS What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O2 cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, theV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue andV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes. ABSTRACT This study aimed to explain theV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3 s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath-by-breathV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ , near-infrared spectroscopy signals and EMG activity were analysed (thigh muscles).V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ was higher during VHI exercise (∼70% vs. ∼28% ofV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2 min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship betweenV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ and muscle force production was observed. The τ of muscleV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ was significantly related (R2 = 0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R2 = 0.30 and 0.31, respectively) and theV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ (R2 = 0.39 and 0.27, respectively). TheV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ is also partially explained by blood lactate accumulation (R2 = 0.42). In conclusion muscle fatigue and O2 cost seem to share the same physiological cause linked with a decrease in the muscleV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ and a change in lactate accumulation. Muscle fatigue andV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.
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Affiliation(s)
- Paulo Cesar do Nascimento Salvador
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
- Leonardo da Vinci University – Uniasselvi/VITRU EducationIndaialBrazil
| | | | - Diego Antunes
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
| | | | - Benedito Sérgio Denadai
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
- Human Performance LaboratorySão Paulo State UniversityRio ClaroBrazil
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8
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Interaction of Factors Determining Critical Power. Sports Med 2023; 53:595-613. [PMID: 36622556 PMCID: PMC9935749 DOI: 10.1007/s40279-022-01805-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 01/10/2023]
Abstract
The physiological determinants of high-intensity exercise tolerance are important for both elite human performance and morbidity, mortality and disease in clinical settings. The asymptote of the hyperbolic relation between external power and time to task failure, critical power, represents the threshold intensity above which systemic and intramuscular metabolic homeostasis can no longer be maintained. After ~ 60 years of research into the phenomenon of critical power, a clear understanding of its physiological determinants has emerged. The purpose of the present review is to critically examine this contemporary evidence in order to explain the physiological underpinnings of critical power. Evidence demonstrating that alterations in convective and diffusive oxygen delivery can impact upon critical power is first addressed. Subsequently, evidence is considered that shows that rates of muscle oxygen utilisation, inferred via the kinetics of pulmonary oxygen consumption, can influence critical power. The data reveal a clear picture that alterations in the rates of flux along every step of the oxygen transport and utilisation pathways influence critical power. It is also clear that critical power is influenced by motor unit recruitment patterns. On this basis, it is proposed that convective and diffusive oxygen delivery act in concert with muscle oxygen utilisation rates to determine the intracellular metabolic milieu and state of fatigue within the myocytes. This interacts with exercising muscle mass and motor unit recruitment patterns to ultimately determine critical power.
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9
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Poole DC, Koga S. 'Fatigue makes cowards of us all'. Exp Physiol 2023; 108:336-337. [PMID: 36744657 PMCID: PMC10988486 DOI: 10.1113/ep091111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 01/18/2023] [Indexed: 02/07/2023]
Affiliation(s)
- David C. Poole
- Department of KinesiologyKansas State UniversityManhattanKansasUSA
- Department Anatomy & PhysiologyKansas State UniversityManhattanKansasUSA
| | - Shunsaku Koga
- Applied Physiology LaboratoryKobe Design UniversityNishi‐kuKobeJapan
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10
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ARIMITSU T, YAMANAKA R, YUNOKI T, YANO T. Effects of exercise-induced muscle fatigue on V̇O2 slow component during heavy constant load exercise. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2022. [DOI: 10.23736/s0393-3660.20.04469-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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MacDougall KB, Falconer TM, MacIntosh BR. Efficiency of cycling exercise: Quantification, mechanisms, and misunderstandings. Scand J Med Sci Sports 2022; 32:951-970. [PMID: 35253274 DOI: 10.1111/sms.14149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/19/2022] [Accepted: 02/09/2022] [Indexed: 12/24/2022]
Abstract
The energetics of cycling represents a well-studied area of exercise science, yet there are still many questions that remain. Efficiency, broadly defined as the ratio of energy output to energy input, is one key metric that, despite its importance from both a scientific as well as performance perspective, is commonly misunderstood. There are many factors that may affect cycling efficiency, both intrinsic (e.g., muscle fiber type composition) and extrinsic (e.g., cycling cadence, prior exercise, and training), creating a complex interplay of many components. Due to its relative simplicity, the measurement of oxygen uptake continues to be the most common means of measuring the energy cost of exercise (and thus efficiency); however, it is limited to only a small proportion of the range of outputs humans are capable of, further limiting our understanding of the energetics of high-intensity exercise and any mechanistic bases therein. This review presents evidence that delta efficiency does not represent muscular efficiency and challenges the notion that the slow component of oxygen uptake represents decreasing efficiency. It is noted that gross efficiency increases as intensity of exercise increases in spite of the fact that fast-twitch fibers are recruited to achieve this high power output. Understanding the energetics of high-intensity exercise will require critical evaluation of the available data.
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Affiliation(s)
- Keenan B MacDougall
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Tara M Falconer
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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12
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Gløersen Ø, Colosio AL, Boone J, Dysthe DK, Malthe-Sørenssen A, Capelli C, Pogliaghi S. Modeling VO 2 on-kinetics based on intensity-dependent Delayed Adjustment and Loss of Efficiency (DALE). J Appl Physiol (1985) 2022; 132:1480-1488. [PMID: 35482330 DOI: 10.1152/japplphysiol.00570.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study presents and evaluates a new mathematical model of V̇O2 on-kinetics, with the following properties: (i) a progressively slower primary phase following the size-principle of motor unit recruitment, explaining the delayed V̇O2 steady state seen in the heavy exercise intensity domain, and (ii) a severe-domain slow component modelled as a time-dependent decrease in efficiency. Breath-by-breath V̇O2 measurements from eight subjects performing step cycling transitions, in the moderate, heavy and severe exercise domains, were fitted to the conventional 3-phase model and the new model. Model performance was evaluated with a residual analysis and by comparing Bayesian (BIC) and corrected Akaike (AICc) information criteria. The residual analysis showed no systematic deviations, except perhaps for the initial part of the primary phase. BIC favored the new model, being 9.3 (SD 7.1) lower than the conventional model while AICc was similar between models. Compared to the conventional 3-phase model, the proposed model distinguishes between the kinetic adaptations in the heavy and severe domains by predicting a delayed steady state V̇O2 in the heavy and no steady state V̇O2 in the severe domain. This allows to determine when stable oxygen costs of exercise are attainable and it also represents a first step in defining time-dependent oxygen costs when stable energy conversion efficiency is not attainable.
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Affiliation(s)
- Øyvind Gløersen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Department of Physics, University of Oslo, Oslo, Norway.,Smart Sensors and Microsystems, SINTEF Digital, Oslo, Norway
| | - Alessandro L Colosio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | | | | | - Carlo Capelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Silvia Pogliaghi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Cao M, Calmelat RA, Kierstead P, Carraro N, Stringer WW, Porszasz J, Casaburi R, Rossiter HB. A randomized, crossover, placebo controlled, double blind trial of the effects of tiotropium-olodaterol on neuromuscular performance during exercise in COPD. J Appl Physiol (1985) 2022; 132:1145-1153. [PMID: 35323052 PMCID: PMC9054255 DOI: 10.1152/japplphysiol.00332.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise intolerance in COPD is associated with dyspnea, reduced inspiratory capacity (IC) and occurs with a neuromuscular "power reserve" i.e. an acute ability to increase isokinetic locomotor power. This power reserve is associated with resting FEV1/FVC suggesting that treatments to target pulmonary function may protect neuromuscular performance and extend whole-body exercise in COPD. We, therefore, tested whether combination long-acting β-agonist and muscarinic antagonist bronchodilator therapy (LAMA+LABA; Stiolto Respimat®) would ameliorate the decline in neuromuscular performance and increase endurance time during constant power cycling at 80% peak incremental power. Fourteen COPD patients (4 female; 64[58,72] years; FEV1 67[56,75]% predicted; median[25th,75th percentile]), participated in a randomized, placebo-controlled cross-over trial (NCT02845752). Pulmonary function and cardiopulmonary exercise responses were assessed before and after 1 week of treatment, with 2 weeks washout between conditions. Performance fatigue was assessed using a ~4-second maximal isokinetic cycling effort at pre-exercise, isotime and intolerance. Isotime was the shorter exercise duration of the two treatment conditions. Significance was assessed using ANOVA with treatment as fixed factor and subject as random factor. FEV1 was greater with LAMA+LABA vs. placebo (1.81[1.58,1.98] L vs 1.72[1.29,1.99] L; P=0.006), but IC at isotime, performance fatigue at isotime and constant power endurance time were not different between condition (each P>0.05). A modest (~95 mL) FEV1 increase in following 1 week of combination LAMA+LABA treatment did not alleviate neuromuscular performance fatigue or enhance cycle exercise tolerance in mild to severe COPD patients with largely preserved "static" lung volumes.
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Affiliation(s)
- Min Cao
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States.,Department of Respiratory and Critical Care Medicine, Beijing Chest Hospital, Capital Medical University, Beijing, China
| | - Robert A Calmelat
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Peter Kierstead
- Antioch Medical Center, Pulmonary Medicine, Antioch, CA, United States
| | - Nicolo Carraro
- High Specialization Rehabilitation Hospital, ORAS, Motta di Livenza, Italy
| | - William W Stringer
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Janos Porszasz
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Richard Casaburi
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
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Elshafei M, Costa DE, Shihab E. Toward the Personalization of Biceps Fatigue Detection Model for Gym Activity: An Approach to Utilize Wearables' Data from the Crowd. SENSORS (BASEL, SWITZERLAND) 2022; 22:1454. [PMID: 35214356 PMCID: PMC8877759 DOI: 10.3390/s22041454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/05/2022] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Nowadays, wearables-based Human Activity Recognition (HAR) systems represent a modern, robust, and lightweight solution to monitor athlete performance. However, user data variability is a problem that may hinder the performance of HAR systems, especially the cross-subject HAR models. Such a problem may have a lesser effect on the subject-specific model because it is a tailored model that serves a specific user; hence, data variability is usually low, and performance is often high. However, such a performance comes with a high cost in data collection and processing per user. Therefore, in this work, we present a personalized model that achieves higher performance than the cross-subject model while maintaining a lower data cost than the subject-specific model. Our personalization approach sources data from the crowd based on similarity scores computed between the test subject and the individuals in the crowd. Our dataset consists of 3750 concentration curl repetitions from 25 volunteers with ages and BMI ranging between 20-46 and 24-46, respectively. We compute 11 hand-crafted features and train 2 personalized AdaBoost models, Decision Tree (AdaBoost-DT) and Artificial Neural Networks (AdaBoost-ANN), using data from whom the test subject shares similar physical and single traits. Our findings show that the AdaBoost-DT model outperforms the cross-subject-DT model by 5.89%, while the AdaBoost-ANN model outperforms the cross-subject-ANN model by 3.38%. On the other hand, at 50.0% less of the test subject's data consumption, our AdaBoost-DT model outperforms the subject-specific-DT model by 16%, while the AdaBoost-ANN model outperforms the subject-specific-ANN model by 10.33%. Yet, the subject-specific models achieve the best performances at 100% of the test subjects' data consumption.
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15
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Almeida Azevedo R, Keir DA, Forot J, Iannetta D, Millet GY, Murias JM. The effects of exercise intensity and duration on the relationship between the slow component of V̇O 2 and peripheral fatigue. Acta Physiol (Oxf) 2022; 234:e13776. [PMID: 34985184 DOI: 10.1111/apha.13776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/15/2021] [Accepted: 01/01/2022] [Indexed: 11/30/2022]
Abstract
AIM If the development of the oxygen uptake slow component (V̇O2SC ) and muscle fatigue are related, these variables should remain coupled in a time- and intensity-dependent manner. METHODS 16 participants (7 females) visited the laboratory on 7 separate occasions: (1) three 6-minutes moderate-intensity cycling exercise bouts proceeded by a ramp incremental test; (2-3) 30-minutes constant power output (PO) exercise bout to determine the maximal lactate steady state (MLSS); (4-7) constant-PO exercise bouts to task failure (TTF), pseudorandomized order, at (i) 15% below the PO at MLSS; (ii) 10 W below MLSS; (iii) MLSS; (iv) 10 W above MLSS (first intensity and randomized order thereafter). Neuromuscular fatigue was characterized by isometric maximal voluntary contractions and femoral nerve electrical stimulation of knee extensors to measure peripheral fatigue at baseline, at min 5, 10, 20, 30 and TTF. Pulmonary oxygen uptake (V̇O2 ) was continuously recorded during the constant-PO bouts and V̇O2SC was characterized based on each individual V̇O2 kinetics during moderate transitions. RESULTS The development of V̇O2SC and peripheral fatigue were correlated across time (r2 adj range of 0.64-0.80) and amongst each exercise intensity (r2 adj range of 0.26-0.30) (all P < .001). Also, TTF was correlated with V̇O2SC and neuromuscular fatigue parameters (r2 adj range of 0.52-0.82, all P < .001). CONCLUSION The V̇O2SC and peripheral fatigue development are correlated throughout the exercise in a time- and intensity-dependent manner, suggesting that the V̇O2SC may depend on muscle fatigue even if the mechanisms of reduced contractile function are different amongst intensities.
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Affiliation(s)
| | - Daniel A. Keir
- School of Kinesiology The University of Western Ontario London Ontario Canada
- Department of Medicine Toronto General Hospital Research Institute University Health Network Toronto Ontario Canada
| | - Jonas Forot
- Faculty of Kinesiology University of Calgary Calgary Alberta Canada
- The Sport Performance Reserch Group National Ski‐Nordic Center Premanon France
| | - Danilo Iannetta
- Faculty of Kinesiology University of Calgary Calgary Alberta Canada
| | - Guillaume Y. Millet
- Faculty of Kinesiology University of Calgary Calgary Alberta Canada
- Inter‐University Laboratory of Human Movement Biology UJM‐Saint‐Etienne Univ Lyon Saint‐Etienne France
- Institut Universitaire de France (IUF) Paris France
| | - Juan M. Murias
- Faculty of Kinesiology University of Calgary Calgary Alberta Canada
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16
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Goulding RP, Rossiter HB, Marwood S, Ferguson C. Bioenergetic Mechanisms Linking V˙O2 Kinetics and Exercise Tolerance. Exerc Sport Sci Rev 2021; 49:274-283. [PMID: 34547760 PMCID: PMC8528340 DOI: 10.1249/jes.0000000000000267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We hypothesize that the V˙O2 time constant (τV˙O2) determines exercise tolerance by defining the power output associated with a "critical threshold" of intramuscular metabolite accumulation (e.g., inorganic phosphate), above which muscle fatigue and work inefficiency are apparent. Thereafter, the V˙O2 "slow component" and its consequences (increased pulmonary, circulatory, and neuromuscular demands) determine performance limits.
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Affiliation(s)
- Richie P. Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
- Laboratory for Myology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Harry B. Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance CA, 90254, USA
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, L16 9JD, UK
| | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, LS 2 9JT, UK
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17
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Bartlett MF, Fitzgerald LF, Kent JA. Rates of oxidative ATP synthesis are not augmented beyond the pH threshold in human vastus lateralis muscles during a stepwise contraction protocol. J Physiol 2021; 599:1997-2013. [PMID: 33576028 DOI: 10.1113/jp280851] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 02/05/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The oxygen cost of high-intensity exercise at power outputs above an individual's lactate threshold (LT) is greater than would be predicted by the linear oxygen consumption-power relationship observed below the LT. However, whether these augmentations are caused by an increased ATP cost of force generation (ATPCOST ) or an increased oxygen cost of ATP synthesis is unclear. We used 31 P-MRS to measure changes in cytosolic [ADP] (intramyocellular marker of oxidative metabolism), oxidative ATP synthesis (ATPOX ) and ATPCOST during a 6-stage, stepwise knee extension protocol. ATPCOST was unchanged across stages. The relationship between [ADP] and muscle power output was augmented at workloads above the pH threshold (pHT ; proxy for LT), whereas increases in ATPOX were attenuated. These results suggest the greater oxygen cost of contractions at workloads beyond the pHT is not caused by mechanisms that increase ATPCOST , but rather mechanisms that alter intrinsic mitochondrial function or capacity. ABSTRACT Increases in skeletal muscle metabolism and oxygen consumption are linearly related to muscle power output for workloads below the lactate threshold (LT), but are augmented (i.e. greater rate of increase relative to workload) thereafter. Presently, it is unclear whether these metabolic augmentations are caused by increases in the ATP cost of force generation (ATPCOST ) or changes in the efficiency of mitochondrial oxygen consumption and oxidative ATP synthesis (ATPOX ). To partition these two hypotheses in vivo, we used 31 P-MRS to calculate slopes relating step-changes in muscle work to concurrent changes in cytosolic phosphates and ATPOX before and after the pH threshold (pHT ; used here as a proxy for LT) within the vastus lateralis muscle of eight young adults during a stepwise knee extension test. Changes in muscle phosphates and ATPOX were linearly related to workload below the pHT . However, slopes above the pHT were greater for muscle phosphates (P < 0.05) and lower for ATPOX (P < 0.05) than were the slopes observed below the pHT . The maximal capacity for ATPOX ( V ̇ max ) and ADP-specific ATPOX also declined beyond the pHT (P < 0.05), whereas ATPCOST was unchanged (P = 0.10). These results oppose the hypothesis that high-intensity contractions increase ATPCOST and suggest that greater oxidative metabolism at workloads beyond the pHT is caused by mechanisms that affect intrinsic mitochondrial function or capacity, such as alterations in substrate selection or electron entry into the electron transport chain, temperature-mediated changes in mitochondrial permeability to protons, or stimulation of mitochondrial uncoupling by reactive oxygen species generation.
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Affiliation(s)
- Miles F Bartlett
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Liam F Fitzgerald
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Jane A Kent
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
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18
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Fullerton MM, Passfield L, MacInnis MJ, Iannetta D, Murias JM. Prior exercise impairs subsequent performance in an intensity- and duration-dependent manner. Appl Physiol Nutr Metab 2021; 46:976-985. [PMID: 33641346 DOI: 10.1139/apnm-2020-0689] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Prior constant-load exercise performed for 30-min at or above maximal lactate steady state (MLSSp) significantly impairs subsequent time-to-task failure (TTF) compared with TTF performed without prior exercise. We tested the hypothesis that TTF would decrease in relation to the intensity and the duration of prior exercise compared with a baseline TTF trial. Eleven individuals (6 males, 5 females, aged 28 ± 8 yrs) completed the following tests on a cycle ergometer (randomly assigned after MLSSp was determined): (i) a ramp-incremental test; (ii) a baseline TTF trial performed at 80% of peak power (TTFb); (iii) five 30-min constant-PO rides at 5% below lactate threshold (LT-5%), halfway between LT and MLSSp (Delta50), 5% below MLSSp (MLSS-5%), MLSSp, and 5% above MLSSp (MLSS+5%); and (iv) 15- and 45-min rides at MLSSp (MLSS15 and MLSS45, respectively). Each condition was immediately followed by a TTF trial at 80% of peak power. Compared with TTFb (330 ± 52 s), there was 8.0 ± 24.1, 23.6 ± 20.2, 41.0 ± 14.8, 52.2 ± 18.9, and 75.4 ± 7.4% reduction in TTF following LT-5%, Delta50, MLSS-5%, MLSSp, and MLSS+5%, respectively. Following MLSS15 and MLSS45 there were 29.0 ± 20.1 and 69.4 ± 19.6% reductions in TTF, respectively (P < 0.05). It is concluded that TTF is reduced following prior exercise of varying duration at MLSSp and at submaximal intensities below MLSS. Novelty: Prior constant-PO exercise, performed at intensities below MLSSp, reduces subsequent TTF performance. Subsequent TTF performance is reduced in a linear fashion following an increase in the duration of constant-PO exercise at MLSSp.
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Affiliation(s)
| | - Louis Passfield
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,School of Sport and Exercise Sciences, University of Kent, Canterbury, United Kingdom
| | | | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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19
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Towards Detecting Biceps Muscle Fatigue in Gym Activity Using Wearables. SENSORS 2021; 21:s21030759. [PMID: 33498702 PMCID: PMC7865622 DOI: 10.3390/s21030759] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/17/2022]
Abstract
Fatigue is a naturally occurring phenomenon during human activities, but it poses a bigger risk for injuries during physically demanding activities, such as gym activities and athletics. Several studies show that bicep muscle fatigue can lead to various injuries that may require up to 22 weeks of treatment. In this work, we adopt a wearable approach to detect biceps muscle fatigue during a bicep concentration curl exercise as an example of a gym activity. Our dataset consists of 3000 bicep curls from twenty middle-aged volunteers at ages between 27 to 30 and Body Mass Index (BMI) ranging between 18 to 28. All volunteers have been gym-goers for at least 1 year with no records of chronic diseases, muscle, or bone surgeries. We encountered two main challenges while collecting our dataset. The first challenge was the dumbbell's suitability, where we found that a dumbbell weight (4.5 kg) provides the best tradeoff between longer recording sessions and the occurrence of fatigue on exercises. The second challenge is the subjectivity of RPE, where we average the reported RPE with the measured heart rate converted to RPE. We observed from our data that fatigue reduces the biceps' angular velocity; therefore, it increases the completion time for later sets. We extracted a total of 33 features from our dataset, which have been reduced to 16 features. These features are the most overall representative and correlated with bicep curl movement, yet they are fatigue-specific features. We utilized these features in five machine learning models, which are Generalized Linear Models (GLM), Logistic Regression (LR), Random Forests (RF), Decision Trees (DT), and Feedforward Neural Networks (FNN). We found that using a two-layer FNN achieves an accuracy of 98% and 88% for subject-specific and cross-subject models, respectively. The results presented in this work are useful and represent a solid start for moving into a real-world application for detecting the fatigue level in bicep muscles using wearable sensors as we advise athletes to take fatigue into consideration to avoid fatigue-induced injuries.
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20
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Yoshimura M, Hojo T, Yamamoto H, Tachibana M, Nakamura M, Fukuoka Y. Effects of artificial CO 2-rich cold-water immersion on repeated-cycling work efficiency. Res Sports Med 2020; 30:215-227. [PMID: 33300394 DOI: 10.1080/15438627.2020.1860048] [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: 10/22/2022]
Abstract
We investigated the acute effects of cold-water immersion (20°C) with higher CO2 concentration (CCWI) following a high-intensity Wingate anaerobic exercise test (WAnT) on subjects' sublingual temperature (Tsub), blood lactate ([La]b), heart rate (HR), and aerobic cycling work efficiency (WE) compared to cold tap-water immersion (20°C; CWI) and passive recovery (PAS). Fifteen subjects completed three testing sessions at 1-week intervals. Each trial consisted of a first WE and WAnT, and a 20-min recovery intervention (randomized: CCWI, CWI, and PAS) before repeating a second WE and WAnT. The WE was measured by the metabolic demand during 50%V̇O2max exercise. HR, Tsub, and [La]b were recorded throughout the testing sessions. There was a significant decline in the WE from 1st bout to 2nd bout at each recovery intervention. The WAnT was also significantly reduced at 2nd bout. Significantly reduced [La]b was achieved at CCWI compared to PAS, but not to the CWI. Likewise, the reduction in HR following immersion was the largest at CCWI compared to the other conditions. These findings indicate that CCWI is an effective intervention for maintaining repeated cycling work efficiency, which might be associated with reduced [La]b and HR.
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Affiliation(s)
- Miho Yoshimura
- Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan
| | - Tatsuya Hojo
- Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan
| | - Hayato Yamamoto
- Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan
| | - Misato Tachibana
- Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan
| | - Masatoshi Nakamura
- Department of Physical Therapy, Niigata University of Health and Warfare, Niigata, Japan
| | - Yoshiyuki Fukuoka
- Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan
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21
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Schmitz B, Pfeifer C, Thorwesten L, Krüger M, Klose A, Brand SM. Yo-Yo Intermittent Recovery Level 1 Test for Estimation of Peak Oxygen Uptake: Use Without Restriction? RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2020; 91:478-487. [PMID: 32004114 DOI: 10.1080/02701367.2019.1684432] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/13/2019] [Indexed: 06/10/2023]
Abstract
Purpose: This study analyzed the physiological response during Yo-Yo Intermittent Recovery Level 1 (YYIR1) test and re-test by in-field ergospirometry and time-series analyses of respiratory parameters. Methods: Ten moderately trained males (23.4 ± 2.01 years, VO2peak= 56.81 ± 10.75 mL·kg-1·min-1) completed three running trials including two separate YYIR1 tests and an independent maximal performance running test with time-series analyses of gas exchange parameters. Physiological response was assessed during all tests by determination of blood lactate levels (including calculation of individual lactate threshold), heart rate, oxygen consumption and respiratory exchange ratio (RER). Results: Modeling of YYIR1 test mean VO2 uptake kinetics over all participants revealed that VO2 increased rapidly after the individual lactate threshold (11.49 ± 0.66 km∙h-1 at 3.83 ± 0.42 mmol∙L-1) was reached with ~95% VO2peak at ~50% of the test duration (test, VO2 50%= 95.17 ± 8.74% of VO2peak; re-test, VO2 50%= 96.78 ± 7.04% of VO2peak). However, and despite identical YYIR1 test performance (1568 ± 364.6 m vs. 1568 ± 449.7 m, CV = 4.59%), mean VO2peak during YYIR1 test was 8.81 ± 5.6% higher than YYIR1 re-test (p = .027). Importantly, correlation of VO2peak with YYIR1 test performance was weak (R2 = 0.28, p = .115). Conclusions: We conclude that the YYIR1 test should not be used to estimate VO2peak. Further studies on direct determination of gas exchange parameters during different YYI test variants are warranted.
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22
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de Lima LAP, Achiche S, de Lucas RD, Raison M. Second-order simultaneous components model for the overshoot and "slow component" in V̇O 2 kinetics. Respir Physiol Neurobiol 2020; 280:103479. [PMID: 32593589 DOI: 10.1016/j.resp.2020.103479] [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: 10/16/2019] [Revised: 06/05/2020] [Accepted: 06/11/2020] [Indexed: 10/24/2022]
Abstract
The human oxygen uptake responses to exercise step on-transients present different shapes depending on the overshoot and/or the "slow component" manifestations. The conventional First-Order Multi-Exponential (FOME) model incorporates delayed add-on terms to comprise these phenomena, increasing parameter quantity, requiring a delayed recruitment of type II fibers to explain the "slow component," and not offering a unified structure for different individuals and intensity domains. We hypothesized that a model composed of two Second-Order Simultaneous Components (SOSC) would present a better overall fitting performance than the FOME. Fourteen well-trained male cyclists performed repeated step on-transitions to moderate, heavy, and severe cycling intensities, whose responses were fitted with FOME and SOSC models. The SOSC presented significantly smaller (p < 0.05) root mean squared errors for moderate, supra-moderate, and all intensities combined. Along with conceptual analyses, these findings suggest the SOSC as a comprehensive alternative to the FOME model, explaining all oxygen uptake step responses with as many parameters and without delayed add-on components.
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Affiliation(s)
- Luis Antonio Pereira de Lima
- Mechanical Engineering Department of Polytechnique Montréal, 2500, Chemin de Polytechnique, H3T1J4, Montréal, QC, Canada.
| | - Sofiane Achiche
- Mechanical Engineering Department of Polytechnique Montréal, 2500, Chemin de Polytechnique, H3T1J4, Montréal, QC, Canada.
| | - Ricardo Dantas de Lucas
- Sports Centre, Federal University of Santa Catarina, Brazil Campus Universitário, 88040900, Florianópolis, SC, Brazil.
| | - Maxime Raison
- Mechanical Engineering Department of Polytechnique Montréal, 2500, Chemin de Polytechnique, H3T1J4, Montréal, QC, Canada.
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23
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Korzeniewski B, Rossiter HB. Exceeding a "critical" muscle P i: implications for [Formula: see text] and metabolite slow components, muscle fatigue and the power-duration relationship. Eur J Appl Physiol 2020; 120:1609-1619. [PMID: 32435984 DOI: 10.1007/s00421-020-04388-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/02/2020] [Indexed: 12/21/2022]
Abstract
PURPOSE The consequences of the assumption that the additional ATP usage, underlying the slow component of oxygen consumption ([Formula: see text]) and metabolite on-kinetics, starts when cytosolic inorganic phosphate (Pi) exceeds a certain "critical" Pi concentration, and muscle work terminates because of fatigue when Pi exceeds a certain, higher, "peak" Pi concentration are investigated. METHODS A previously developed computer model of the myocyte bioenergetic system is used. RESULTS Simulated time courses of muscle [Formula: see text], cytosolic ADP, pH, PCr and Pi at various ATP usage activities agreed well with experimental data. Computer simulations resulted in a hyperbolic power-duration relationship, with critical power (CP) as an asymptote. CP was increased, and phase II [Formula: see text] on-kinetics was accelerated, by progressive increase in oxygen tension (hyperoxia). CONCLUSIONS Pi is a major factor responsible for the slow component of the [Formula: see text] and metabolite on-kinetics, fatigue-related muscle work termination and hyperbolic power-duration relationship. The successful generation of experimental system properties suggests that the additional ATP usage, underlying the slow component, indeed starts when cytosolic Pi exceeds a "critical" Pi concentration, and muscle work terminates when Pi exceeds a "peak" Pi concentration. The contribution of other factors, such as cytosolic acidification, or glycogen depletion and central fatigue should not be excluded. Thus, a detailed quantitative unifying mechanism underlying various phenomena related to skeletal muscle fatigue and exercise tolerance is offered that was absent in the literature. This mechanism is driven by reciprocal stimulation of Pi increase and additional ATP usage when "critical" Pi is exceeded.
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Affiliation(s)
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Pulmonary and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA.,Faculty of Biological Sciences, University of Leeds, Leeds, UK
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24
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Gajanand T, Conde Alonso S, Ramos JS, Antonietti JP, Borrani F. Alterations to neuromuscular properties of skeletal muscle are temporally dissociated from the oxygen uptake slow component. Sci Rep 2020; 10:7728. [PMID: 32382067 PMCID: PMC7206089 DOI: 10.1038/s41598-020-64395-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/13/2020] [Indexed: 11/09/2022] Open
Abstract
To assess if the alteration of neuromuscular properties of knee extensors muscles during heavy exercise co-vary with the SCV ([Formula: see text] slow component), eleven healthy male participants completed an incremental ramp test to exhaustion and five constant heavy intensity cycling bouts of 2, 6, 10, 20 and 30 minutes. Neuromuscular testing of the knee extensor muscles were completed before and after exercise. Results showed a significant decline in maximal voluntary contraction (MVC) torque only after 30 minutes of exercise (-17.01% ± 13.09%; p < 0.05) while single twitch (PT), 10 Hz (P10), and 100 Hz (P100) doublet peak torque amplitudes were reduced after 20 and 30 minutes (p < 0.05). Voluntary activation (VA) and M-wave were not affected by exercise, but significant correlation was found between the SCV and PT, MVC, VA, P10, P100, and P10/P100 ratio, respectively (p < 0.015). Therefore, because the development of the SCV occurred mainly between 2-10 minutes, during which neuromuscular properties were relatively stable, and because PT, P10 and P100 were significantly reduced only after 20-30 minutes of exercise while SCV is stable, a temporal relationship between them does not appear to exist. These results suggest that the development of fatigue due to alterations of neuromuscular properties is not an essential requirement to elicit the SCV.
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Affiliation(s)
- Trishan Gajanand
- Department of Exercise Sciences, Faculty of Science, University of Auckland, Auckland, New Zealand.,School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Sonia Conde Alonso
- Institute of Sport Sciences of University of Lausanne (ISSUL), Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
| | - Joyce S Ramos
- SHAPE Research Centre, Exercise Science and Clinical Exercise Physiology, College of Nursing and Health Sciences, Flinders University, Bedford Park, South Australia, 5042, Australia
| | | | - Fabio Borrani
- Institute of Sport Sciences of University of Lausanne (ISSUL), Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Colosio AL, Teso M, Pogliaghi S. Prolonged static stretching causes acute, nonmetabolic fatigue and impairs exercise tolerance during severe-intensity cycling. Appl Physiol Nutr Metab 2020; 45:902-910. [PMID: 32176851 DOI: 10.1139/apnm-2019-0981] [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] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that static stretching, an acute, nonmetabolic fatiguing intervention, reduces exercise tolerance by increasing muscle activation and affecting muscle bioenergetics during cycling in the "severe" intensity domain. Ten active men (age, 24 ± 2 years; body mass, 74 ± 11 kg; height, 176 ± 8 cm) participated in identical constant-load cycling tests of equal intensity, of which 2 tests were carried out under control conditions and 2 were done after stretching. This resulted in a 5% reduction of maximal isokinetic sprinting power output. We measured (i) oxygen consumption, (ii) electromyography, (iii) deoxyhemoglobin, (iv) blood lactate concentration; (v) time to exhaustion, and (vi) perception of effort. Finally, oxygen consumption and deoxyhemoglobin kinetics were determined. Force reduction following stretching was accompanied by augmented muscle excitation at a given workload (p = 0.025) and a significant reduction in time to exhaustion (p = 0.002). The time to peak oxygen consumption was reduced by stretching (p = 0.034), suggesting an influence of the increased muscle excitation on the oxygen consumption kinetics. Moreover, stretching was associated with a mismatch between O2 delivery and utilization during the isokinetic exercise, increased perception of effort, and blood lactate concentration; these observations are all consistent with an increased contribution of the glycolytic energy system to sustain the same absolute intensity. These results suggest a link between exercise intolerance and the decreased ability to produce force. Novelty We provided the first characterization of the effects of prolonged stretching on the metabolic response during severe cycling. Stretching reduced maximal force and augmented muscle activation, which in turn increased the metabolic response to sustain exercise.
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Affiliation(s)
- Alessandro L Colosio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
| | - Massimo Teso
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
| | - Silvia Pogliaghi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
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IANNETTA DANILO, INGLIS ERINCALAINE, MATTU ANMOLT, FONTANA FEDERICOY, POGLIAGHI SILVIA, KEIR DANIELA, MURIAS JUANM. A Critical Evaluation of Current Methods for Exercise Prescription in Women and Men. Med Sci Sports Exerc 2020; 52:466-473. [DOI: 10.1249/mss.0000000000002147] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Corvino RB, Oliveira MFM, Denadai BS, Rossiter HB, Caputo F. Speeding of oxygen uptake kinetics is not different following low-intensity blood-flow-restricted and high-intensity interval training. Exp Physiol 2019; 104:1858-1867. [PMID: 31613029 DOI: 10.1113/ep087727] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 10/10/2019] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Can interval blood-flow-restricted (BFR) cycling training, undertaken at a low intensity, promote a similar adaptation to oxygen uptake ( V ̇ O 2 ) kinetics to high-intensity interval training? What is the main finding and its importance? Speeding of pulmonary V ̇ O 2 on-kinetics in healthy young subjects was not different between low-intensity interval BFR training and traditional high-intensity interval training. Given that very low workloads are well tolerated during BFR cycle training and speed V ̇ O 2 on-kinetics, this training method could be used when high mechanical loads are contraindicated. ABSTRACT Low-intensity blood-flow-restricted (BFR) endurance training is effective to increase aerobic capacity. Whether it speeds pulmonary oxygen uptake ( V ̇ O 2 p ), CO2 output ( V ̇ C O 2 p ) and ventilatory ( V ̇ Ep ) kinetics has not been examined. We hypothesized that low-intensity BFR training would reduce the phase 2 time constant (τp ) of V ̇ O 2 p , V ̇ C O 2 p and V ̇ Ep by a similar magnitude to traditional high-intensity interval training (HIT). Low-intensity interval training with BFR served as a control. Twenty-four participants (25 ± 6 years old; maximal V ̇ O 2 46 ± 6 ml kg-1 min-1 ) were assigned to one of the following: low-intensity BFR interval training (BFR; n = 8); low-intensity interval training without BFR (LOW; n = 7); or high-intensity interval training without BFR (HIT; n = 9). Training was 12 sessions of two sets of five to eight × 2 min cycling and 1 min resting intervals. LOW and BFR were conducted at 30% of peak incremental power (Ppeak ), and HIT was at ∼103% Ppeak . For BFR, cuffs were inflated on both thighs (140-200 mmHg) during exercise and deflated during rest intervals. Six moderate-intensity step transitions (30% Ppeak ) were averaged for analysis of pulmonary on-kinetics. Both BFR (pre- versus post-training τp = 18.3 ± 3.2 versus 14.5 ± 3.4 s; effect size = 1.14) and HIT (τp = 20.3 ± 4.0 versus 13.1 ± 2.9 s; effect size = 1.75) reduced the V ̇ O 2 p τp (P < 0.05). As expected, there was no change in LOW ( V ̇ O 2 p τp = 17.9 ± 6.2 versus 17.7 ± 4.3 s; P = 0.9). The kinetics of V ̇ C O 2 p and V ̇ Ep were speeded only after HIT (38.5 ± 10.6%, P < 0.001 and 31.2 ± 24.7%, P = 0.004, respectively). Both HIT and low-intensity BFR training were effective in speeding moderate-intensity V ̇ O 2 p kinetics. These data support the findings of others that low-intensity cycling training with BFR increases muscle oxidative capacity.
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Affiliation(s)
- Rogério B Corvino
- Human Performance Research Group, Center for Health and Exercise Science, Santa Catarina State University, Florianopolis, Brazil
| | - Mariana F M Oliveira
- Human Performance Research Group, Center for Health and Exercise Science, Santa Catarina State University, Florianopolis, Brazil.,Physical Effort Laboratory, Sports Center, Federal University of the State of Santa Catarina, Florianopolis, Brazil
| | - Benedito S Denadai
- Physical Effort Laboratory, Sports Center, Federal University of the State of Santa Catarina, Florianopolis, Brazil.,Human Performance Laboratory, São Paulo State University, Rio Claro, Brazil
| | - Harry B Rossiter
- Division of Pulmonary and Critical Care Physiology and Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Center at Harbor-UCLA Medical Center, Torrance, CA, USA.,School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Fabrizio Caputo
- Human Performance Research Group, Center for Health and Exercise Science, Santa Catarina State University, Florianopolis, Brazil
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Colosio AL, Baldessari E, Basso E, Pogliaghi S. Respiratory and muscular response to acute non-metabolic fatigue during ramp incremental cycling. Respir Physiol Neurobiol 2019; 270:103281. [PMID: 31425884 DOI: 10.1016/j.resp.2019.103281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/12/2019] [Accepted: 08/15/2019] [Indexed: 11/28/2022]
Abstract
We tested the hypothesis that acute, non-metabolic fatigue, by reducing maximal power output and possibly increasing muscle recruitment at a given exercise intensity, will reduce indexes of exercise tolerance during incremental cycling. Ten subjects performed three ramp incremental tests respectively after static stretching (STRC), dropjumps (DJ) or control (CTRL). Fatigue was assessed as reduction in maximal power output (sprintPO) during isokinetic sprints. During the ramps we measured: oxygen consumption (VO2), power output (PO), and surface electromyography. sprintPO was reduced after STRC and DJ (p = 0.007) yet not after CTRL. During the ramps, the interventions augmented muscle excitation vs CTRL (p ≤ 0.001). Peak PO and VO2 were reduced after STRC (302 ± 39W p = 0.033, 3365 ± 465 ml/min p = 0.015) and DJ (300 ± 37W p = 0.023, 3413 ± 476 ml/min p = 0.094) vs CTRL (314 ± 41W, 3505 ± 486 ml/min). Interventions were associated with early occurrence of the ventilatory thresholds and increased VO2 vs CTRL (p = 0.029). The physiological response after acute non-metabolic fatigue suggests a link between exercise intolerance and the decreased ability to produce force.
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Affiliation(s)
- Alessandro L Colosio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona, 37131, Italy
| | - Emmanuele Baldessari
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona, 37131, Italy
| | - Enrico Basso
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona, 37131, Italy
| | - Silvia Pogliaghi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona, 37131, Italy.
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do Nascimento Salvador PC, Schäfer L, Grassi B, Guglielmo LGA, Denadai BS. Changes in VO 2 Kinetics After Elevated Baseline Do Not Necessarily Reflect Alterations in Muscle Force Production in Both Sexes. Front Physiol 2019; 10:471. [PMID: 31073291 PMCID: PMC6495266 DOI: 10.3389/fphys.2019.00471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 04/04/2019] [Indexed: 11/13/2022] Open
Abstract
A link between muscle fatigue, decreased efficiency and the slow component of oxygen uptake (VO2sc) has been suggested. However, a cause-effect relationship remains to be elucidated. Although alterations in VO2 kinetics after elevated baseline work rate have previously been reported, to date no study has observed the effect on muscle force production (MFP) behavior considering physiological differences between male and female subjects. This study investigated the effect of elevated baseline work rate on the VO2 kinetics and MFP in 10 male and 10 female healthy subjects. Subjects performed 4 transitions of very-heavy (VH) intensity cycling in a randomized order after unloaded (U-VH) or moderate (M-VH) exercise. Maximal isokinetic efforts (MIE) were performed before and after each condition at two different cadences (60 or 120 rpm). Whereas baseline VO2 and time constant (τ) were significantly higher in M-VH compared to U-VH, the fundamental amplitude and the VO2 slow component (VO2sc) were significantly lower in M-VH (p < 0.05) in both sexes. Blood lactate concentration ([La]) and rate of perceived exertion (RPE) were not influenced by condition or sex (p > 0.05). The MFP post-exercise was not significantly influenced by condition in both sexes and cadences (Δtorque for males: at 60 rpm in U-VH = 13 ± 10 Nm, in M-VH = 13 ± 9 Nm; at 120 rpm in U-VH = 22 ± 14 Nm, in M-VH = 21 ± 12 Nm; for females: at 120 rpm in U-VH = 10 ± 9 Nm, in M-VH = 12 ± 8 Nm; p > 0.05), with the exception that female subjects presented smaller decreases in M-UH at 60 rpm compared to U-VH (11 ± 13 vs. 18 ± 14 Nm, respectively, p < 0.05). There was no correlation between the decrease in torque production and VO2 kinetics parameters (p > 0.05). The alterations in VO2 kinetics which have been suggested to be linked to changes in motor unit recruitment after elevated baseline work rate did not reflect alterations in MFP and fatigue in both sexes.
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Affiliation(s)
- Paulo Cesar do Nascimento Salvador
- Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, Florianopolis, Brazil.,Leonardo da Vinci University/Uniasselvi, Indaial, Brazil
| | - Lisa Schäfer
- School of Sport and Service Management, University of Brighton, Eastbourne, United Kingdom
| | - Bruno Grassi
- Exercise Physiology Laboratory, Department of Medicine, Università Degli Studi di Udine, Udine, Italy
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Goulding RP, Roche DM, Marwood S. "Work-to-Work" exercise slows pulmonary oxygen uptake kinetics, decreases critical power, and increases W' during supine cycling. Physiol Rep 2018; 6:e13916. [PMID: 30426722 PMCID: PMC6234148 DOI: 10.14814/phy2.13916] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/15/2018] [Indexed: 01/21/2023] Open
Abstract
We have previously demonstrated that the phase II time constant of pulmonary oxygen uptake kinetics ( τ v ˙ o 2 ) is an independent determinant of critical power (CP) when O2 availability is not limiting, that is, during upright cycle exercise in young, healthy individuals. Whether this causative relationship remains when O2 availability is impaired remains unknown. During supine exercise, which causes an O2 availability limitation during the exercise transition, we therefore determined the impact of a raised baseline work rate on τ v ˙ o 2 and CP. CP, τ v ˙ o 2 , and muscle oxygenation status (the latter via near-infrared spectroscopy) were determined via four severe-intensity constant-power exercise tests completed in two conditions: (1) with exercise initiated from an unloaded cycling baseline (U→S), and (2) with exercise initiated from a moderate-intensity baseline work rate of 90% of the gas exchange threshold (M→S). In M→S, critical power was lower (U→S = 146 ± 39 W vs. M→S = 132 ± 33 W, P = 0.023) and τ v ˙ o 2 was greater (U→S = 45 ± 16 sec, vs. M→S = 69 ± 129 sec, P = 0.001) when compared to U→S. There was no difference in tissue oxyhemoglobin concentration ([HbO2 + MbO2 ]) at baseline or during exercise. The concomitant increase in τ v ˙ o 2 and reduction in CP during M→S compared to U→S shows for the first time that τ v ˙ o 2 is an independent determinant of CP in conditions where O2 availability is limiting.
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Affiliation(s)
- Richie P. Goulding
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Denise M. Roche
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Simon Marwood
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
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Halder A, Gao C, Miller M, Kuklane K. Oxygen uptake and muscle activity limitations during stepping on a stair machine at three different climbing speeds. ERGONOMICS 2018; 61:1382-1394. [PMID: 29785880 DOI: 10.1080/00140139.2018.1473644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
This laboratory study examined human stair ascending capacity and constraining factors including legs' local muscle fatigue (LMF) and cardiorespiratory capacity. Twenty-five healthy volunteers, with mean age 35.3 years, maximal oxygen uptake (VO2max) of 46.7 mL·min-1·kg-1 and maximal heart rate (HR) of 190 bpm, ascended on a stair machine at 60 and 75% (3 min each) and 90% of VO2max (5 min or until exhaustion). The VO2, maximal heart rate (HRmax) and electromyography (EMG) of the leg muscles were measured. The average VO2highest reached 43.9 mL·min-1·kg-1, and HRhighest peaked at 185 bpm at 90% of VO2max step rate (SR). EMG amplitudes significantly increased at all three levels, p < .05, and median frequencies decreased mostly at 90% of VO2max SR evidencing leg LMF. Muscle activity interpretation squares were developed and effectively used to observe changes over time, confirming LMF. The combined effects of LMF and cardiorespiratory constraints reduced ascending tolerance and constrained the duration to 4.32 min. Practitioner Summary: To expedite ascending evacuation from high-rise buildings and deep underground structures, it is necessary to consider human physical load. This study investigated the limiting physiological factors and muscle activity rate changes (MARC) used in the muscle activity interpretation squares (MAIS) to evaluate leg local muscle fatigue (LMF). LMF and cardiorespiratory capacity significantly constrain human stair ascending capacities at high, constant step rates.
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Affiliation(s)
- Amitava Halder
- a Division of Ergonomics and Aerosol Technology, Department of Design Sciences , Lund University , Lund , Sweden
| | - Chuansi Gao
- a Division of Ergonomics and Aerosol Technology, Department of Design Sciences , Lund University , Lund , Sweden
| | - Michael Miller
- b Department of Health Sciences, Faculty of Medicine , Lund University , Lund , Sweden
| | - Kalev Kuklane
- a Division of Ergonomics and Aerosol Technology, Department of Design Sciences , Lund University , Lund , Sweden
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32
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Pornsuriyasak P, Rambod M, Effros RM, Casaburi R, Porszasz J. Oxygen Uptake and Lactate Kinetics in Patients with Chronic Obstructive Pulmonary Disease during Heavy Intensity Exercise: Role of Pedaling Cadence. COPD 2018; 15:283-293. [PMID: 30156941 DOI: 10.1080/15412555.2018.1487391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Oxygen uptake slow component ([Formula: see text]sc) is associated with lactate accumulation, likely a contribution of poorly oxidative muscle fibers. We aimed to test the hypothesis that higher muscle tension during slow pedaling rates would yield more prominent [Formula: see text]sc in healthy subjects, but not in COPD patients. Eight severe COPD patients and 8 age-matched healthy individuals performed 4 rest-heavy exercise transitions at 40 and 80 RPM. Work rates at the two cadences were balanced. Venous blood was sampled for measurement of lactate concentration at rest and every 2 minutes until the end of exercise. [Formula: see text] kinetics were analyzed utilizing nonlinear regression. [Formula: see text] phase II amplitudes at the two cadences were similar in both groups. In healthy individuals, [Formula: see text]sc was steeper at 40 than 80 RPM (46.6 ± 12.0 vs. 29.5 ± 11.7 mL/min2, p = 0.002) but not in COPD patients (16.2 ± 14.7 vs. 13.3 ± 7.6 mL/min2). End-exercise lactate concentration did not differ between cadences in either group. In healthy individuals, greater slow-cadence [Formula: see text]sc seems likely related to oxidative muscle fiber recruitment at higher muscular tension. COPD patients, known to have fast-twitch fiber predominance, might be unable to recruit oxidative fibers at high muscle tension, blunting [Formula: see text]sc response.
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Affiliation(s)
- Prapaporn Pornsuriyasak
- a Division of Pulmonary and Critical Care, Faculty of Medicine , Ramathibodi Hospital, Mahidol University , Bangkok , Thailand
| | - Mehdi Rambod
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA.,c Division of Cardiology , University of Vermont College of Medicine , Burlington , Vermont , USA
| | - Richard M Effros
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
| | - Richard Casaburi
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
| | - Janos Porszasz
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
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Goulding RP, Roche DM, Marwood S. Elevated baseline work rate slows pulmonary oxygen uptake kinetics and decreases critical power during upright cycle exercise. Physiol Rep 2018; 6:e13802. [PMID: 30039557 PMCID: PMC6056736 DOI: 10.14814/phy2.13802] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 06/26/2018] [Indexed: 01/08/2023] Open
Abstract
Critical power is a fundamental parameter defining high-intensity exercise tolerance, and is related to the phase II time constant of pulmonary oxygen uptake kinetics (τV˙O2). Whether this relationship is causative is presently unclear. This study determined the impact of raised baseline work rate, which increases τV˙O2, on critical power during upright cycle exercise. Critical power was determined via four constant-power exercise tests to exhaustion in two conditions: (1) with exercise initiated from an unloaded cycling baseline (U→S), and (2) with exercise initiated from a baseline work rate of 90% of the gas exchange threshold (M→S). During these exercise transitions, τV˙O2 and the time constant of muscle deoxyhemoglobin kinetics (τ[HHb + Mb] ) (the latter via near-infrared spectroscopy) were determined. In M→S, critical power was lower (M→S = 203 ± 44 W vs. U→S = 213 ± 45 W, P = 0.011) and τV˙O2 was greater (M→S = 51 ± 14 sec vs. U→S = 34 ± 16 sec, P = 0.002) when compared with U→S. Additionally, τ[HHb + Mb] was greater in M→S compared with U→S (M→S = 28 ± 7 sec vs. U→S = 14 ± 7 sec, P = 0.007). The increase in τV˙O2 and concomitant reduction in critical power in M→S compared with U→S suggests a causal relationship between these two parameters. However, that τ[HHb + Mb] was greater in M→S exculpates reduced oxygen availability as being a confounding factor. These data therefore provide the first experimental evidence that τV˙O2 is an independent determinant of critical power. Keywords critical power, exercise tolerance, oxygen uptake kinetics, power-duration relationship, muscle deoxyhemoglobin kinetics, work-to-work exercise.
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Affiliation(s)
- Richie P. Goulding
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Denise M. Roche
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Simon Marwood
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
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Keir DA, Paterson DH, Kowalchuk JM, Murias JM. Using ramp-incremental V̇O 2 responses for constant-intensity exercise selection. Appl Physiol Nutr Metab 2018; 43:882-892. [PMID: 29570982 DOI: 10.1139/apnm-2017-0826] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite compelling evidence to the contrary, the view that oxygen uptake (V̇O2) increases linearly with exercise intensity (e.g., power output, speed) until reaching its maximum persists within the exercise physiology literature. This viewpoint implies that the V̇O2 response at any constant intensity is predictable from a ramp-incremental exercise test. However, the V̇O2 versus task-specific exercise intensity relationship constructed from ramp-incremental versus constant-intensity exercise are not equivalent preventing the use of V̇O2 responses from 1 domain to predict those of the other. Still, this "linear" translational framework continues to be adopted as the guiding principle for aerobic exercise prescription and there remains in the sport science literature a lack of understanding of how to interpret V̇O2 responses to ramp-incremental exercise and how to use those data to assign task-specific constant-intensity exercise. The objectives of this paper are to (i) review the factors that disassociate the V̇O2 versus exercise intensity relationship between ramp-incremental and constant-intensity exercise paradigms; (ii) identify when it is appropriate (or not) to use ramp V̇O2 responses to accurately assign constant-intensity exercise; and (iii) illustrate the technical and theoretical challenges with prescribing constant-intensity exercise solely on information acquired from ramp-incremental tests. Actual V̇O2 data collected during cycling exercise and V̇O2 kinetics modelling are presented to exemplify these concepts. Possible solutions to overcome these challenges are also presented to inform on appropriate intensity selection for individual-specific aerobic exercise prescription in both research and practical settings.
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Affiliation(s)
- Daniel A Keir
- a University Health Network, Department of Medicine, Toronto, Ontario, Canada.,b Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada.,c School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Donald H Paterson
- b Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada.,c School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - John M Kowalchuk
- b Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada.,c School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada.,d Department of Physiology and Pharmacology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Juan M Murias
- e Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada
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do Nascimento Salvador PC, Souza KMD, De Lucas RD, Guglielmo LGA, Denadai BS. The effects of priming exercise on the V̇O 2 slow component and the time-course of muscle fatigue during very-heavy-intensity exercise in humans. Appl Physiol Nutr Metab 2018; 43:909-919. [PMID: 29566544 DOI: 10.1139/apnm-2017-0769] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that prior exercise would attenuate the muscle fatigue accompanied by oxygen uptake slow-component (V̇O2SC) behavior during a subsequent very-heavy (VH)-intensity cycling exercise. Thirteen healthy male subjects performed tests to determine the critical power (CP) and the fixed amount of work above CP ([Formula: see text]) and performed 6 square-wave bouts until 3 or 8 min, each at a work rate set to deplete 70% [Formula: see text] in 8 min, with a maximal isokinetic effort before and after the conditions without (VHCON) and with prior exercise (VHEXP), to measure the cycling peak torque decrement. The V̇O2SC magnitude at 3 min (VHCON = 0.280 ± 0.234, VHEXP = 0.116 ± 0.109 L·min-1; p = 0.04) and the V̇O2SC trajectory were significantly lower for VHEXP (VHCON = 0.108 ± 0.042, VHEXP = 0.063 ± 0.031 L·min-2; p < 0.01), leading to a V̇O2SC magnitude at the eighth minute that was significantly lower than VHCON (VHCON = 0.626 ± 0.296 L·min-1, VHEXP = 0.337 ± 0.179; p < 0.01). Conversely, peak torque progressively decreased from pre-exercise to 3 min (Δtorque = 21.5 ± 7.7 vs. 19.6 ± 9.2 Nm) and to 8 min (Δtorque = 29.4 ± 15.8 vs. 27.5 ± 12.0 Nm) at VHCON and VHEXP, respectively, without significant differences between conditions. Regardless of the condition, there was a significant relationship between Δtorque and the V̇O2SC (R2: VHCON = 0.23, VHEXP = 0.25; p = 0.01). Considering that "priming" effects on the V̇O2SC were not accompanied by the muscle force behavior, these findings do not support the hypothesis of a "causal" relationship between the time-course of muscle fatigue and V̇O2SC.
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Affiliation(s)
| | - Kristopher Mendes de Souza
- a Physical effort Laboratory, Sports Center, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil
| | - Ricardo Dantas De Lucas
- a Physical effort Laboratory, Sports Center, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil
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Halder A, Kuklane K, Gao C, Miller M, Delin M, Norén J, Fridolf K. Limitations of oxygen uptake and leg muscle activity during ascending evacuation in stairways. APPLIED ERGONOMICS 2018; 66:52-63. [PMID: 28958430 DOI: 10.1016/j.apergo.2017.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Stair ascending performance is critical during evacuation from buildings and underground infrastructures. Healthy subjects performed self-paced ascent in three settings: 13 floor building, 31 floor building, 33 m stationary subway escalator. To investigate leg muscle and cardiorespiratory capacities and how they constrain performance, oxygen uptake (VO2), heart rate (HR) and ascending speed were measured in all three; electromyography (EMG) in the first two. The VO2 and HR ranged from 89 to 96% of the maximum capacity reported in the literature. The average highest VO2 and HR ranged from 39 to 41 mL·kg-1·min-1 and 162 to 174 b·min-1, respectively. The subjects were able to sustain their initial preferred maximum pace for a short duration, while the average step rate was 92-95 steps·min-1. In average, VO2 reached relatively stable values at ≈37 mL·kg-1·min-1. EMG amplitudes decreased significantly and frequencies were unchanged. Speed reductions indicate that climbing capacity declined in the process of fatigue development. In the two buildings, the reduction of muscle power allowed the subjects to extend their tolerance and complete ascents in the 48 m and 109 m high stairways in 2.9 and 7.8 min, respectively. Muscle activity interpretation squares were developed and proved advantageous to observe fatigue and recovery over time.
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Affiliation(s)
- Amitava Halder
- Thermal Environment Laboratory, Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden.
| | - Kalev Kuklane
- Thermal Environment Laboratory, Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden
| | - Chuansi Gao
- Thermal Environment Laboratory, Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden
| | - Michael Miller
- Department of Health Sciences, Faculty of Medicine, Lund University, Sweden
| | | | - Johan Norén
- Brand & Riskingenjörerna AB (BRIAB), Stockholm, Sweden
| | - Karl Fridolf
- Division of Fire Safety Engineering, Department of Building and Environmental Technology, Faculty of Engineering, Lund University, Sweden; WSP Sverige AB, Malmö, Sweden
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Davies MJ, Benson AP, Cannon DT, Marwood S, Kemp GJ, Rossiter HB, Ferguson C. Dissociating external power from intramuscular exercise intensity during intermittent bilateral knee-extension in humans. J Physiol 2017; 595:6673-6686. [PMID: 28776675 PMCID: PMC5663836 DOI: 10.1113/jp274589] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/28/2017] [Indexed: 12/25/2022] Open
Abstract
Key points Continuous high‐intensity constant‐power exercise is unsustainable, with maximal oxygen uptake (V˙O2 max ) and the limit of tolerance attained after only a few minutes. Performing the same power intermittently reduces the O2 cost of exercise and increases tolerance. The extent to which this dissociation is reflected in the intramuscular bioenergetics is unknown. We used pulmonary gas exchange and 31P magnetic resonance spectroscopy to measure whole‐body V˙O2, quadriceps phosphate metabolism and pH during continuous and intermittent exercise of different work:recovery durations. Shortening the work:recovery durations (16:32 s vs. 32:64 s vs. 64:128 s vs. continuous) at a work rate estimated to require 110% peak aerobic power reduced V˙O2, muscle phosphocreatine breakdown and muscle acidification, eliminated the glycolytic‐associated contribution to ATP synthesis, and increased exercise tolerance. Exercise intensity (i.e. magnitude of intramuscular metabolic perturbations) can be dissociated from the external power using intermittent exercise with short work:recovery durations.
Abstract Compared with work‐matched high‐intensity continuous exercise, intermittent exercise dissociates pulmonary oxygen uptake (V˙O2) from the accumulated work. The extent to which this reflects differences in O2 storage fluctuations and/or contributions from oxidative and substrate‐level bioenergetics is unknown. Using pulmonary gas‐exchange and intramuscular 31P magnetic resonance spectroscopy, we tested the hypotheses that, at the same power: ATP synthesis rates are similar, whereas peak V˙O2 amplitude is lower in intermittent vs. continuous exercise. Thus, we expected that: intermittent exercise relies less upon anaerobic glycolysis for ATP provision than continuous exercise; shorter intervals would require relatively greater fluctuations in intramuscular bioenergetics than in V˙O2 compared to longer intervals. Six men performed bilateral knee‐extensor exercise (estimated to require 110% peak aerobic power) continuously and with three different intermittent work:recovery durations (16:32, 32:64 and 64:128 s). Target work duration (576 s) was achieved in all intermittent protocols; greater than continuous (252 ± 174 s; P < 0.05). Mean ATP turnover rate was not different between protocols (∼43 mm min−1 on average). However, the intramuscular phosphocreatine (PCr) component of ATP generation was greatest (∼30 mm min−1), and oxidative (∼10 mm min−1) and anaerobic glycolytic (∼1 mm min−1) components were lowest for 16:32 and 32:64 s intermittent protocols, compared to 64:128 s (18 ± 6, 21 ± 10 and 10 ± 4 mm min−1, respectively) and continuous protocols (8 ± 6, 20 ± 9 and 16 ± 14 mm min−1, respectively). As intermittent work duration increased towards continuous exercise, ATP production relied proportionally more upon anaerobic glycolysis and oxidative phosphorylation, and less upon PCr breakdown. However, performing the same high‐intensity power intermittently vs. continuously reduced the amplitude of fluctuations in V˙O2 and intramuscular metabolism, dissociating exercise intensity from the power output and work done. Continuous high‐intensity constant‐power exercise is unsustainable, with maximal oxygen uptake (V˙O2 max ) and the limit of tolerance attained after only a few minutes. Performing the same power intermittently reduces the O2 cost of exercise and increases tolerance. The extent to which this dissociation is reflected in the intramuscular bioenergetics is unknown. We used pulmonary gas exchange and 31P magnetic resonance spectroscopy to measure whole‐body V˙O2, quadriceps phosphate metabolism and pH during continuous and intermittent exercise of different work:recovery durations. Shortening the work:recovery durations (16:32 s vs. 32:64 s vs. 64:128 s vs. continuous) at a work rate estimated to require 110% peak aerobic power reduced V˙O2, muscle phosphocreatine breakdown and muscle acidification, eliminated the glycolytic‐associated contribution to ATP synthesis, and increased exercise tolerance. Exercise intensity (i.e. magnitude of intramuscular metabolic perturbations) can be dissociated from the external power using intermittent exercise with short work:recovery durations.
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Affiliation(s)
- Matthew J Davies
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK
| | - Alan P Benson
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK
| | - Daniel T Cannon
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, CA, USA
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, UK
| | - Graham J Kemp
- Magnetic Resonance & Image Analysis Research Centre, University of Liverpool, Liverpool, UK.,Department of Musculoskeletal Biology, University of Liverpool, Liverpool, UK
| | - Harry B Rossiter
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.,Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK
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McCrudden MC, Keir DA, Belfry GR. The effects of short work vs. longer work periods within intermittent exercise on V̇o 2p kinetics, muscle deoxygenation, and energy system contribution. J Appl Physiol (1985) 2017; 122:1435-1444. [PMID: 28336535 DOI: 10.1152/japplphysiol.00514.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 02/21/2017] [Accepted: 03/16/2017] [Indexed: 11/22/2022] Open
Abstract
We examined the effects of inserting 3-s recovery periods during high-intensity cycling exercise at 25-s and 10-s intervals on pulmonary oxygen uptake (V̇o2p), muscle deoxygenation [deoxyhemoglobin (HHb)], their associated kinetics (τ), and energy system contributions. Eleven men (24 ± 3 yr) completed two trials of three cycling protocols: an 8-min continuous protocol (CONT) and two 8-min intermittent exercise protocols with work-to-rest periods of 25 s to 3 s (25INT) and 10 s to 3 s (10INT). Each protocol began with a step-transition from a 20-W baseline to a power output (PO) of 60% between lactate threshold and maximal V̇o2p (Δ60). This PO was maintained for 8 min in CONT, whereas 3-s periods of 20-W cycling were inserted every 10 s and 25 s after the transition to Δ60 in 10INT and 25INT, respectively. Breath-by-breath gas exchange measured by mass spectrometry and turbine and vastus lateralis [HHb] measured by near-infrared spectroscopy were recorded throughout. Arterialized-capillary lactate concentration ([Lac-]) was obtained before and 2 min postexercise. The τV̇o2p was lowest (P < 0.05) for 10INT (24 ± 4 s) and 25INT (23 ± 5 s) compared with CONT (28 ± 4 s), whereas HHb kinetics did not differ (P > 0.05) between conditions. Postexercise [Lac-] was lowest (P < 0.05) for 10INT (7.0 ± 1.7 mM), was higher for 25INT (10.3 ± 1.9 mM), and was greatest in CONT (14.3 ± 3.1 mM). Inserting 3-s recovery periods during heavy-intensity exercise speeded V̇o2p kinetics and reduced overall V̇o2p, suggesting an increased reliance on PCr-derived phosphorylation during the work period of INT compared with an identical PO performed continuously.NEW & NOTEWORTHY We report novel observations on the effects of differing heavy-intensity work durations between 3-s recovery periods on pulmonary oxygen uptake (V̇o2p) kinetics, muscle deoxygenation, and energy system contributions. Relative to continuous exercise, V̇o2p kinetics are faster in intermittent exercise, and increased frequency of 3-s recovery periods improves microvascular O2 delivery and reduces V̇o2p and arterialized-capillary lactate concentration. The metabolic burden of identical intensity work is altered when performed intermittently vs. continuously.
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Affiliation(s)
- Michael C McCrudden
- School of Kinesiology, Canadian Center for Activity and Aging, University of Western Ontario, London, Ontario, Canada
| | - Daniel A Keir
- School of Kinesiology, Canadian Center for Activity and Aging, University of Western Ontario, London, Ontario, Canada
| | - Glen R Belfry
- School of Kinesiology, Canadian Center for Activity and Aging, University of Western Ontario, London, Ontario, Canada
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Sandage MJ, Smith AG. Muscle Bioenergetic Considerations for Intrinsic Laryngeal Skeletal Muscle Physiology. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2017; 60:1254-1263. [PMID: 28505224 DOI: 10.1044/2016_jslhr-s-16-0192] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/27/2016] [Indexed: 06/07/2023]
Abstract
PURPOSE Intrinsic laryngeal skeletal muscle bioenergetics, the means by which muscles produce fuel for muscle metabolism, is an understudied aspect of laryngeal physiology with direct implications for voice habilitation and rehabilitation. The purpose of this review is to describe bioenergetic pathways identified in limb skeletal muscle and introduce bioenergetic physiology as a necessary parameter for theoretical models of laryngeal skeletal muscle function. METHOD A comprehensive review of the human intrinsic laryngeal skeletal muscle physiology literature was conducted. Findings regarding intrinsic laryngeal muscle fiber complement and muscle metabolism in human models are summarized and exercise physiology methodology is applied to identify probable bioenergetic pathways used for voice function. RESULTS Intrinsic laryngeal skeletal muscle fibers described in human models support the fast, high-intensity physiological requirements of these muscles for biological functions of airway protection. Inclusion of muscle bioenergetic constructs in theoretical modeling of voice training, detraining, fatigue, and voice loading have been limited. CONCLUSIONS Muscle bioenergetics, a key component for muscle training, detraining, and fatigue models in exercise science, is a little-considered aspect of intrinsic laryngeal skeletal muscle physiology. Partnered with knowledge of occupation-specific voice requirements, application of bioenergetics may inform novel considerations for voice habilitation and rehabilitation.
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40
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The relationship between oxygen uptake kinetics and neuromuscular fatigue in high-intensity cycling exercise. Eur J Appl Physiol 2017; 117:969-978. [DOI: 10.1007/s00421-017-3585-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 03/06/2017] [Indexed: 10/19/2022]
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41
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De Ruiter CJ, Mallee MIP, Leloup LEC, De Haan A. A submaximal test for the assessment of knee extensor endurance capacity. Med Sci Sports Exerc 2017; 46:398-406. [PMID: 23877376 DOI: 10.1249/mss.0b013e3182a59c9c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We aimed to develop an undemanding test for endurance capacity of the knee extensor muscles, which can also be applied to frail participants. We hypothesized 1) that the first objective indications for peripheral fatigue during incremental unilateral repetitive isometric knee extensor contractions could be used to assess a fatigue threshold (FT), 2) that torque at FT would depend on training status, and 3) that this torque could easily be sustained for 30 min. METHODS Five trained and five untrained participants performed 5-min bouts of 60 repetitive contractions (3-s on and 2-s off). Torque, set at 25% maximal voluntary contraction (MVC), was increased by 5% MVC in subsequent bouts. The highest torque for which rectified surface EMG remained stable during the bout was defined as the FT. On separate occasions, 30-min bouts were performed at and above the FT to assess sustainable torque. Changes in gas exchange parameters, HR, and RPE were monitored to corroborate FT. RESULTS At FT (RPE = 5.7 ± 1.7), torque was higher (P < 0.05) in trained (41.4% ± 5.8% MVC) than in untrained participants (30.5% ± 1.8% MVC). Sustainable torque was ∼4% higher than (P < 0.05) and significantly related to FT (r(2) = 0.79). When torque was increased by 5% MVC, significant increases in rectified surface EMG and V˙O2 were found. CONCLUSIONS During incremental knee extensor contractions, FT could be assessed at a submaximal exercise intensity. FT was higher in trained than in untrained participants and was related to exercise sustainability. With the use of FT, changes in endurance capacity of single muscle groups can potentially also be determined in frail participants for whom exercise performed until exhaustion is unwarranted.
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42
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Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc 2016; 48:2320-2334. [PMID: 27031742 PMCID: PMC5070974 DOI: 10.1249/mss.0000000000000939] [Citation(s) in RCA: 299] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
: The hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise, and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power [CP]) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles-respiratory, metabolic, and contractile-within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2max is attained, and intolerance is manifested. CP may be regarded as a "fatigue threshold" in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
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Affiliation(s)
- David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas, U.S.A
| | - Mark Burnley
- School of Sport and Exercise Sciences, University of Kent, Chatham, U.K
| | - Anni Vanhatalo
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
| | - Harry B. Rossiter
- Faculty of Biological Sciences University of Leeds, Leeds, U.K
- Rehabilitaion Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, U.S.A
| | - Andrew M. Jones
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
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Hopker JG, Caporaso G, Azzalin A, Carpenter R, Marcora SM. Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise. Front Physiol 2016; 7:463. [PMID: 27790156 PMCID: PMC5061996 DOI: 10.3389/fphys.2016.00463] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 09/27/2016] [Indexed: 11/14/2022] Open
Abstract
The V˙O2 slow component (V˙O2sc) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min−1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and V˙O2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03), the V˙O2sc was not significantly different between the pre-fatigue (464 ± 301 mL·min−1) and the control (556 ± 223 mL·min−1) condition (P = 0.50). Blood lactate response was not significantly different between conditions (P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the V˙O2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the V˙O2sc is strongly associated with locomotor muscle fatigue.
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Affiliation(s)
- James G Hopker
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent Chatham, UK
| | - Giuseppe Caporaso
- Endurance Research Group, School of Sport and Exercise Sciences, University of KentChatham, UK; Applied Sport Science Research Group, School of Health, Sport and Bioscience, University of East LondonLondon, UK
| | - Andrea Azzalin
- Endurance Research Group, School of Sport and Exercise Sciences, University of KentChatham, UK; Leicester City Football ClubLeicester, UK
| | - Roger Carpenter
- Applied Sport Science Research Group, School of Health, Sport and Bioscience, University of East London London, UK
| | - Samuele M Marcora
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent Chatham, UK
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Keir DA, Robertson TC, Benson AP, Rossiter HB, Kowalchuk JM. The influence of metabolic and circulatory heterogeneity on the expression of pulmonary oxygen uptake kinetics in humans. Exp Physiol 2016; 101:176-92. [PMID: 26537768 DOI: 10.1113/ep085338] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 10/30/2015] [Indexed: 11/08/2022]
Abstract
We examined the relationship amongst baseline work rate (WR), phase II pulmonary oxygen uptake (V̇(O2p)) time constant (τV̇(O2p)) and functional gain (G(P)=ΔV̇(O2p)/ΔWR) during moderate-intensity exercise. Transitions were initiated from a constant or variable baseline WR. A validated circulatory model was used to examine the role of heterogeneity in muscle metabolism (V̇(O2m)) and blood flow (Q̇(m)) in determining V̇(O2p) kinetics. We hypothesized that τV̇(O2p) and G(P) would be invariant in the constant baseline condition but would increase linearly with increased baseline WR. Fourteen men completed three to five repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100 and 120 W on a cycle ergometer. The ∆40 W step transitions from 60, 80, 100 and 120 W were preceded by 6 min of 20 W cycling, from which the progressive ΔWR transitions (constant baseline condition) were examined. The V̇(O2p) was measured breath by breath using mass spectrometry and a volume turbine. For a given ΔWR, both τV̇(O2p) (22-35 s) and G(P) (8.7-10.5 ml min(-1) W(-1)) increased (P < 0.05) linearly as a function of baseline WR (20-120 W). The τV̇(O2p) was invariant (P < 0.05) in transitions initiated from 20 W, but G(P) increased with ΔWR (P < 0.05). Modelling the summed influence of multiple muscle compartments revealed that τV̇(O2p) could appear fast (24 s), and similar to in vivo measurements (22 ± 6 s), despite being derived from τV̇(O2p) values with a range of 15-40 s and τQ̇(m) with a range of 20-45 s, suggesting that within the moderate-intensity domain phase II V̇(O2p) kinetics are slowed dependent on the pretransition WR and are strongly influenced by muscle metabolic and circulatory heterogeneity.
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Affiliation(s)
- Daniel A Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Taylor C Robertson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Alan P Benson
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada
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45
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Cannon DT, Coelho AC, Cao R, Cheng A, Porszasz J, Casaburi R, Rossiter HB. Skeletal muscle power and fatigue at the tolerable limit of ramp-incremental exercise in COPD. J Appl Physiol (1985) 2016; 121:1365-1373. [PMID: 27660300 DOI: 10.1152/japplphysiol.00660.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/30/2016] [Accepted: 09/19/2016] [Indexed: 11/22/2022] Open
Abstract
Muscle fatigue (a reduced power for a given activation) is common following exercise in chronic obstructive pulmonary disease (COPD). Whether muscle fatigue, and reduced maximal voluntary locomotor power, are sufficient to limit whole body exercise in COPD is unknown. We hypothesized in COPD: 1) exercise is terminated with a locomotor muscle power reserve; 2) reduction in maximal locomotor power is related to ventilatory limitation; and 3) muscle fatigue at intolerance is less than age-matched controls. We used a rapid switch from hyperbolic to isokinetic cycling to measure the decline in peak isokinetic power at the limit of incremental exercise ("performance fatigue") in 13 COPD patients (FEV1 49 ± 17%pred) and 12 controls. By establishing the baseline relationship between muscle activity and isokinetic power, we apportioned performance fatigue into the reduction in muscle activation and muscle fatigue. Peak isokinetic power at intolerance was ~130% of peak incremental power in controls (274 ± 73 vs. 212 ± 84 W, P < 0.05), but ~260% in COPD patients (187 ± 141 vs. 72 ± 34 W, P < 0.05), greater than controls (P < 0.05). Muscle fatigue as a fraction of baseline peak isokinetic power was not different in COPD patients vs. controls (0.11 ± 0.20 vs. 0.19 ± 0.11). Baseline to intolerance, the median frequency of maximal isokinetic muscle activity, was unchanged in COPD patients but reduced in controls (+4.3 ± 11.6 vs. -5.5 ± 7.6%, P < 0.05). Performance fatigue as a fraction of peak incremental power was greater in COPD vs. controls and related to resting (FEV1/FVC) and peak exercise (V̇E/maximal voluntary ventilation) pulmonary function (r2 = 0.47 and 0.55, P < 0.05). COPD patients are more fatigable than controls, but this fatigue is insufficient to constrain locomotor power and define exercise intolerance.
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Affiliation(s)
- Daniel T Cannon
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California
| | - Ana Claudia Coelho
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,Department of Pulmonology, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; and
| | - Robert Cao
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Andrew Cheng
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Janos Porszasz
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Richard Casaburi
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Harry B Rossiter
- Division of Respiratory & Critical Care Physiology & Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California; .,Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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Keir DA, Copithorne DB, Hodgson MD, Pogliaghi S, Rice CL, Kowalchuk JM. The slow component of pulmonary O2 uptake accompanies peripheral muscle fatigue during high-intensity exercise. J Appl Physiol (1985) 2016; 121:493-502. [DOI: 10.1152/japplphysiol.00249.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/21/2016] [Indexed: 11/22/2022] Open
Abstract
During constant-power output (PO) exercise above lactate threshold (LT), pulmonary O2 uptake (V̇o2p) features a developing slow component (V̇o2pSC). This progressive increase in O2 cost of exercise is suggested to be related to the effects of muscle fatigue development. We hypothesized that peripheral muscle fatigue as assessed by contractile impairment would be associated with the V̇o2pSC. Eleven healthy men were recruited to perform four constant-PO tests at an intensity corresponding to ∼Δ60 (very heavy, VH) where Δ is 60% of the difference between LT and peak V̇o2p. The VH exercise was completed for each of 3, 8, 13, and 18 min (i.e., VH3, VH8, VH13, VH18) with each preceded by 3 min of cycling at 20 W. Peripheral muscle fatigue was assessed via pre- vs. postexercise measurements of quadriceps torque in response to brief trains of electrical stimulation delivered at low (10 Hz) and high (50 Hz) frequencies. During exercise, breath-by-breath V̇o2p was measured by mass spectrometry and volume turbine. The magnitude of V̇o2pSC increased ( P < 0.05) from 224 ± 81 ml/min at VH3 to 520 ± 119, 625 ± 134, and 678 ± 156 ml/min at VH8, VH13, and VH18, respectively. The ratio of the low-to-high frequency (10/50 Hz) response was reduced ( P < 0.05) at VH3 (−12 ± 9%) and further reduced ( P < 0.05) at VH8 (−25 ± 11%), VH13 (−42 ± 19%), and VH18 (−46 ± 16%), mirroring the temporal pattern of V̇o2pSC development. The reduction in 10/50 Hz ratio was correlated ( P < 0.001, r2 = 0.69) with V̇o2pSC amplitude. The temporal and quantitative association of decrements in muscle torque production and V̇o2pSC suggest a common physiological mechanism between skeletal muscle fatigue and loss of muscle efficiency.
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Affiliation(s)
- Daniel A. Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - David B. Copithorne
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Michael D. Hodgson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Silvia Pogliaghi
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Italy
| | - Charles L. Rice
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; and
| | - John M. Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
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Zoladz JA, Majerczak J, Grassi B, Szkutnik Z, Korostyński M, Gołda S, Grandys M, Jarmuszkiewicz W, Kilarski W, Karasinski J, Korzeniewski B. Mechanisms of Attenuation of Pulmonary V'O2 Slow Component in Humans after Prolonged Endurance Training. PLoS One 2016; 11:e0154135. [PMID: 27104346 PMCID: PMC4841588 DOI: 10.1371/journal.pone.0154135] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/09/2016] [Indexed: 11/19/2022] Open
Abstract
In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V'O2) kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean±SD: age 22.33±1.44 years, V'O2peak 3198±458 mL ∙ min-1) performed an endurance training composed mainly of moderate-intensity cycling, lasting 20 weeks. Training resulted in a decrease (by ~5%, P = 0.027) in V'O2 during prior low-intensity exercise (20 W) and in shortening of τp of the V'O2 on-kinetics (30.1±5.9 s vs. 25.4±1.5 s, P = 0.007) during subsequent heavy-intensity cycling. This was accompanied by a decrease of the slow component of V'O2 on-kinetics by 49% (P = 0.001) and a decrease in the end-exercise V'O2 by ~5% (P = 0.005). An increase (P = 0.02) in the vascular endothelial growth factor receptor 2 mRNA level and a tendency (P = 0.06) to higher capillary-to-fiber ratio in the vastus lateralis muscle were found after training (n = 11). No significant effect of training on the V'O2peak was found (P = 0.12). However, the power output reached at the lactate threshold increased by 19% (P = 0.01). The power output obtained at the V'O2peak increased by 14% (P = 0.003) and the time of 1,500-m performance decreased by 5% (P = 0.001). Computer modeling of the skeletal muscle bioenergetic system suggests that the training-induced decrease in the slow component of V'O2 on-kinetics found in the present study is mainly caused by two factors: an intensification of the each-step activation (ESA) of oxidative phosphorylation (OXPHOS) complexes after training and decrease in the ''additional" ATP usage rising gradually during heavy-intensity exercise.
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Affiliation(s)
- Jerzy A. Zoladz
- Department of Muscle Physiology, Chair of Physiology and Biochemistry, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland
| | - Joanna Majerczak
- Department of Muscle Physiology, Chair of Physiology and Biochemistry, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland
| | - Bruno Grassi
- Dipartimento di Scienze Mediche e Biologiche, Università degli Studi di Udine, Udine, Italy
| | - Zbigniew Szkutnik
- Faculty of Applied Mathematics, AGH-University of Science and Technology, Krakow, Poland
| | - Michał Korostyński
- Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - Sławomir Gołda
- Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - Marcin Grandys
- Department of Muscle Physiology, Chair of Physiology and Biochemistry, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland
| | - Wiesława Jarmuszkiewicz
- Department of Bioenergetics, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Wincenty Kilarski
- Department of Cell Biology and Imaging, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Janusz Karasinski
- Department of Cell Biology and Imaging, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Bernard Korzeniewski
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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48
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de Souza KM, Dekerle J, Salvador PCDN, de Lucas RD, Guglielmo LGA, Greco CC, Denadai BS. Rate of utilization of a given fraction of W' (the curvature constant of the power-duration relationship) does not affect fatigue during severe-intensity exercise. Exp Physiol 2016; 101:540-8. [PMID: 26792027 DOI: 10.1113/ep085451] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/15/2016] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the rate of utilization of W' (the curvature constant of the power-duration relationship) affect fatigue during severe-intensity exercise? What is the main finding and its importance? The magnitude of fatigue after two severe-intensity exercises designed to deplete the same fraction of W' (70%) at two different rates of utilization (fast versus slow) was similar after both exercises. Moreover, the magnitude of fatigue was related to critical power (CP), supporting the contention that CP is a key determinant in fatigue development during high-intensity exercise. Thus, the CP model is a suitable approach to investigate fatigue mechanisms during high-intensity exercise. The depletion of W' (the curvature constant of the power-duration relationship) seems to contribute to fatigue during severe-intensity exercise. Therefore, the aim of this study was to determine the effect of a fast versus a slow rate of utilization of W' on the occurrence of fatigue within the severe-intensity domain. Fifteen healthy male subjects performed tests to determine the critical power, W' and peak torque in the control condition (TCON ) and immediately after two fatiguing work rates (THREE and TEN) set to deplete 70% W' in either 3 (TTHREE ) or 10 min (TTEN ). The TTHREE and TTEN were significantly reduced (F = 19.68, P = 0.01) in comparison to TCON . However, the magnitude of reduction in peak torque (TTHREE = -19.8 ± 10.1% versus TTEN = -16.8 ± 13.3%) was the same in the two fatiguing exercises (t = -0.76, P = 0.46). There was a significant inverse relationship between the critical power and the reduction in peak torque during both THREE (r = -0.49, P = 0.03) and TEN (r = -0.62, P = 0.02). In contrast, the W' was not significantly correlated with the reduction in peak torque during both THREE (r = -0.14, P = 0.33) and TEN (r = -0.30, P = 0.10). Thus, fatigue following severe-intensity exercises performed at different rates of utilization of W' was similar when the same work was done above the critical power (i.e. same amount of W' used).
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Affiliation(s)
| | - Jeanne Dekerle
- Centre for Sport and Exercise Science and Medicine, University of Brighton, Eastbourne, UK
| | | | - Ricardo Dantas de Lucas
- Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, Florianópolis, Brazil
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49
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Keir DA, Benson AP, Love LK, Robertson TC, Rossiter HB, Kowalchuk JM. Influence of muscle metabolic heterogeneity in determining the V̇o2p kinetic response to ramp-incremental exercise. J Appl Physiol (1985) 2015; 120:503-13. [PMID: 26679614 DOI: 10.1152/japplphysiol.00804.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/15/2015] [Indexed: 10/22/2022] Open
Abstract
The pulmonary O2 uptake (V̇o2p) response to ramp-incremental (RI) exercise increases linearly with work rate (WR) after an early exponential phase, implying that a single time constant (τ) and gain (G) describe the response. However, variability in τ and G of V̇o2p kinetics to different step increments in WR is documented. We hypothesized that the "linear" V̇o2p-WR relationship during RI exercise results from the conflation between WR-dependent changes in τ and G. Nine men performed three or four repeats of RI exercise (30 W/min) and two step-incremental protocols consisting of four 60-W increments beginning from 20 W or 50 W. During testing, breath-by-breath V̇o2p was measured by mass spectrometry and volume turbine. For each individual, the V̇o2p RI response was characterized with exponential functions containing either constant or variable τ and G values. A relationship between τ and G vs. WR was determined from the step-incremental protocols to derive the variable model parameters. τ and G increased from 21 ± 5 to 98 ± 20 s and from 8.7 ± 0.6 to 12.0 ± 1.9 ml·min(-1)·W(-1) for WRs of 20-230 W, respectively, and were best described by a second-order (τ) and a first-order (G) polynomial function of WR (lowest Akaike information criterion score). The sum of squared residuals was not different (P > 0.05) when the V̇o2p RI response was characterized with either the constant or variable models, indicating that they described the response equally well. Results suggest that τ and G increase progressively with WR during RI exercise. Importantly, these relationships may conflate to produce a linear V̇o2p-WR response, emphasizing the influence of metabolic heterogeneity in determining the apparent V̇o2p-WR relationship during RI exercise.
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Affiliation(s)
- Daniel A Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada; School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Alan P Benson
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Lorenzo K Love
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada; School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Taylor C Robertson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada; School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California; and School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada; School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada;
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50
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De Ruiter CJ, Hamacher P, Wolfs BGA. A Short Submaximal Test to Determine the Fatigue Threshold of Knee Extensors in Young Men. Med Sci Sports Exerc 2015; 48:913-9. [PMID: 26656774 DOI: 10.1249/mss.0000000000000832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Recently, a fatigue threshold obtained during submaximal repetitive isometric knee extensor contractions was related to V˙O2max measured during cycling and to exercise endurance. However, test duration is quite long (20-30 min in young people) to be of practical and possibly clinical use. The purpose of the present study was to test the day-to-day reliability of a newly developed short test that assessed the fatigue threshold during a submaximal test with the knee extensors. METHODS Fifteen healthy young males were tested three times, once using the original long protocol (5-min blocks of repetitive unilateral isometric knee extensor contractions with stepwise (5% MVC) increases of force) and twice using a new shorter protocol. In the latter, force increased by 2% MVC every 30 s, starting at 15% MVC (all contractions were 3 s on, 2 s off). The fatigue threshold was defined as the force where the EMG/force ratio started to increase and, compared with the force, at which deoxygenated hemoglobin concentration ([HHb]) increased steeply (HHb threshold). RESULTS The EMG/force threshold during the short trials was reached after 3.9 ± 1.5 min of submaximal exercise and similar (P > 0.05) between days. The EMG/force threshold showed good reliability (intraclass correlation coefficient = 0.87, SEM = 2.2%) and did not differ between (P > 0.05) the short (31.1% ± 7.6% MVC) and long tests (30.5% ± 6.2% MVC), with a significant relation (r = 0.71) between both tests. Similar results (P > 0.05) were found for the HHb threshold. CONCLUSION In young healthy men, a fatigue threshold can be detected during repetitive isometric knee extensor contractions using a short submaximal test, which may be suitable for untrained or frail people and patients.
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