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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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Fenuta AM, Drouin PJ, Kohoko ZIN, Lynn MJT, Tschakovsky ME. Does a single bout maximal effort forearm exercise test for determining critical impulse result in maximal oxygen delivery and consumption in men? A randomized crossover trial. Appl Physiol Nutr Metab 2023; 48:293-306. [PMID: 36645882 DOI: 10.1139/apnm-2022-0317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In a single bout maximal effort isometric forearm handgrip exercise test (maximal effort exercise test, MXT), contraction impulse exhibits exponential decay to an asymptote equivalent to critical impulse (CI). It is unknown whether oxygen delivery (O2del) and consumption (V˙O2) achieved at CI are maximal. Healthy men participated in a randomized crossover trial at Queen's University (Kingston, ON) between October 2017-May 2018. Participants completed an MXT and forearm incremental exercise test to limit of tolerance (IET-LOT) (7 completed MXT followed by IET-LOT vs. 4 completed IET-LOT followed by MXT) within a 2 week period. Data are presented as mean ± standard deviation. Maximal forearm blood flow (FBF) and O2del were not different in 11 men (21 ± 2.5 years) between MXT and IET-LOT (FBF = 473.8 ± 132.2 mL/min vs. 502.3 ± 152.3 mL/min; P = 0.482, ηp2 = 0.015; O2del = 85.2 ± 23.5 mL/min vs. 92.2 ± 37.0 mL/min; P = 0.456, ηp2 = 0.012). However, MXT resulted in greater maximal V˙O2 than IET-LOT (44.5 ± 15.2 mL/min > 36.8 ± 11.4 mL/min; P = 0.007, ηp2 = 0.09), due to greater oxygen extraction (54.0 ± 10.0% > 44.4 ± 8.6%; P = 0.021, ηp2 = 0.185). As CI was 88.6 ± 8.2% of IET-LOT contraction impulse, maximal O2 cost of contractions in MXT was greater than IET-LOT (0.45 ± 0.14 mL/min/Ns > 0.33 ± 0.09 mL/min/Ns; P < 0.001, ηp2 = 0.166). In healthy men, MXT identifying CI results in similar peak oxygen delivery but greater peak V˙O2 via increased extraction compared to an IET-LOT, indicating increased oxygen cost. MXT-CI may better estimate maximal V˙O2 than traditional IET-LOT for this exercise modality.
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Affiliation(s)
- Alyssa M Fenuta
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Patrick J Drouin
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Zach I N Kohoko
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Mytchel J T Lynn
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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Determining Validity of Critical Power Estimated Using a Three-Minute All-Out Test in Hot Environments. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18179193. [PMID: 34501781 PMCID: PMC8431074 DOI: 10.3390/ijerph18179193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 11/21/2022]
Abstract
The aim of this study was to investigate the effects of heat on the validity of end-test power (EP) derived from a 3-min all-out test (3MT), which is considered as an alternative method for determining the conventional critical power. Twelve male cyclists were required to perform incremental exercise tests (IET) and 3MTs in both high temperature (HT; 35 °C) and thermoneutral temperature (NT; 22 °C) environments. Maximal oxygen uptake (VO2max), and first and second ventilatory thresholds (VT1 and VT2, respectively) against the power output (wVO2max, wVT1, and wVT2) were measured during IETs. EP was recorded during the 3MTs. A significant correlation was observed between wVT2 and EP under NT (r = 0.674, p < 0.05) and under HT (r = 0.672, p < 0.05). However, wVO2max, wVT1, wVT2, and EP were significantly higher in NT than in HT (p < 0.05). In conclusion, although the physiological stress induced by HT might impair exercise performance, the EP derived from 3MT can validly estimate wVT2 under HT conditions.
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Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A. The maximal metabolic steady state: redefining the 'gold standard'. Physiol Rep 2019; 7:e14098. [PMID: 31124324 PMCID: PMC6533178 DOI: 10.14814/phy2.14098] [Citation(s) in RCA: 148] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/25/2019] [Accepted: 04/27/2019] [Indexed: 02/06/2023] Open
Abstract
The maximal lactate steady state (MLSS) and the critical power (CP) are two widely used indices of the highest oxidative metabolic rate that can be sustained during continuous exercise and are often considered to be synonymous. However, while perhaps having similarities in principle, methodological differences in the assessment of these parameters typically result in MLSS occurring at a somewhat lower power output or running speed and exercise at CP being sustainable for no more than approximately 20-30 min. This has led to the view that CP overestimates the 'actual' maximal metabolic steady state and that MLSS should be considered the 'gold standard' metric for the evaluation of endurance exercise capacity. In this article we will present evidence consistent with the contrary conclusion: i.e., that (1) as presently defined, MLSS naturally underestimates the actual maximal metabolic steady state; and (2) CP alone represents the boundary between discrete exercise intensity domains within which the dynamic cardiorespiratory and muscle metabolic responses to exercise differ profoundly. While both MLSS and CP may have relevance for athletic training and performance, we urge that the distinction between the two concepts/metrics be better appreciated and that comparisons between MLSS and CP, undertaken in the mistaken belief that they are theoretically synonymous, is discontinued. CP represents the genuine boundary separating exercise in which physiological homeostasis can be maintained from exercise in which it cannot, and should be considered the gold standard when the goal is to determine the maximal metabolic steady state.
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Affiliation(s)
- Andrew M. Jones
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
| | - Mark Burnley
- School of Sport and Exercise SciencesUniversity of KentMedwayUnited Kingdom
| | - Matthew I. Black
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
| | - David C. Poole
- Department of KinesiologyKansas State UniversityManhattanKansas
| | - Anni Vanhatalo
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
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Muniz-Pumares D, Karsten B, Triska C, Glaister M. Methodological Approaches and Related Challenges Associated With the Determination of Critical Power and Curvature Constant. J Strength Cond Res 2019; 33:584-596. [DOI: 10.1519/jsc.0000000000002977] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Armstrong N. Top 10 Research Questions Related to Youth Aerobic Fitness. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2017; 88:130-148. [PMID: 28402178 DOI: 10.1080/02701367.2017.1303298] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Peak oxygen uptake ([Formula: see text]2) is internationally recognized as the criterion measure of youth aerobic fitness, but despite pediatric data being available for almost 80 years, its measurement and interpretation in relation to growth, maturation, and health remain controversial. The trainability of youth aerobic fitness continues to be hotly debated, and causal mechanisms of training-induced changes and their modulation by chronological age, biological maturation, and sex are still to be resolved. The daily physical activity of youth is characterized by intermittent bouts and rapid changes in intensity, but physical activity of the intensity and duration required to determine peak [Formula: see text]2 is rarely (if ever) experienced by most youth. In this context, it may therefore be the transient kinetics of pulmonary [Formula: see text]2 that best reflect youth aerobic fitness. There are remarkably few rigorous studies of youth pulmonary [Formula: see text]2 kinetics at the onset of exercise in different intensity domains, and the influence of chronological age, biological maturation, and sex during step changes in exercise intensity are not confidently documented. Understanding the trainability of the parameters of youth pulmonary [Formula: see text]2 kinetics is primarily based on a few comparative studies of athletes and nonathletes. The underlying mechanisms of changes due to training require further exploration. The aims of the present article are therefore to provide a brief overview of aerobic fitness during growth and maturation, increase awareness of current controversies in its assessment and interpretation, identify gaps in knowledge, raise 10 relevant research questions, and indicate potential areas for future research.
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Karsten B, Hopker J, Jobson SA, Baker J, Petrigna L, Klose A, Beedie C. Comparison of inter-trial recovery times for the determination of critical power and W' in cycling. J Sports Sci 2016; 35:1420-1425. [PMID: 27531664 DOI: 10.1080/02640414.2016.1215500] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Critical Power (CP) and W' are often determined using multi-day testing protocols. To investigate this cumbersome testing method, the purpose of this study was to compare the differences between the conventional use of a 24-h inter-trial recovery time with those of 3 h and 30 min for the determination of CP and W'. METHODS 9 moderately trained cyclists performed an incremental test to exhaustion to establish the power output associated with the maximum oxygen uptake (p[Formula: see text]max), and 3 protocols requiring time-to-exhaustion trials at a constant work-rate performed at 80%, 100% and 105% of p[Formula: see text]max. Design: Protocol A utilised 24-h inter-trial recovery (CP24/W'24), protocol B utilised 3-h inter-trial recovery (CP3/W'3), and protocol C used 30-min inter-trial recovery period (CP0.5/W'0.5). CP and W' were calculated using the inverse time (1/t) versus power (P) relation (P = W'(1/t) + CP). RESULTS 95% Limits of Agreement between protocol A and B were -9 to 15 W; -7.4 to 7.8 kJ (CP/W') and between protocol A and protocol C they were -27 to 22 W; -7.2 to 15.1 kJ (CP/W'). Compared to criterion protocol A, the average prediction error of protocol B was 2.5% (CP) and 25.6% (W'), whilst for protocol C it was 3.7% (CP) and 32.9% (W'). CONCLUSION 3-h and 30-min inter-trial recovery time protocols provide valid methods of determining CP but not W' in cycling.
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Affiliation(s)
- Bettina Karsten
- a Department of Life and Sport Science , University of Greenwich , Kent , UK
| | - James Hopker
- b School of Sport and Exercise Sciences , University of Kent , Kent , UK
| | - Simon A Jobson
- c Department of Sport & Exercise , University of Winchester , Hampshire , UK
| | - Jonathan Baker
- d Department of Sport and Exercise Science , Aberystwyth University , Wales , UK
| | - Luca Petrigna
- a Department of Life and Sport Science , University of Greenwich , Kent , UK
| | - Andreas Klose
- e Westfälische Wilhelms-Universität Münster , Arbeitsbereich für Sportpädagogik , Münster , Germany
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Waldron M, Gray A, Furlan N, Murphy A. Predicting the Sprint Performance of Adolescent Track Cyclists Using the 3-Minute All-out Test. J Strength Cond Res 2015; 30:2299-306. [PMID: 26694504 DOI: 10.1519/jsc.0000000000001311] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Waldron, M, Gray, A, Furlan, N, and Murphy, A. Predicting the sprint performance of adolescent track cyclists using the 3-minute all-out test. J Strength Cond Res 30(8): 2299-2306, 2016-This study aimed to predict 500-m time trial (TT) and 2,000-m pursuit speed of adolescent cyclists (age range = 13-15 years) using mechanical parameters derived from a critical power (CP) test and anthropometric variables. Ten well-trained competitive cyclists were assessed for body composition, body mass, stature, and frontal surface area (FSA), as well as completing the CP test. The personal best speed (km·h) of each rider during competition in 500-m TT and 2,000-m pursuit races was predicted based on the CP test data and anthropometric profiles using multiple regression analysis. A combination of the CP·FSA and internal (predicted) to external work ratio performed by the cyclists (Wint:Wext) predicted 500-m TT speed (R = 0.97; standard error of the estimate (SEE) = 0.82, P ≤ 0.001), whereas a combination of mean power·FSA (mean power) and body fat percentage predicted 2,000-m pursuit speed (R = 0.90; SEE = 1.5, p < 0.001). Between 90 and 97% of the variance in the sprint performance of adolescent cyclists can be explained by mechanical and anthropometric parameters, derived from a single visit to the laboratory. The tests and equations provided can be adopted by coaches to predict performance and set appropriate training intensities.
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Affiliation(s)
- Mark Waldron
- 1School of Sport, Health and Applied Science, St Mary's University, Twickenham, United Kingdom; and 2Department of Exercise and Sport Science, School of Science and Technology, University of New England, Armidale, Australia
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Reliability of the Single-Visit Field Test of Critical Speed in Trained and Untrained Adolescents. Sports (Basel) 2015. [DOI: 10.3390/sports3040358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Williams CA, Saynor ZL, Tomlinson OW, Barker AR. Cystic fibrosis and physiological responses to exercise. Expert Rev Respir Med 2014; 8:751-62. [DOI: 10.1586/17476348.2014.966693] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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A ‘ramp-sprint’ protocol to characterise indices of aerobic function and exercise intensity domains in a single laboratory test. Eur J Appl Physiol 2014; 114:1863-74. [DOI: 10.1007/s00421-014-2908-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 05/07/2014] [Indexed: 10/25/2022]
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Barker AR, Trebilcock E, Breese B, Jones AM, Armstrong N. The effect of priming exercise on O2 uptake kinetics, muscle O2 delivery and utilization, muscle activity, and exercise tolerance in boys. Appl Physiol Nutr Metab 2013; 39:308-17. [PMID: 24552371 DOI: 10.1139/apnm-2013-0174] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study used priming exercise in young boys to investigate (i) how muscle oxygen delivery and oxygen utilization, and muscle activity modulate oxygen uptake kinetics during exercise; and (ii) whether the accelerated oxygen uptake kinetics following priming exercise can improve exercise tolerance. Seven boys that were aged 11.3 ± 1.6 years completed either a single bout (bout 1) or repeated bouts with 6 min of recovery (bout 2) of very heavy-intensity cycling exercise. During the tests oxygen uptake, muscle oxygenation, muscle electrical activity and exercise tolerance were measured. Priming exercise most likely shortened the oxygen uptake mean response time (change, ±90% confidence limits; -8.0 s, ±3.0), possibly increased the phase II oxygen uptake amplitude (0.11 L·min(-1), ±0.09) and very likely reduced the oxygen uptake slow component amplitude (-0.08 L·min(-1), ±0.07). Priming resulted in a likely reduction in integrated electromyography (-24% baseline, ±21% and -25% baseline, ±19) and a very likely reduction in Δ deoxyhaemoglobin/Δoxygen uptake (-0.16, ±0.11 and -0.09, ±0.05) over the phase II and slow component portions of the oxygen uptake response, respectively. A correlation was present between the change in tissue oxygenation index during bout 2 and the change in the phase II (r = -0.72, likely negative) and slow component (r = 0.72, likely positive) oxygen uptake amplitudes following priming exercise, but not for muscle activity. Exercise tolerance was likely reduced (change -177 s, ±180) following priming exercise. The altered phase II and slow component oxygen uptake amplitudes in boys following priming exercise are linked to an improved localised matching of muscle oxygen delivery to oxygen uptake and not muscle electrical activity. Despite more rapid oxygen uptake kinetics following priming exercise, exercise tolerance was not enhanced.
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Affiliation(s)
- Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, Exeter EX1 2LU, UK
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