An examination of neuromuscular and metabolic fatigue thresholds

This study examined the relationships among the physical working capacity at the fatigue threshold (PWCFT), the power outputs associated with the gas exchange threshold (PGET) and the respiratory compensation point (PRCP), and critical power (CP) to identify possible physiological mechanisms underly...

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Bibliographic Details
Published in:Physiological measurement 2013-10, Vol.34 (10), p.1253-1267
Main Authors: Bergstrom, Haley C, Housh, Terry J, Cochrane, Kristen C, Jenkins, Nathaniel D M, Lewis, Robert W, Traylor, Daniel A, Zuniga, Jorge M, Schmidt, Richard J, Johnson, Glen O, Cramer, Joel T
Format: Article
Language:English
Subjects:
critical power
cycle ergometry
Electromyography
Exercise - physiology
Female
gas exchange threshold
Humans
Male
Metabolism
Muscle Fatigue - physiology
Nervous System Physiological Phenomena
physical working capacity at the fatigue threshold
Pulmonary Gas Exchange
Regression Analysis
Respiration
respiratory compensation point
Young Adult
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Summary:This study examined the relationships among the physical working capacity at the fatigue threshold (PWCFT), the power outputs associated with the gas exchange threshold (PGET) and the respiratory compensation point (PRCP), and critical power (CP) to identify possible physiological mechanisms underlying the onset of neuromuscular fatigue. Ten participants (mean ± SD age: 20 ± 1 years) performed a maximal incremental cycle ergometer test to determine the PWCFT, PGET, and PRCP. CP was determined from the 3 min all-out test. The PWCFT (197 ± 55 W), PRCP (212 ± 50 W), and CP (208 ± 63 W) were significantly greater than the PGET (168 ± 40 W), but there were no significant differences among the PWCFT, PRCP, and CP. All thresholds were significantly inter-4 (r = 0.794-0.958). The 17% greater estimates for the PWCFT than PGET were likely related to differences in the physiological mechanisms that underlie these fatigue thresholds, while the non-significant difference and high correlation between the PWCFT and the PRCP suggested that hyperkalemia may underlie both thresholds. Furthermore, it is possible that the 5% lower estimate of the PWCFT than CP could more accurately reflect the demarcation of the heavy from severe exercise intensity domains.
ISSN:0967-3334
1361-6579
DOI:10.1088/0967-3334/34/10/1253