TY - JOUR
T1 - An examination of neuromuscular and metabolic fatigue thresholds
AU - Bergstrom, Haley C.
AU - Housh, Terry J.
AU - Cochrane, Kristen C.
AU - Jenkins, Nathaniel D.M.
AU - Lewis, Robert W.
AU - Traylor, Daniel A.
AU - Zuniga, Jorge M.
AU - Schmidt, Richard J.
AU - Johnson, Glen O.
AU - Cramer, Joel T.
PY - 2013/10
Y1 - 2013/10
N2 - 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.
AB - 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.
KW - critical power
KW - cycle ergometry
KW - gas exchange threshold
KW - physical working capacity at the fatigue threshold
KW - respiratory compensation point
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U2 - 10.1088/0967-3334/34/10/1253
DO - 10.1088/0967-3334/34/10/1253
M3 - Article
C2 - 24021781
AN - SCOPUS:84885462431
SN - 0967-3334
VL - 34
SP - 1253
EP - 1267
JO - Physiological Measurement
JF - Physiological Measurement
IS - 10
ER -