Estimated times to exhaustion at the PWC V O2, PWC HRT, and VT.
The purpose of this study was to validate the Physical Working Capacity at the Heart Rate Threshold (PWC HRT) and Physical Working Capacity at the Oxygen Consumption Threshold (PWC V O2) tests by 1) using individual power vs. duration relationships to estimate the times to exhaustion (ETTE) at the PWC HRT and PWC V O2, and 2) comparing the power outputs and ETTE values of the PWC HRT and PWC V O2 with those of the ventilatory threshold (VT). Ten adults (mean age +/- SD = 23 +/- 1 years) performed an incremental test to exhaustion on a cycle ergometer for the determination of V O2 peak and VT. The subjects also performed four randomly ordered workbouts to exhaustion at different power outputs (ranging from 98 to 246 W) to determine the PWC V O2, PWC HRT, and power vs. duration relationship. Power curve analyses (y = ax b) were used to define the hyperbolic power vs. duration relationship for each subject and to determine the ETTE at the PWC V O2, PWC HRT, and VT. Two separate one-way repeated-measures analyses of variance indicated that there were significant differences among the fatigue thresholds (PWC V O2 > PWC HRT) and ETTE values (PWC HRT > PWC V O2): PWC V O2 (mean +/- SD = 147 +/- 43 W; ETTE = 21 +/- 3 minutes), PWCHRT (136 +/- 37 W; ETTE = 29 +/- 6 minutes), and VT (143 +/- 44 W; ETTE = 27 +/- 11 minutes). These findings were consistent with previous studies that indicated that the PWC HRT occurred at a lower power output than the PWC V O2. Furthermore, the PWC HRT was maintained for a mean of 29 minutes, whereas the PWC V O2 and VT were maintained for 21 and 27 minutes, respectively. These findings indicate that the ETTE values for the PWC V O2 and PWC HRT were substantially less than those suggested in previous studies.
Mielke
Michelle
M
Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska, USA. mmielke@unlserve.unl.edu
Housh
Terry J
TJ
Malek
Moh H
MH
Beck
Travis W
TW
Hendrix
C Russell
CR
Schmidt
Richard J
RJ
Johnson
Glen O
GO
D000328:Adult; D000704:Analysis of Variance; D005080:Exercise Test / Q000379:methods*; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008954:Models, Biological; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D015203:Reproducibility of Results