Abstract
PURPOSE: The purpose of this study was to examine the metabolic relationship between VO2PEAK, ventilatory threshold (VT), and electromyographic fatigue threshold (EMGFT), as well as to compare the power output produced at VO2PEAK, VT, and EMGFT. METHODS: Thirty-eight college-aged males (mean ± SD = 22.5 ± 3.5 yrs) performed an incremental (25 W increase every 2 min) test to exhaustion on an electronically braked cycle ergometer (Corival, Lode) for the determination of VO2PEAK and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMGFT value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2 min work bouts (ranging from 75-325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10 second intervals and plotted over the 2 min work bout. The resulting slopes from each successive work bout were used to calculate EMGFT. RESULTS: Power outputs and VO2 values from each subject's incremental test to exhaustion were regressed and the linear equations were used to compute the VO2 value that corresponded to each fatigue threshold. Two separate one-way repeated measures ANOVAs indicated significant differences among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 ± 0.50 L/min) and EMGFTVO2 (1.84 ± 0.53) were not significantly different (p>0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 ± 37.8 W compared with 134.1 ± 43.5 W at EMGFT (p > 0.05) with a strong correlation between the two variables (r = 0.766). CONCLUSIONS: Metabolic measurements, as well as the power outputs at VT and EMGFT were strongly correlated. The significant relationship between VT and EMGFT suggest that both procedures may reflect similar physiological factors' associated with the onset of fatigue. As a result of these findings, the EMGFT test may provide an attractive alternative to estimating VT.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have