Measuring Fatigue Relative to Peak Power Output during High-Intensity Cycle Sprinting

Abstract

The purpose of this report was to introduce and validate a method to account for variable fatigue rates during cycle sprinting by incorporating decline from peak power (30%) as a test termination criterion. Fifteen healthy men performed three maximal sprint tests separated by 20 min (Bouts 1 and 2) and 48 hours (Bout 3). Power curves were analyzed for peak power, time to peak, time to fatigue (decline of 30% from peak), total work, total test time, fatigue rate, and the fatigue index. High test-retest reliability was demonstrated for all variables (R = 0.85–0.98). No significant differences were detected between variables (Bouts 1, 2 and 3; p > 0.01). Fatigue rates varied widely among participants (range = 24.7–65.4 W·s^-1), but the fatigue index was consistent (31.1 ± 0.16; mean ± standard error of measurement, range = 30.1–32.5%). Our data show that variable fatigue responses among participants are normalized to the percentage of decline from peak power by incorporating a relative fatigue cutoff criterion. This approach might inform mechanisms relating to short-term fatigue and recovery during consecutive sprint bouts.

Key Words:

• short-term power output
• on-line analysis
• constant-load ergometry