Wilfong, E., Frederick, M., Krings, K., & Hoover, D. (2009). Time of day does not affect measures of performance while cycling. ACSM 56th Annual Meeting, Seattle, Washington, Presentation Number 2812.

This study investigated the influence of time-of-day on measures of physiology, perceived exertion, or gross motor performance. Avid recreational cyclists (N = 14) completed three submaximal exercise bouts on two separate sessions, one session starting at 6:00 AM and the other at 6:00 PM. The trials were performed at workload (Watts) to bodyweight (kg) ratios of 1.5:1, 2.0:1, and 2.5:1. The order of the two sessions and three workloads were randomized. Potential confounding variables such as caffeine use were controlled. Dependent measures of heart rate, perceived exertion, and gross motor performance were obtained throughout each trial.

No significant differences were found for time-of-day for all dependent measures. There also were no significant differences found related to the covariate of usual training time (AM vs. PM).

Implication. Time-of-day did not significantly affect performance measures during steady state cycling.

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