Diurnal variation in Wingate-test performance and associated electromyographic parameters

Area of Science:

• Exercise Physiology
• Chronobiology
• Sports Science

Background:

• Diurnal variations in physiological functions can impact athletic performance.
• Understanding time-of-day effects on intense exercise is crucial for optimizing training and competition strategies.

Purpose of the Study:

• To investigate the influence of time of day on electromyographic (EMG) activity and performance during a 30-second Wingate cycling test.
• To determine if performance differences are related to central or peripheral neuromuscular factors.

Main Methods:

• 22 male subjects performed a 30-second Wingate test at 07:00 and 17:00 in a randomized order.
• Measured peak power, mean power, fatigue index, and power output evolution.
• Recorded surface EMG from vastus lateralis and medialis, analyzing root mean square (RMS) and mean power frequency (MPF).
• Calculated neuromuscular efficiency (NME).

Main Results:

• Performance metrics (peak power, mean power, fatigue index) were significantly higher in the evening (17:00) compared to the morning (07:00).
• Power output decreased in two phases: a rapid decline in the first 20s (higher in the evening) and a slower decline in the last 10s (time-independent).
• Neuromuscular efficiency and MPF were higher in the evening during the initial phase of the test, with no significant time-of-day differences in EMG RMS.

Conclusions:

• Wingate test performance is enhanced in the evening, likely due to superior peripheral muscle function and reduced fatigue.
• The observed diurnal variation in performance is primarily attributed to peripheral mechanisms rather than central factors.
• These findings suggest that training and competition scheduling should consider diurnal rhythms for optimal athletic outcomes.