Is there a diurnal variation in 4-km cycling time-trial performance, conducted in an environmental chamber where a standardised approach has been employed?

ABSTRACT

We investigated the hypothesis that a daily-variation exists for a 4-km time-trial, where a standardised-approach has been employed. Twenty-six male students completed a 30-s Wingate test, a $\dot{\mathrm{V}}$O₂ peak test: and then three 4-km familiarisations at 12:00 h. Two further time-trials counterbalanced for start at 07:30 or 17:30 h were undertaken. There was 72 h between each session. Heart rate, rectal and skin temperature values, rating-of-perceived-exertion, effort, pacing perception and split-times were measured every 1-km during the time-trial. Blood lactate, urine osmolarity, rectal and skin temperature were taken at rest and immediately after each time-trial. Evening finishing times, resting rectal temperatures, pre-post time-trial blood lactate were faster, higher with a greater rise (~10 s, 0.48°C, 0.7mmol.L) than morning values (p<0.05) with no other interactions. In summary, where a standardised approach has been employed 4-km performance was 2.6 % faster in the evening than the morning (ES = 0.34, power = 0.8).

KEYWORDS:

• Cycle-ergometry
• Cycle-ergometry
• rectal temperature
• design-checklist

Acknowledgements

We would like to thank the participants who participated in the study, also the research assistants who helped with data collection Mr Adrian Markov, Miss Theresa Toussaint, Mr Tom Hall-Say, Mr Samuel Dickson, Mr Dylan Gill, Mr Kyle McCann and Mr Greg Stewart-Taylor.

Disclosure statement

No potential conflict of interest was reported by the author(s).