Pullinger, S, Oska, J, Clark, L, Guyatt, JWF, Newlove, A, Burniston, JG, Doran, DA, Waterhouse, J and Edwards, B (2018) Diurnal Variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5 C). Chronobiology International, 35 (8). pp. 1054-1065. ISSN 1525-6073

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Abstract

The present study investigated whether increasing morning rectal temperatures (Trec) to evening levels, or increasing morning and evening Trec to an “optimal” level (38.5°C), resulting in increased muscle temperatures (Tm), would offset diurnal variation in repeated sprint (RS) performance in a causal manner. Twelve trained males underwent five sessions [age (mean ± SD) 21.0 ± 2.3 years, maximal oxygen consumption (V̇O2max) 60.0 ± 4.4 mL.kg–1 min–1, height 1.79 ± 0.06 m, body mass 78.2 ± 11.8 kg]. These included control morning (M, 07:30 h) and evening (E, 17:30 h) sessions (5-min warm-up), and three further sessions consisting of a warm-up morning trial (ME, in 39–40°C water) until Trec reached evening levels; two “optimal” trials in the morning and evening (M38.5 and E38.5, in 39–40°C water) respectively, until Trec reached 38.5°C. All sessions included 3 × 3-s task-specific warm-up sprints, thereafter 10 × 3-s RS with 30-s recoveries were performed a non-motorised treadmill. Trec and Tm measurements were taken at the start of the protocol and following the warm-up periods. Values for Trec and Tm at rest were higher in the evening compared to morning values (0.48°C and 0.69°C, p < 0.0005). RS performance was lower (7.8–8.3%) in the M for distance covered (DC; p = 0.002), average power (AP; p = 0.029) and average velocity (AV; p = 0.002). Increasing Trec in the morning to evening values or optimal values (38.5°C) did not increase RS performance to evening levels (p = 1.000). However, increasing Trec in the evening to “optimal” level through a passive warm-up significantly reduced DC (p = 0.008), AP (p < 0.0005) and AV (p = 0.007) to values found in the M condition (6.0–6.9%). Diurnal variation in Trec and Tm is not wholly accountable for time-of-day oscillations in RS performance on a non-motorised treadmill; the exact mechanism(s) for a causal link between central temperature and human performance are still unclear and require more research.

Item Type:	Article
Additional Information:	This is an Accepted Manuscript of an article published by Taylor & Francis in Chronobiology International on 22/03/2018, available online: http://www.tandfonline.com/10.1080/07420528.2018.1454938
Uncontrolled Keywords:	06 Biological Sciences, 11 Medical And Health Sciences
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport & Exercise Sciences
Publisher:	Taylor & Francis
Date Deposited:	28 Feb 2020 12:13
Last Modified:	04 Sep 2021 10:37
DOI or ID number:	10.1080/07420528.2018.1454938
URI:	https://researchonline.ljmu.ac.uk/id/eprint/8365

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