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Diurnal Variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5 C)

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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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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