Higher evening metabolic responses contribute to diurnal variation of self-paced cycling performance

Wajdi Souissi; Omar Hammouda; Achraf Ammar; Mohamed Ayachi; Yasmine Bardiaa; Omayma Daoud; Imen Ben Hassen; Mohamed Souissi; Tarak Driss

doi:10.5114/biolsport.2021.102930

Higher evening metabolic responses contribute to diurnal variation of self-paced cycling performance

Biol Sport. 2022 Jan;39(1):3-9. doi: 10.5114/biolsport.2021.102930. Epub 2021 Feb 19.

Authors

Wajdi Souissi¹, Omar Hammouda^{1

2}, Achraf Ammar^{1

3}, Mohamed Ayachi¹, Yasmine Bardiaa⁴, Omayma Daoud⁴, Imen Ben Hassen², Mohamed Souissi⁴, Tarak Driss¹

Affiliations

¹ Interdisciplinary Laboratory in Neurosciences, Physiology and Psychology: Physical activity, Health and learning (LINP2), UFR STAPS, UPL, Paris Nanterre University, Nanterre, France.
² Research Laboratory, Molecular Bases of Human Pathology, UR19ES13, Faculty of Medicine, University of Sfax, Tunisia.
³ Institute of Sport Science, Otto-von-Guericke University, Magdeburg, Germany.
⁴ Research Laboratory "Education, Motricity, Sport and Health", High Institute of Sport and Physical Education, University of Sfax, Tunisia.

Abstract

This study examined the effect of time of day (TOD) on physical performance, and physiological and perceptual responses to a 10-km cycling time trial (TT_10km). Twelve physically trained subjects (20.3 ± 1.2 years, 74.3 ± 7.4 kg, 179.7 ± 5.5 cm) completed, in a randomized order, a TT_10km in the morning and in the evening. Intra-aural temperature (IAT) was measured at rest and following the TT_10km. Completion time, power output (PO), rating of perceived exertion (RPE), heart rate (HR), minute ventilation (V̇E), oxygen uptake (V̇O₂), carbon dioxide production (V̇CO₂) and respiratory exchange ratio (RER) were assessed every km during the TT_10km. Blood lactate concentration [La] and blood glucose concentration [Glu] were assessed before, during and immediately after the TT_10km. Faster completion time (Δ = 15.0s, p = 0.03) and higher IAT (Δ = 0.33°C, p = 0.02 for pre-TT_10km) were obtained in the evening compared to the morning with a significant correlation between Δ completion time and Δ IAT at post-TT_{10 km} (r = -0.83, p = 0.04). V̇O₂, [La] and [Glu] increased significantly during both test sessions (p < 0.001) with higher values in the evening compared to the morning (p = 0.015, p = 0.04, p = 0.01, respectively). However, the remaining parameters were found to be only affected by the TT_10km (p < 0.001). The TT_10km generates a higher V̇O₂ and higher [La] and [Glu] responses, contributing to a better cycling performance in the evening compared to the morning. The similar magnitude of the TOD effect on completion time and IAT at post-TT_10km confirms that core temperature is one of the underlying factors contributing to the diurnal variation in physical performance.

Keywords: Perceived exertion; Performance; Self-paced exercise; Sport; Time of day.