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

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 (V̇O 2 ), carbon dioxide production (V̇CO 2 ) 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). V̇O 2 , [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 V̇O 2 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.

Morning Exercise Reduces Abdominal Fat and Blood Pressure in Women; Evening Exercise Increases Muscular Performance in Women and Lowers Blood Pressure in Men

“…Moreover, such exercise regimens, encompassing multiple energy systems, movement patterns, and athletic range also have support under an evolutionary lens ( Longman et al, 2020 ). Yet, recent research examining ETOD has focused on just one mode or a combination of resistance and endurance (aerobic) exercise regimens ( Küüsmaa-Schildt et al, 2017 ; Blazer et al, 2021 ; Creasy et al, 2022 ; Souissi et al, 2022 ). Therefore, the current body of ETOD literature lacks critical data on the typical manner in which most athletes and fitness enthusiasts engage in physical activity programs.…”

Diurnal variation of fat oxidation rate and energy expenditure in an acute bout of endurance exercise by young healthy males

“…Souissi et al . [ 23 ] involved 12 young, normal BMI and physically trained individuals in self-paced endurance cycling and reported that the RER was insignificantly lower during the evening (17:00–18:00) than in the morning (7:00–8:00). The timing of the meal and the gender of the subjects were not specified.…”

“…Souissi et al . [ 23 ] reported that the evening session caused significantly higher oxygen consumption than the morning exercise session. Ezagouri et al .…”

Daytime fluctuations of endurance performance in young soccer players: a randomized cross-over trial

“…According to the literature, we hypothesized that ( i ) endurance running performance during the 3.000-m run and the treadmill test would be higher in the evening than in the morning [ 7 , 12 , 14 , 15 ] and ( ii ) that both blood lactate levels and HR during the incremental treadmill test would be different between the morning and evening [ 4 , 16 – 21 ].…”