The effect of diurnal variation on the performance of exhaustive continuous and alternated-intensity cycling exercises

Abstract

The purpose of this study was to explore the effect of time of day (TD) on two types of exercise protocols [continuous (CP) versus alternated (AP)]. Eleven physical education students (mean ± SD: age = 24.4 ± 1.2 years, aerobic peak power (APP) = 290 ± 31.9 W) underwent four sessions. These sessions were performed at 08:00 (AM) and 18:00 (PM) and consisted of cycling exercises until voluntary exhaustion at 90% APP (CP) or 70%-105% APP (AP) with the order of testing randomly assigned. Time to exhaustion (time limit = Tlim) was measured from the start of the test to when voluntary exhaustion occurred. Heart rate (HR) was recorded at baseline (HRbaseline) and throughout the protocols to determine HR at exhaustion (HRpeak). Blood lactate ([La]) was measured at rest, immediately after exhaustion and at 2min30 post-exercise to determine [La]peak. A significantly higher means of Tlim (334 ± 57 s; 272 ± 59 s; p< 0.05), HRbaseline (72 ± 5 beats/min; 67 ± 5 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 178 ± 9 beats/min; p< 0.01) and [La]peak (16.2 ± 2.1 mmol/l; 13.9 ± 1.9 mmol/l; p< 0.05) were observed in CP at the PM compared to the AM. In addition, a significant higher means of Tlim (380 ± 54 s; 312 ± 82 s; p< 0.05), HRbaseline (73.1 ± 5.5 beats/min; 67 ± 5.4 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 180 ± 9 beats/min; p< 0.05) and [La]peak (17.9 ± 1.8 mmol/l; 14.7 ± 2.1 mmol/l; p< 0.01) were observed in AP at the PM compared to the AM. It is concluded that AP and CP are more appropriate in the late afternoon than in the morning for performing long-lasting exercises. The AP could be a novel strategy for increasing the engagement in physical activity.

Impact of time-of-day on judo-specific performance

“…Athletes' SJFT performances and physiological outputs did not differ at different times of the day. Similar findings were suggested by previous studies (Deschenes et al, 1998;Souissi et al, 2020). There are conflicting findings related to effect of time-of-day on RPE.…”

“…In another study applied to soccer players, although peak anaerobic power was found higher in the afternoon compared to morning and evening, the changes in bLA was found similar (Ünver & Atan, 2021). It was stated that the different times of the day did not affect bLA before exercise but peak bLA was higher in the evening compared to morning in line with the increase in the exercise performance following the exhaustive exercises (Souissi et 2020). The effect of the time-of-day on the changes in exercise performance and bLA was not compatible.…”

The Effect of Daytime Ingestion of Melatonin on Thyroid Hormones Responses to Acute Submaximal Exercise in Healthy Active Males: A Pilot Study

“…Exercise is performed at 23°C ± 0.1°C (60% ± 3% humidity). All conditions were performed indoors at the same time of the day (i.e., between 8:00 and 10:35) to minimize the effects of diurnal variations in the aerobic and anaerobic contributions to physical performance ( Dergaa, Varma, et al, 2021 ; Souissi et al, 2020 ). Figure 1 illustrates the study design.…”

Effects of eight weeks of mat pilates training on selected hematological parameters and plasma volume variations in healthy active women

“…All tests were completed within two weeks, both before- and after- PT in thermoneutral condition [ 24 , 25 ] . All sessions were performed at the same time of the day to minimize the effects of diurnal variation in the measured parameters [ 26 ] . Fig 1 outlines the study protocol.…”