Late-afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and blood lipid levels

Abstract

BackgroundGlucose and lipid tolerance reportedly exhibit diurnal variations, being lower in the evening than in the morning. Therefore, the effects of exercise on glucose and blood lipid levels at different times of the day may differ. This study aimed to investigate the effects of short-term endurance exercise intervention in the morning versus late afternoon on 24-h blood glucose variability and blood lipid levels.MethodsTwelve healthy young men participated in a randomized crossover trial. The participants were assigned to morning (09:00–11:00) or late afternoon (16:00–18:00) endurance exercise for a week, consisting of supervised exercise sessions on Mondays, Wednesdays, and Fridays. In the morning and evening trials, the participants walked for 60 min on a treadmill at approximately 60% of maximal oxygen uptake (VO2max). Following a 2-week wash-out period, the participants performed the exercise training regimen at another time point. Continuous glucose monitoring was used to evaluate blood glucose fluctuations during each 24-h trial period. Blood samples were collected before and after each intervention to examine blood lipid and hormonal responses.ResultsExamination of the area under the curve (AUC) of the glucose level changes for 24 h after the late afternoon versus morning exercise intervention revealed significantly lower values for the former versus the latter (P < 0.01). The AUC of glucose level changes after each meal was also lower after the late afternoon versus morning intervention, and significantly lower values were observed in the late afternoon versus morning trial for breakfast and dinner (P < 0.05, P < 0.01). In addition, a significant decrease in triglycerides (TG) and TG/high-density lipoprotein cholesterol (HDL-C) was noted after versus before the late afternoon intervention (P < 0.05).ConclusionsThese results suggest that late afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and triglyceride levels.

Chrono-exercise: Time-of-day-dependent physiological responses to exercise

“…Recently, several previous studies in humans have examined the effects of different exercise timings on blood glucose levels and insulin sensitivity and have shown that evening exercise is more effective than morning exercise in improving blood glucose control and insulin sensitivity. 58 , 59 , 60 , 61 By contrast, a previous study in patients with type 1 diabetes reported that morning exercise lowers the risk of delayed hypoglycemia occurring later in the evening and improves metabolic control on the following day compared with evening exercise. 62 These findings suggest that the effects of exercise timing on the prevention and improvement of diabetes may vary depending on the type and presence of diabetes.…”

Trajectories of 24-Hour Physical Activity Distribution and Relationship with Dyslipidemia

“…This finding suggests that more specific potential grouping involving time (morning and afternoon) in a population with similar levels of physical activity might be associated with lipid metabolism, and exercising in the late afternoon might be more beneficial for the HCL-C level than exercising in the morning. Similar to this finding, a randomized crossover trial suggested that late afternoon endurance exercise was more effective than morning exercise for at improving 24-h TG/HDL-C levels [ 35 ].…”

Time-Dependent Effects of Physical Activity on Cardiovascular Risk Factors in Adults: A Systematic Review

“…Nonetheless, both Bohumila et al [ 31 ] and Chiang et al [ 30 ] found that AE/EE was more helpful for blood sugar control in different subjects, which may be caused by the differences in the muscle use patterns and molecular signaling between the two training methods. Four studies did not report any significant changes from the baseline [ 31 , 34 , 35 , 37 ] due to the large heterogeneity of the exercise intensity, period, and the time interval between the exercise and the previous meal between the studies, therefore, it is difficult to explain the difference between the results. In addition, the authors suggested that a standardized diet may result in a reduced energy intake, which in turn led to lower blood sugar levels in the subjects.…”

“…Four studies comprising 331 subjects examined the effect of ME vs. AE/EE on blood lipids in adults. A non-RCT showed that significant interactions existed for TG (96.2 ± 13.5 vs. 129.8 ± 7.9, mg/dL) and the HDL-C (60.9 ± 4.9 vs. 53.9± 3.1, mg/dL) indexes in the AE group, while there were no significant differences in the other indexes of lipid metabolism between and within the groups [ 35 ]. Bohumila et al [ 31 ] conducted a 12-week resistance training and found that ME significantly increased TG (1.6 ± 0.4 vs. 1.4 ± 0.5, mmol/L) in healthy older women, whereas EE reduced it (1.3 ± 0.7 vs. 1.7 ± 1.0, mmol/L).…”

“…In terms of blood glucose, four of the studies did not report significant changes from the baseline [ 31 , 34 , 35 , 37 ]. Among the rest studies, Matthew et al [ 36 ] divided healthy older women into ME, EE, and CON groups, and the intervention groups accepted resistance training for 12 weeks; the results of this study showed that both the ME and EE groups significantly improved the blood glucose levels of the subjects, and the decrease was more pronounced in the EE group (−4 ± 6% vs. −8 ± 10%, mmol/L).…”