Joensahakij, Setthawut

Abstract Background: The relationships between exercise timing and health outcomes including anthropometric indices, metabolic markers, and sleep health have not been clearly established. To gain better insights, we performed the meta-analysis to determine the effects of morning versus evening exercise on various health outcomes. Methods: We collected studies from MEDLINE, EMBASE, and Cochrane databases from inception to March 2023 to perform a meta-analysis. Exercise is defined as performing activity at least moderate intensity. For the outcomes of interest, the mean differences (MD) were employed using a random-effects model, the generic inverse variance method of DerSimonian and Laird. Results: A total of 716 patients were analyzed from 14 studies including randomized controlled trial and observational studies. We found no significant associations between exercise timing and several health-related parameters. Specifically, the data showed no notable differences in body weight (MD: -0.12 kg [95% CI −0.81 to 0.58]) and BMI (MD: -0.07 kg/m2 [95% CI −0.46 to 0.32]) when comparing morning and evening exercise sessions. Similarly, sleep latency was not significantly affected by exercise timing (MD: -2.24 minutes [95% CI −5.83 to 1.35]). Furthermore, changes in metabolic biomarkers, including LDL (MD: -6.64 mg/dL [95% CI −20.08 to 6.79]) and HDL (MD: 0.09 mg/dL [95% CI 0 to 0.17]), were not significantly associated with the timing of exercise. Conclusion: This meta-analysis found no significant relationship between exercise timing and health outcomes including anthropometric indices, metabolic markers, and sleep health. While considered as hypothesis generating, timing of exercise should equally prune patients’ health outcomes.