Running the clock: new insights into exercise and circadian rhythms for optimal metabolic health

Abstract

Circadian rhythms are recurring molecular, physiological and behavioural processes that follow a near 24-h cycle, synchronized with natural transitions between day and night (Acosta-Rodriguez et al., 2021). Disruptions to the circadian system impair metabolic regulation, inflammatory responses and tissue repair, contributing to chronic diseases such as type 2 diabetes, cardiometabolic diseases and musculoskeletal disorders (Acosta-Rodriguez et al., 2021; Chaput et al., 2023). Recent research indicates that altering the timing of key behaviours – such as when we exercise, eat and sleep – leverages circadian biology to promote well-being, although the specific mechanisms are not fully understood (Acosta-Rodriguez et al., 2021; Blankenship et al., 2021; Petersen et al., 2022). An improved understanding of how the timing of behaviours such as exercise and eating interact with endogenous circadian-regulated processes could offer new insights into optimizing health interventions, improving metabolic efficiency and designing preventive strategies for chronic diseases by aligning these behaviours with natural biological rhythms. This knowledge may also help explain individual variability in response to lifestyle interventions, paving the way for more personalized strategies.

This special issue of The Journal of Physiology entitled ‘Circadian rhythms, exercise and metabolic health’ explores new insights into how exercise (and potentially the time of day that exercise is performed) influences circadian, metabolic, mitochondrial and cardiovascular functions to optimize physical performance and metabolic health, while also examining drivers of individual variability in these responses. Physical exercise has long been regarded as a powerful intervention for treating/preventing conditions such as obesity, cancer and mental health disorders, while also promoting increased healthspan (Blankenship et al., 2021). Traditionally, exercise prescription has focused on the manipulation of factors such as frequency, intensity, duration and mode (Blankenship et al., 2021). However, as emphasized in this special issue, the timing of exercise may also be strategically harnessed to enhance its benefits. Indeed, skeletal muscle mitochondrial function and physical performance follow daily rhythms, peaking at specific times of day, while disruptions to circadian alignment – such as through simulated night shift work or rapid time zone changes – impair muscle function (Blankenship et al., 2021; Chaput et al., 2023). As highlighted by the new research in this special issue, aligning exercise with optimal metabolic rhythms offers a promising approach with significant clinical and research implications, bridging the fields of sleep/circadian biology and exercise physiology.