Chronotype-aligned exercise timing in middle-aged adults at cardiometabolic risk: a randomised controlled trial.

OBJECTIVE

To investigate whether aligning exercise timing with chronotype enhances cardiometabolic and sleep-related benefits in sedentary adults with cardiovascular risk factors.

METHODS

In this 12-week randomised controlled trial conducted in Lahore, Pakistan (January-June 2025), 150 sedentary adults (aged 40-60) with at least one cardiovascular risk factor were recruited and categorised as morning-type or evening-type using the Morningness-Eveningness Questionnaire and validated by 48 hour core body temperature monitoring. Participants were randomised into a chronotype-aligned exercise (CAE) group exercising at their preferred time, or a chronotype-misaligned exercise (CME) group exercising at their non-preferred time. Moderate-intensity aerobic training (5 sessions/week, 40 min/session) was supervised. Primary outcomes included systolic and diastolic blood pressure (BP) and heart rate variability (RMSSD); secondary outcomes included peak oxygen consumption (VO₂ peak), low density lipoprotein (LDL), fasting glucose and sleep quality (PSQI), assessed pre- and post-intervention.

RESULTS

Of 150 randomised participants, 134 completed the study (CAE: n=64; CME: n=70). CAE led to significantly greater improvements in systolic BP (-10.8 vs -5.5 mm Hg, p=0.002), diastolic BP, RMSSD, VO₂ peak, LDL, fasting glucose and PSQI scores compared with CME. Repeated measures analysis of variance (ANOVA) revealed significant group×time interactions across all outcomes (eg, systolic BP: η²=0.095, p=0.005). The reduction in systolic BP in the CAE group was substantial and significantly greater than in the CME group.

CONCLUSION

Aligning exercise timing with individual chronotype significantly enhances cardiometabolic and sleep-related outcomes in at-risk adults. Chronotype-based exercise prescriptions may offer a cost-effective, personalised approach to improving cardiovascular health.