When you exercise may matter as much as how often |
Exercise advice typically covers how often, how intense, and how long you work out. A new clinical trial adds a fourth variable: the time of day.
Researchers enrolled 134 sedentary adults aged 40 to 60 years who carried at least one cardiovascular risk factor. All participants completed the same moderate aerobic sessions 5 days a week for 12 weeks. The only variable was whether they exercised during their body’s natural peak — morning for early risers, evening for night owls.
The results demonstrated a clear difference. Chronotype-aligned exercisers saw systolic blood pressure fall by nearly 11 mmHg; those who worked out against their chronotype dropped only 5.5 mmHg. LDL cholesterol fell almost twice as far in the aligned group. Sleep quality and fasting glucose also favored the aligned group.
Cardiologist Cheng-Han Chen, MD, who reviewed the findings, called it evidence that “aligning exercise with someone's internal circadian clock can potentially improve health outcomes.” A separate analysis found that chronotype-aligned timing was the single strongest predictor of blood pressure change.
One unexpected finding emerged from this research: when forced to exercise at their least preferred time, early risers still performed better than night owls on several measures. Whether this really represents an early bird advantage or is more an artifact specific to this study remains to be investigated.
For more on optimizing exercise timing for cardiovascular health, jump to “Synching workouts to natural body clock may help maximize heart health benefits.”
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