Timing is everything.
In recent years, scientists have gained deeper insights into how the body’s circadian rhythm—the internal 24-hour biological clock—affects overall health. Disruptions to this natural sleep-wake cycle have been linked to impairments in cognitive function and increased risks for conditions such as heart disease, type 2 diabetes, obesity, depression, and certain cancers.
The circadian rhythm not only controls when we sleep and wake but also influences daily behaviors like meal times, work schedules, and physical activity. Research has shown that this internal clock can affect exercise performance and recovery, as well as regulate body temperature and hormone levels, all of which impact physical fitness.
A recent study published in Medicine & Science in Sports and Exercise highlights a new angle: exercising at consistent times each day may benefit cardiovascular and lung health in older adults. The study involved about 800 participants, averaging 76 years old, who wore wrist accelerometers to track daily activity and underwent tests to evaluate their heart and lung function.
Lead researcher Dr. Karyn Esser explained that better cardiorespiratory fitness—how well the heart, lungs, and muscles work together—is linked to longer life and lower mortality. The study also measured walking efficiency, an indicator of healthy aging that reflects how effectively the body uses energy during walking. Results showed that individuals who were most active earlier in the day and maintained consistent daily activity times had improved fitness and walking efficiency, regardless of the total amount of exercise performed.
Dr. Esser emphasized that the timing and regularity of activity appear to work alongside the body’s natural circadian rhythm to promote health. This suggests that not just exercise itself, but when and how consistently it is done, can play a crucial role in aging well. The research team plans to continue exploring how daily activity patterns relate to other health factors such as sleep, mental health, and cognitive function. Interventional cardiologist Dr. Cheng-Han Chen also noted that these findings could eventually help tailor exercise recommendations to maximize health benefits, especially as populations age and the need for effective health strategies grows.
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