Timing of Exercise May Impact Health Risks for Men with Type 2 Diabetes

Exercise is often recommended to Type 2 diabetics to help manage the condition, but is there a specific time of day when it’s most beneficial to exercise? A new study aimed to find out.

Researchers from Brigham and Women’s Hospital and Joslin Diabetes Care investigators examined the link between the time Type 2 diabetics exercised at moderate-to-high intensity and their cardiovascular fitness and health risks. Their findings were published in February in Diabetes Care.

Jingyi Qian, who co-authored the study, works in the Division of Sleep and Circadian Disorders at Brigham and serves as a professor of medicine at Harvard Medical School.

He says, “The general message for our patient population remains that you should exercise whenever you can as regular exercise provides significant benefits for health. But researchers studying the effects of physical activity should take into account timing as an additional consideration so that we can give better recommendations to the general public about how time of day may affect the relationship between exercise and cardiovascular health.”


Researchers looked at 2,035 people who had taken part in the Look AHEAD (Action for Health in Diabetes) study, which began in 2001 and included more than 5,000 people with diabetes and who were overweight or obese. The participants had worn accelerometers on their hips for one week, which researchers used to determine when they had exercised or done labor-intensive work. Then, to determine participants’ risk of developing coronary heart disease over the next four years, they used the Framingham risk score algorithm. The algorithm was created in 1998 and considers different combinations of factors before gauging someone’s ten-year risk of developing coronary heart disease.

The study found that men who exercised in the morning had the highest risk of developing CHD regardless of how much or how hard they exercised. Men most active at midday, meanwhile, had lower cardiorespiratory fitness levels. Women studied didn’t appear to have a strong link between the time of activity and their risk of CHD or their fitness levels.


Researchers say existing differences between the sexes may play a role here because men tend to be more at risk of CHD at a younger age, but there could be other contributing factors. They also say it’s still unknown why these time tables may impact health risks and fitness. Qian says they’re looking forward to using more data to explain that link.

Another limitation of the study is that circadian rhythms couldn’t be taken into consideration. Someone who wakes up later may feel like an evening workout is a midday workout. Qian says that could be further investigated in future studies.

He explains, “Interest in the interaction between physical activity and the circadian system is still just emerging. We formed a methodology for quantifying and characterizing participants based on the clock-time of their physical activity, which allows researchers to carry out other studies on other cohorts.”

To read more about the study, click here.

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