When Men Exercise Could Influence Risk of Cardiovascular Disease, Study Finds

Jingyi Qian, PhD

New research from investigators at Brigham and Women’s Hospital suggests there could between timing of physical activity and cardiovascular risk of men with type 2 diabetes.

While results indicate physical activity at any time was beneficial for reducing cardiovascular risk, investigators purport results provide evidence that exercising at a certain point during the day could provide additional benefit for a patient’s cardiovascular health, but note these effects were not seen in women.

"The general message for our patient population remains that you should exercise whenever you can as regular exercise provides significant benefits for health," said study investigator Jingyi Qian, PhD, of the Division of Sleep and Circadian Disorders at the Brigham, in a statement. "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."

With more evidence surrounding the effects of physical activity on cardiovascular health in various patient groups, Qian and a team of colleagues from Brigham and Women’s Hospital sought to evaluate associations of moderate-to-vigorous physical activity with cardiorespiratory fitness and cardiovascular disease risk among patients with type 2 diabetes. To do so, investigators designed their study as an observational analysis of data from the Look Action for Health in Diabetes (AHEAD) study—a major trial that began in 2001 and monitored the health of more than 5,000 patients with type 2 diabetes considered overweight or obese. Of the more than 5000 included in the original study, 2153 provided data related to physical activity from 7-day hip-worn accelerometer.

For the purpose of analysis, patients were categorized into 6 groups based on the time of day with the majority of bout-related moderate-to-vigorous physical activity. These groups were defined as 50% or more of bout-related activity occurring during the same time window, less than 50% of bout-related activity in any single time category, and 1 or more days without bout-related activity per week. Of note, those with 50% or more of their bout-related activity were grouped according to when that activity occurred: morning, midday, afternoon, or evening.

In their analyses, cardiorespiratory fitness was highly associated with timing of bout-related moderate-to-vigorous physical activity (P=.0005), regardless of weekly volume and intensity, but this effect was only present among men (P=.02). When assessing the effect of timing choice, men in the midday group appeared have the lowest level of fitness while the mixed time group was the least fit among women.

Further analysis indicated Framingham risk score was associated with timing of bout-related moderate-to-vigorous physical activity, but this also differed by sex (P=.0007). When assessing for 4-year Framingham risk score, men in the morning group appeared to have the highest score (2.18% [0.70, 3.65]) and investigators noted this association was not seen in women within the study.

"Interest in the interaction between physical activity and the circadian system is still just emerging," Qian said. "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."

This study, “Association of Objectively Measured Timing of Physical Activity Bouts With Cardiovascular Health in Type 2 Diabetes,” was published in Diabetes Care.