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8th December 2022
Individuals with higher levels of morning physical activity have the lowest risk of incident cardiovascular disease and stroke compared to those who have a midday peak pattern according to an analysis by Dutch researchers.
Cardiovascular diseases (CVD) are the leading cause of global mortality with an estimated 17.9 million lives lost each year. One modifiable factor linked to CVD is physical activity (PA) and data suggests that PA is not only associated with lower risk for of CVD but that the greatest benefit is seen for those who engage in higher levels of activity. However, emerging evidence suggests that the timing of PA may also be an important and influential factor. For example, in a study of more than 7,000 women, researchers found that women who are less active during morning hours may be at higher risk of obesity. In addition, an exercise-based trial which considered the impact of exercise timing on weight loss, showed that morning physical activity led to a significantly higher weight loss compared to evening activity. But mornings might not always be best as a study in men with type 2 diabetes observed that those who undertook high intensity interval training (HIIT) in an afternoon compared to morning session, had better glucose control.
In trying to better understand the impact of the timing of physical activity on the risk of incident CVD, the Dutch researchers collected physical activity data from participants in the UK-Biobank through triaxial accelerometer over a 7-day period which collected 24-hour mean activity levels. The team then used this data to create four different clusters of physical activity: cluster 1 represented the average pattern among the total biobank population which peaked around midday; cluster 2 were those with an early morning peak; cluster 3 a late morning peak and cluster 4, those with an evening peak. Regression analysis was used based on two models, the first (model 1) was adjusted for age and gender, and the second (model 2) additionally adjusted for body mass index and smoking status.
Morning physical activity and cardiovascular outcomes
A total of 86,657 individuals with a mean age of 61.6 years (58% female) were included and followed for 6 years during which time there were 2,911 cases of incident CVD and 796 strokes.
In an analysis based on model 1, participants who had higher levels of morning or later morning (clusters 2 and 3) physical activity, had a 11% (hazard ratio, HR = 0.89, 95% CI 0.80 – 0.99) and 16% (HR = 0.84, 95% CI 0.77 – 0.92) respectively, lower incidence of incident CVD compared to those in cluster 1. However, only those in cluster 3 (late morning physical activity) had a significantly reduced risk of stroke (HR = 0.83, 95% CI 0.70 – 0.98) and ischaemic stroke (HR = 0.79, 95% CI 0.64 – 0.97). Interestingly, when the researchers used model 2, the benefits were no longer statistically significant apart from a reduced risk of ischaemic stroke for those in cluster 3 (HR = 0.73, 95% CI 0.57 – 0.94).
In subgroup analysis based on gender and using model 2, there were statistically significant reductions in the risk of incident CVD but only among women who were either early and later morning exercisers. In addition, the risk of ischaemic stroke was only significantly lower among women in cluster 3 (HR = 0.56, 95% CI 0.38 – 0.83). When stratifying by participant levels of activity (i.e., either less or more active) and using model 2, although there were reductions in the risk of both CVD and stroke, among those who were more active, these reductions were non-significant.
The authors concluded that morning physical activity was associated with lower risks of incident cardiovascular diseases and that these findings highlighted the potential importance of chrono-activity in CVD prevention.
Albalak G et al. Setting your clock: associations between timing of objective physical activity and cardiovascular disease risk in the general population. Eur J Prev Cardiol 2022