The intensity of leisure-time physical activity has an effect on the incidence of CVD, irrespective of energy expenditure, according to an analysis of middle-aged adults in the SUN cohort.
After controlling for energy expenditure, risk for CVD was lowest among participants who reported high-intensity leisure-time physical activity (HR = 0.31; 95% CI, 0.12-0.79) and lower among those who reported lower-intensity leisure-time physical activity (HR = 0.76; 95% CI, 0.48-1.21) compared with participants who were inactive. Moreover, researchers observed an inverse association between high-intensity leisure-time physical activity and nonfatal MI (HR = 0.18; 95% CI, 0.05-0.62), but not with stroke.
“The incidence of CVD in our cohort was very low, probably because it is a young, highly educated, healthy, less susceptible cohort,” Maria Hidalgo-Santamaria, MD, from the department of internal medicine at the University of Navarra, Spain, and colleagues wrote in The American Journal of Cardiology. “Despite this suboptimal setting (low absolute risk), the higher intensity group showed 69% less risk of CVD than the inactive group independently of [energy expenditure]. Our findings are consistent with the previous evidence. However, current physical activity guidelines worldwide omit recommending vigorous over moderate physical activity.”
To assess the relationship between the intensity of physical activity and incidence of CVD, researchers examined data from the prospective, cohort SUN project. Participants included Spanish university graduates with no history of CVD recruited from March 1999 to October 2015 (n = 18,737; mean age, 38 years; 61% women).
Using a validated 17-item questionnaire, researchers estimated the average intensity of leisure-time physical activity, including such activities as walking, jogging, athletics, swimming and stair climbing. Weekly hours spent in each activity were multiplied by its typical intensity to calculate baseline metabolic equivalent of task (MET) hours per week. The total MET hours per week were divided by the weekly hours of leisure-time physical activity yielding average METs. Researchers then classified participants into the inactive group (defined by answering “I don’t exercise” in the survey), the lower-intensity group (< 6 average METs) or the higher-intensity group ( 6 average METs). The total MET hours per week served as a weekly estimate of energy expenditure in leisure-time physical activity.
Then, using the inactive group as the reference category and after adjusting for multiple confounding factors, researchers used Cox proportional hazard models to estimate the relationship between the average intensity of leisure-time physical activity and the risk for CVD within 12 years of follow-up. Cox proportional hazard models were also used to estimate the relationship between the average intensity of leisure-time physical activity and the risk for acute MI, stroke and death related to CV causes.
Participants were followed up for a median of 10.3 years.
In this time, there were 127 incident cases of CVD, including 62 nonfatal MIs, 33 nonfatal strokes and 32 CV deaths.
“High-intensity physical activity increases the short-term risk of CVD and sudden cardiac death in some subjects, especially in those with weak physical fitness,” the researchers wrote. “However, in the general population, this is outweighed by the health benefits of regular vigorous physical activity. Although the risk of CVD could rise during exercise, the average lifetime risk is lower in people who exercise harder.” – by Melissa J. Webb
Disclosures: The authors report no relevant financial disclosures.