Moderate or high levels of leisure activities significantly lower risk
Published literature reports controversial results about the association of physical activity (PA) with risk of hypertension. Regular physical activity has also been shown to be effective in reducing the relative risk of developing hypertension by 19 to 30 percent.
In this new study Dr. Wei Ma, MD, PhD, of Shandong University in Jinan, China and colleagues in a meta-analysis of prospective cohort studies examined the effect of physical activity (PA) on hypertension risk.
PubMed and Embase databases were searched to identify all related prospective cohort studies. Thirteen prospective cohort studies were identified; five in North America, six in Europe, and two in Asia. The study included 136,846 participants who were initially free of hypertension, and 15,607 persons developed hypertension during follow-up.
The definition of hypertension varied between the studies but most defined it as a systolic blood pressure of at least 140 mm Hg, a diastolic pressure of at least 90 mm Hg, or use of antihypertensive. Four of the studies recorded hypertension by self-reporting and by using data from a reimbursement medication registry. Two studies defined hypertension as a systolic pressure of at least 160 mm Hg, a diastolic pressure of at least 95 mm Hg, or use of antihypertensive.
Follow-up duration varied widely, ranging from 2 to 45 years (median 9.8 years). During that time, 15,607 of the participants developed hypertension.
The pooled relative risk (RR) of main results from these studies suggests that both high and moderate levels of recreational PA were associated with decreased risk of hypertension (high versus low: RR, 0.81; 95% confidence interval, 0.76–0.85 and moderate versus low: RR, 0.89; 95% confidence interval, 0.85–0.94).
The association of high or moderate occupational PA with decreased hypertension risk was not significant (high versus low: RR, 0.93; 95% confidence interval, 0.81–1.08 and moderate versus low: RR, 0.96; 95% confidence interval, 0.87–1.06).
The researchers write “The results of this meta-analysis suggested that there was an inverse dose–response association between levels of recreational PA and risk of hypertension, whereas there was no significant association between occupational PA and hypertension.”
The researchers explained the difference between occupational physical activity and recreational physical activity “"Generally, high occupational physical activity consists of heavy lifting, prolonged standing, and highly repetitive work, while recreational physical activity is often characterized by dynamic contractions of large muscle groups increasing whole-body metabolism and cardiac output with ability to rest when fatigued.”
The team adds "the international recommendations for health-promoting physical activity should distinguish between occupational physical activity and recreational physical activity."
According to Dr. Ma and colleagues, even though it is not known how exercise reduces hypertension, some likely reasons include exercise has beneficial effects on body weight, total peripheral resistance, and insulin sensitivity. Another possibility is that people who exercise have a healthier lifestyle in general, which might be protective against high blood pressure.
The study did have limitation such as variation in the measurement of physical activity between the studies, and the lack of information about the type of exercise (aerobic versus resistance).
This study appears in the journal Hypertension: Journal of the American Heart Association.
More information on physical activity and blood pressure can be found online at the American Heart Association website.