This article is more than 5 years old. Information may no longer be current.
Moderate physical activity most effective for reducing vascular risk in middle-aged women
Middle-aged women who reported moderate physical activity two to three times per week had lower risks for CHD, stroke and venous thromboembolism compared with women who were inactive.
However, the new data did not reveal progressive reductions in risk for vascular diseases among women who reported increasing the frequency of physical activity.
Researchers assessed the relationship between amount of physical activity and the incidence of vascular diseases in 1.1 million women in the United Kingdom who participated in the Million Women Study. Participants were enrolled from 1996 to 2001 and follow-up concluded in 2012. At baseline, the mean age was 56 years and mean BMI was 26 kg/m2. The women had no history of cancer, CHD, stroke, VTE or diabetes.
Women self-reported their levels of physical activity at the beginning of the study and at 3-year follow-up. After 9% of the participants were enrolled, researchers also asked the women about how often they participated in any exercise. At the 3-year follow-up, women also provided self-reports of hours spent walking, cycling, gardening, doing housework and any activities that caused sweating or increased heart rate.
Mean follow-up was 9 years. During that time, 49,113 women developed incident CHD; 17,822 developed incident cerebrovascular disease including subarachnoid hemorrhage, intracerebral hemorrhage and cerebral infarction; and 14,550 developed incident VTE, including venous thrombosis without pulmonary embolus and pulmonary embolism. Among women aged 55 to 80 years, the absolute risk for CHD was 610 per 100,000 per year, risk for cerebrovascular disease was 252 per 100,000 per year and risk for VTE was 173 per 100,000 per year.
Women who reported physical activity two to three times per week had significantly lower risk for incident CHD, cerebrovascular disease and VTE (P < .001 for all) compared with women who were inactive.
In contrast, “there was not a progressive decrease in risk with increasing frequency of strenuous or any physical activity,” the researchers wrote.
Women who reported daily physical activity had significantly increased risk for cerebrovascular disease and VTE (P < .001) compared with women who reported physical activity two to three times per week. Women who reported daily strenuous physical activity had significantly increased risk for CHD (P = .002) compared with women who reported strenuous activity two to three times per week, but the same comparison was not significant for any physical activity (P = .08).
“Overall, the main difference in risk was between those doing some activity vs. none, with the lowest risks being observed among women doing moderate amounts of activity. … Among active women, there was little evidence of progressive reductions in risk with more frequent activity, and even an increase in risk for CHD, cerebrovascular disease and VTE in the most active group,” the researchers concluded.
In subgroup analyses, the benefits of physical activity on CHD and cerebrovascular disease were greatest among lean women and associations of physical activity and CHD were greatest in past smokers. Subgroup analyses of VTE showed no evidence of heterogeneity between BMI, smoking and socioeconomics.
The researchers also reported no differences in risk between hemorrhagic and ischemic stroke or between VTE with and without pulmonary embolism.
Women who were more active used less medication, which the researchers said was consistent with lower levels of hypertension and hypercholesterolemia in this group at baseline.
In addition, compared with a reference group that had the lowest duration for each activity, women who reported longer durations of walking, gardening, cycling and housework tended to have lower risk for CHD, cerebrovascular disease and VTE.
Miranda E.G. Armstrong
“This is a very large study of 1.1 million middle-aged women, which confirms the benefits of moderately frequent activity for reducing the risk for CHD and stroke. Further, it shows that benefits may be more wide-ranging than previous thought, as the risk for VTE was also lower in women reporting moderately frequent activity when compared to inactive women. We found little evidence to suggest that activity more frequent than a few times per week provided further benefits in relation to these [vascular] diseases,” Miranda E.G. Armstrong, MPhil, PhD, from the cancer epidemiology unit at the University of Oxford, told Cardiology Today.
The researchers noted that they excluded the first 4 years of follow-up in the main analyses to avoid bias by reverse causation and potentially exaggerate differences in risk between physical activity groups.
In an accompanying editorial, Rachel R. Huxley, MA, DPhil, professor of the School of Public Health at the University of Queensland, Brisbane, Australia, wrote that it is well established that some form of physical activity is beneficial to health.
“In healthy, active, middle-aged women, moderate and frequent physical activity was optimal for vascular risk reduction. These findings may offer some hope — and perhaps even a dash of inspiration — to the estimated 30% of adults worldwide who struggle to achieve the recommended levels of physical activity,” Huxley wrote. – by Stephanie Viguers
For more information:
Miranda E.G. Armstrong, MPhil, PhD, can be reached at miranda.armstrong@ceu.ox.ac.uk.
Disclosure: Armstrong and Huxley report no relevant financial disclosures.