Young Adults Likely Need Five Hours Of Moderate Exercise Weekly To Curb Hypertension Risk In Midlife

Five hours of moderate exercise weekly - double the U.S. minimum physical activity recommendations - are likely needed at age 18 to help reduce the risk of high blood pressure by age 60, especially among Black people, researchers suggest.

"We found that meeting twice the minimum physical activity guideline at age 18 was protective of hypertension regardless of physical activity levels later in adulthood," Dr. Jason Nagata of the University of California, San Francisco told Reuters Health by email. "However, those who are able to mitigate declines in physical activity in middle or older age have additional protection from developing hypertension."

"Healthcare providers should assess for and promote physical activity in the clinical setting," he said. "In addition to getting active, the American Heart Association encourages a healthy diet and stopping smoking as lifestyle changes to improve cardiovascular health."

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"Messaging that promotes optimizing health beyond just needing to avoid risk may be especially salient for young adults," he added.

As reported in the American Journal of Preventive Medicine, Dr. Nagata and colleagues analyzed data from more than 5,000 participants in the the Coronary Artery Risk Development in Young Adults study from four urban U.S. sites.

The cohort was balanced within each center by sex, race (Black and white), age (18−24 years and 25−30 years at baseline), and educational level. About half of participants (51.6%) were Black and 45.5% were men.

Participants self-reported leisure-time physical activity, including frequency and intensity. Moderate-intensity activities included nonstrenuous sports, such as softball; walking; bowling/golf; gardening/ raking; and calisthenics.

From age 18 to 60, physical activity, on average, was lowest among Black women compared with other groups. Black men, on average, reported high levels of physical activity at age 18; however, levels declined considerably from young adulthood to the end of middle age.

Specifically, by the time Black men reached age 60, exercise activity had fallen from a peak of approximately 560 exercise units (EUs) to around 300 EUs - roughly the equivalent of the minimum of two-and-a-half hours a week of moderate-intensity exercise recommended by U.S. guidelines. This was less exercise than white men and slightly more than white women

By age 60, 73.1% of all participants had developed hypertension, including 80%-90% of Black men and women, versus 70% of white men and 50% of white women.

Lower physical activity score (per 100 units) at age 18 years was associated with 4% higher odds of hypertension incidence. Each additional 1-unit reduction per year in physical activity score was associated with 2% higher annual odds of hypertension incidence.

Among participants with high physical activity levels of at age 18 (>600 EUs), dramatic subsequent decreases (loss >2.5 EUs/year) compared with gains were associated with hypertension onset (adjusted odds ratio, 4.11).

As Dr. Nagata noted meeting approximately twice the minimum physical activity guidelines at age 18 (OR, 0.82) and through follow-up (OR, 0.78) was associated with lower odds of hypertension onset; however, meeting the minimum guidelines was not.

Dr. Antoinette Schoenthaler, an associate professor in the Departments of Population Health and Medicine at NYU Grossman School of Medicine in New York City, commented in an email to Reuters Health, "While we know that participation in physical activity declines with age, the rapid decline in Black men and its role in the development of hypertension is a new finding."

"One caveat is that the authors did not look at dietary behavior as a covariate," she noted. "We know that diet also plays an important role in the development and control of hypertension, and that these behaviors differ by race/ethnicity. We don't know if the large percentage of Black men and women with a diagnosis of hypertension by age 60 was due to declines in physical activity, changes in dietary habits, or a combination of both."

"The authors also relied on a self-report measure of physical activity," she said, "which often leads to overestimation."

"Assessing the frequency and duration of physical activity is important, particularly as patients age and become more sedentary due to changing life roles (e.g., retirement, becoming a parent)," she continued. "Understanding the barriers to exercise is equally important."

"Raising the guidelines to recommend more activity may be short-sighted if we don't address the structural and environmental barriers to activity that disproportionality affect Black men and women," she said. "These include safety concerns (see the Running while Black initiative), lack of facilities in their neighborhood, and poor neighborhood conditions (e.g., lack of sidewalks) among others."

—Marilynn Larkin

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