Adolescents with high BMI and low aerobic capacity may be at higher risk of hypertension in adulthood

After adjusting for family history and socioeconomic factors, researchers found that adolescents with a high body mass index (BMI) and low aerobic capacity are at a higher risk of hypertension when they become adults.

Lead researcher Casey Crump, MD, PhD, of Stanford University, and colleagues published their results online in JAMA: Internal Medicine on Jan. 19.

“If confirmed, these findings suggest that interventions to prevent hypertension should begin early in life and include not only weight control but also aerobic fitness, even among those with a normal BMI,” they wrote.

During the past 20 years, the prevalence of hypertension has increased as more people become obese and have a sedentary lifestyle, according to the researchers. In fact, they cited data that showed 1 in 4 adults in the U.S. and the world have hypertension and that the lifetime prevalence of hypertension may exceed 90 percent.

Although hypertension is associated with increased risks of stroke, ischemic heart disease, heart failure, kidney disease and mortality, the researchers mentioned up to two-thirds of adults in the U.S. with hypertension are undertreated or do not receive treatment.

In this cohort study, the researchers evaluated more than 1.5 million men who were at least 18 years old when they underwent a military conscription examination in Sweden from Jan. 1, 1969 through Dec. 31, 1997. Participants with a prior diagnosis of hypertension were excluded.

The researchers obtained aerobic capacity, muscular strength and BMI measurements and followed the men until Dec. 31, 2012.

After a mean follow-up period of 25.7 years, 6.0 percent of the men were diagnosed with hypertension. The median age at the end of the follow-up period was 46 years, while the median age of participants at their hypertension diagnosis was 49.8 years.

The median BMI was 21.4 among men diagnosed with hypertension and 21.1 among men who were not diagnosed with hypertension. Meanwhile the median aerobic capacity was 231.8 watts and 260.4 watts, respectively, while the median muscular strength was 2,000 newtons and 2,020 newtons, respectively.

After adjusting for BMI and other potential confounders, the researchers found that low aerobic capacity was associated with an increased risk of hypertension even among men with normal BMI, while muscular strength was slightly positively associated with a risk for hypertension. Men with low aerobic capacity and high BMI had a 3.5-fold higher relative risk of hypertension compared with me with high aerobic capacity and normal BMI,

In addition, after adjusting for potential confounders, overweight or obese men had a 2.5-fold risk of hypertension compared with those with a normal BMI and a first-degree family history of hypertension was associated with a 1.5-fold risk of hypertension. Further, low height and high weight were independently associated with an increased risk of hypertension.

The researchers mentioned a few limitations of the study, including that they measured physical fitness and BMI only when the men were 18 and didn’t examine changes over time. They also did not have information on measures of adiposity and dietary factors that could have modified the associations between physical fitness or BMI and hypertension. They added that the cohort was young.

“Additional follow-up will be needed to examine these associations at older ages when hypertension is more common,” they wrote.