Leisure-time physical activity was associated with a lower risk of incident coronary heart disease (CHD) in young women, according to results from a 20-year prospective analysis.
Andrea K Chomistek, ScD, of the School of Public Health at Indiana University in Bloomington, and colleagues specifically chose to study young women since the inverse association between physical activity and CHD has already been demonstrated in middle-aged and older adults.
They gathered data from 97 230 individuals (mean age: 36.6 years at baseline) from the Nurses’ Health Study II (NHSII). Women completed questionnaires regarding physical activity and food frequency beginning in 1991. A total of 544 cases of incident CHD were documented; 254 of which occurred in women younger than 50 years of age.
Women who reported more physical activity were generally younger, had lower BMIs, were less likely to smoke, watched less television, and had higher Alternative Healthy Eating Index-2010 diet scores.
In multivariable-adjusted models, the hazard ratio (HR) of CHD comparing ≥30 with <1 metabolic equivalent of task (MET) hours per week was 0.75 (95% confidence interval [CI]: 0.57-0.99; P=.01). Moderate- and vigorous-intensity physical activity were both inversely associated with CHD risk when analyzed separately.
Women who reported ≥15 MET-hours/wk of moderate activity had a 33% lower risk of CHD compared with women who reported 0 MET-hours/wk (HR: 0.67; 95% CI: 0.51-0.87; P=.01). Similarly, a 23% lower risk of CHD was seen in women who reported ≥15 MET-hours/wk of vigorous activity (HR: 0.77; 95% CI: 0.57-1.03; P=.04) compared with women who reported no vigorous activity.
When researchers evaluated the relationship between frequency of exercise and CHD risk, they found that the HR for women who reported exercising more than 4 times per week was 0.60 (95% CI: 0.46-0.78; P=.0001) compared with women who reported exercising just once per week.
“However, the correlation between frequency and volume of exercise ranged from 0.41 to 0.44 in the questionnaire cycles where both were asked (1991, 2005, 2009),” they wrote. “In the multivariable model that included volume of physical activity, the association between exercise frequency and CHD risk was attenuated and no longer significant (HR comparing extreme categories: 0.94; 95% CI: 0.70-1.25; P=.84), whereas the association for volume of physical activity was nearly identical to that above (HR: 0.76; 95% CI: 0.56-1.02 comparing ≥30 with <1 MET-hours/wk).”
It is also important to note that the results indicate that leisure-time physical activity is associated with a reduction in CHD risk in younger women who are of normal weight, overweight, or obese. This observation has been made in middle-aged and older patient populations, but as the authors pointed out, it is worth emphasizing given the prevalence of overweight and obesity in young and middle-aged women in the United States.
While an elevated BMI is still considered a significant risk factor for CHD, the increased risk associated with being overweight or obese is slightly attenuated by engaging in physical activity.
“Furthermore, exercise did not have to be strenuous to have such associations; moderate-intensity physical activity, including brisk walking, was associated with lower risk of CHD,” researchers wrote. “There was no association between physical activity earlier in life and CHD risk in adulthood, suggesting that previously inactive women who become physically active can still decrease their risk of CHD.”
Chomistek AK, Henschel B, Eliassen AH, Mukamal KJ, Rimm EB. Frequency, type, and volume of leisure-time physical activity and risk of coronary heart disease in young women. Circulation. 2016;134:290-299. doi: 10.1161/CIRCULATIONAHA.116.021516.