Study on Weekly Resistance Training Finds Sweet Spot for Heart Protection

Women engaged in regular resistance training had substantially better cardiovascular health in the long run, according to a large cohort study.

Those performing at least 2 hours a week of resistance training had a 20% lower risk of incident major cardiovascular disease (CVD) compared with no resistance training (HR 0.80, 95% CI 0.69-0.92) over an average 14.5 years of follow-up in the Nurses’ Health Study (NHS) and NHS II cohorts.

This association persisted after adjustment for diabetes, hypertension, hypercholesterolemia, and related medications (HR 0.86, 95% CI 0.75-0.98). Additionally, each additional hour of resistance training per week was associated with a 5% lower risk of major CVD (HR 0.95, 95% CI 0.92-0.99), Edward Giovannucci, MD, ScD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues found.

“A key question is how much resistance training adds beyond aerobic activity alone. In our primary analyses, the associations of resistance training with CVD were attenuated but remained inverse even after adjustment for total aerobic activity, indicating that resistance training is associated with lower CVD risk above and beyond overall aerobic activity while still occurring within a broader healthy behavioral phenotype,” Giovannucci’s group reported in the Journal of the American College of Cardiology.

Resistance training generally means using weights, bands, or bodyweight to build muscle; strength training is a type of resistance training that employs heavier weights. Current U.S. physical activity guidelines recommend performing resistance exercise at least 2 days per week, plus 150 minutes of moderate-to-vigorous aerobic activity.

In this study, the lowest risk of major CVD was found in women who met recommendations for aerobic activity (≥15 metabolic equivalent of task hours per week), engaged in regular resistance training (≥1 hour/week), and reported low television viewing (<2 hours/day).

These women had a 40% reduced risk (HR 0.60, 95% CI 0.53-0.69), compared with the 27% reduced risk of peers who met aerobic and low sedentary television viewing recommendations but not resistance training (HR 0.73, 95% CI 0.67-0.80).

“These findings suggest that, within an already active population, RT [resistance training] is associated with additional reductions in CVD risk above and beyond overall aerobic activity,” said Tianyue Zhang, MD, also of the Harvard T.H. Chan School of Public Health, in a press release. “Alongside aerobic activity and reductions in sedentary behavior, RT may be an important component of public health strategies for cardiovascular prevention in women.”

For their analysis, Giovannucci and colleagues included a total of 117,025 women pooled between the NHS (2002-2020) and NHS II (2003-2017), two ongoing cohorts of registered nurses in the U.S.

Baseline age was on average 66.8 years in NHS and 48.1 years in NHS II.

Investigators sought participants who had up to five repeated assessments of physical activity for the study. Resistance training was reported every 4 years, and time-varying cumulative averages were calculated to estimate long-term exposure.

Women with greater levels of baseline resistance training were more likely to have lower body mass index, higher levels of aerobic physical activity, higher dietary quality, and lower prevalence of diabetes, hypertension, and high cholesterol. They also reported less sedentary time for television viewing and were more likely to use multivitamins.

Major CVD was defined as the composite of myocardial infarction (MI), stroke, coronary artery bypass grafting, or percutaneous coronary intervention.

Of note, study authors reported that resistance training at least 2 hours weekly was tied to fewer MIs in particular (HR 0.56, 95% CI 0.41-0.76) but made no difference in stroke (HR 0.99, 95% CI 0.80-1.23).

Additionally, a lower risk of major CVD was observed only among women who achieved the recommended level of resistance training (cumulative average ≥1 hour/week) and consistently engaged in resistance training (≥75% of follow-up cycles).

“Leveraging repeated measures across two large cohorts of women, our study not only delineates the dose-response association of resistance training with CVD risk, but also clarifies its relationships with MI and stroke and embeds resistance training within an integrated pattern of aerobic activity and sedentary behavior,” wrote Giovannucci’s group.

However, the authors acknowledged, the study had possible measurement errors as resistance training had been self-reported and lacked detailed information on training modality, intensity, and supervision. Moreover, residual confounding cannot be ruled out for such an observational analysis.