No limit to heart health benefits of exercise

There appears to be no limit on the benefits of exercise on cardiovascular health, such that the risk for cardiovascular diseases (CVD) is suppressed even at the highest levels of physical activity (PA), according to a recent study.

“In this study, we found no evidence of a threshold for the inverse association between objectively measured moderate, vigorous, and total PA with CVD,” the researchers said. “Our findings suggest that PA is not only associated with lower risk for of CVD, but the greatest benefit is seen for those who are active at the highest level.”

Information from 90,211 participants in the UK Biobank cohort study were included in the present analysis. Only those with enough and good-quality wrist-worn accelerometer data were eligible. Over 440,004 person-years of follow-up, 3,617 were ultimately diagnosed with CVD, of which 312 were fatal. [PLoS Med 2021;18:e1003487]

PA shared a linear, dose-response interaction with the risk of incident CVD. Compared with the lowest quartile of moderate PA, each increasing category saw a significant drop in CVD risk (Q2: hazard ratio [HR], 0.71, 95 percent confidence interval [CI], 0.65–0.77; Q3: HR, 0.59, 95 percent CI, 0.54–0.65; Q4: HR, 0.46, 95 percent CI, 0.41–0.51).

A similar trend was reported for vigorous PA (Q2: HR, 0.70, 95 percent CI, 0.64–0.77; Q3: HR, 0.54, 95 percent CI, 0.49–0.59; Q4: HR, 0.41, 95 percent CI, 0.37–0.46) and total PA (Q2: HR, 0.73, 95 percent CI, 0.67–0.79; Q3: HR, 0.63, 95 percent CI, 0.57–0.69; Q4: HR, 0.47, 95 percent CI, 0.43–0.52). All estimates were in comparison with the lowest category of exercise.

The principal findings were robust to subgroup and sensitivity analyses. In both men and women, increasing total, moderate-, and vigorous-intensity exercise were linearly associated with decreasing CVD likelihood. There was no threshold beyond which exercise aggravated the risk of developing CVD.

Similarly, differentiating according to the type of CVD yielded the same result. Increasing levels of exercise were significantly protective against both ischaemic heart disease and cerebrovascular disease, with no apparent cap.

“In this large population-based cohort study in adults, we found a linear inverse dose-response association between accelerometer-measured moderate and vigorous PA, as well as total PA and incident CVD, with no threshold of effect at low or high levels,” the researchers said.

The present study employed objectively measured PA data, instead of self-reports, which allowed the accurate capture of leisure and nonleisure PA. Another strength of the present study was its large sample size and prospectively collected data.

An important limitation, the researchers pointed out, is the observational nature of the data, which makes it difficult to eliminate residual confounding and the potential of reverse causality, “where incipient CVD, not yet detected clinically, might lead to reduced PA because it makes it more difficult for an individual to undertake PA.”