No Limit to Benefits from Physical Activity on Risk of Cardiovascular Disease

An analysis of nearly 100k people from the UK Biobank study suggests there was no upper threshold on the reduction in risk of cardiovascular disease derived from physical activity.

Confirming what many already suspected, a new analysis of data from the UK Biobank cohort study indicates there was no limit to the cardiovascular benefits derived from physical activity.

Results of the analysis, which included data from more than 90,000 patients without cardiovascular disease at baseline, demonstrated the lowest risk of cardiovascular disease was seen among the most active participants—indicating there was no threshold for how much physical activity could lower cardiovascular disease risk.

“This is the largest ever study of exquisite device-measured physical activity and cardiovascular disease. It shows that physical activity is probably even more important for the prevention of cardiovascular disease than we previously thought,” said study investigator Aiden Doherty, PhD, an associate professor at the University of Oxford’s Nuffield Department of Population Health, in a statement. “Our findings lend further weight to the new WHO guidelines on physical activity which recommend at least 150 to 300 minutes of moderate to vigorous aerobic activity per week for all adults.”

In an effort to more clearly define the effects of physical activity on risk cardiovascular disease, Doherty and colleagues from Oxford designed the current analysis as a retrospective cohort study of patients form within the UK Biobank database. While many studies have examined associations between physical activity and risk of cardiovascular disease, investigators noted most of these have relied on self-reported data and few, if any, had examined associations using accelerometer data.

As part of the UK Biobank study, patients were asked to wear an accelerometer over a 7-day period during a time period lasting from 2013-2015. Using this group, investigators identified 90,211 participants without prior or concurrent cardiovascular disease.

From the accelerometer data, investigators extracted total volume of physical activity and this was used to estimate number of minutes spent in moderate and vigorous physical activity per week. Of note, total activity volume and each intensity of physical activity were categorized into equal quarters for the purpose of analysis. The primary outcomes of the study was incident cardiovascular disease, which was defined as the first hospital admission or death from cardiovascular disease.

In their initial assessment, investigators found those in the lowest category of physical activity smoked more, had a higher BMI, had increased levels of C-reactive protein, and were more likely to have been diagnosed with hypertension than those in categories defined by increased physical activity. During 440,004 person-years of follow-up, investigators found there were 3617 incident cases of cardiovascular disease. Analysis revealed a linear dose-response relationship for physical activity, whether measured as moderate-intensity, vigorous-intensity, or as total volume, with risk of incident of cardiovascular disease.

In their analyses, investigators compared risk of incident cardiovascular disease for each category with the lowest category of physical activity. For moderate-intensity physical activity the hazard ratios for each increasing quarter of physical activity relative to the lowest were: 0.71 (0.65-0.77), 0.59 (0.54-0.65), and 0.46 (0.41-0.51). For vigorous-intensity physical activity, the hazard ratios for increasing quarters compared to the lowest quarter were: 0.70 (0.64-0.77), 0.54 (0.49-0.59), and 0.41 (0.37-0.46). For total volume of physical activity, the hazard ratios for increasing quarters compared to the lowest quarter were: 0.73 (0.67-0.79), 0.63 (0.57-0.69), and 0.47 (0.43-0.52).

Investigators cautioned clinicians to consider the limitations of their study and the potential for confounding and reverse causality when interpreting the results of their study.

“The results of this study enhance confidence that physical activity is likely to be an important way of preventing cardiovascular disease. The potential risk reduction estimated in those engaging in relatively high levels of activity is substantial and justifies a greater emphasis on measures to increase levels of physical activity in the community,” said lead investigator Terry Dwyer, MD, a professor in the University of Oxford’s Nuffield Department of Women’s and Reproductive Health, in the aforementioned statement.

This study, “Accelerometer measured physical activity and the incidence of cardiovascular disease: Evidence from the UK Biobank cohort study,” was published in PLOS Medicine.