Exercise not always beneficial for CV health, study finds

A study published in Hypertension this month has found that exercise—historically one of our best first-line defenses against cardiovascular disease—could also negatively impact heart health in certain situations, including at work.

The idea of physical activity as a modifiable CV risk factor is deep-rooted in the developed world, present in the health guidelines of most countries and taught across elementary, middle and high schools. “Get Active” is number three on the American Heart Association’s list of major CVD risk factors, for example, and last year the AHA updated its guidelines to heavily emphasize the physical, mental and medical benefits of exercise.

But, as Jean-Philippe Empana and his colleagues at Inserm (French National Institute of Health and Medical Research) and the University of Paris know, physical activity can take many forms. Empana and his team paired with researchers led by Rachel Climie at the Baker Heart and Diabetes Institute in Melbourne, Australia, to identify any negative cardiovascular consequences of exercise.

“Our idea was to look at whether all types of physical activity are beneficial, or whether under some circumstances physical activity can be harmful,” Empana said in a release. “We wanted in particular to explore the consequences of physical activity at work, especially strenuous physical activity such as routinely carrying heavy loads, which could have a negative impact.”

The blended team based their research on data from the Paris Prospective Study III, a 10-year-long study that’s been monitoring the health status of more than 10,000 volunteers in the city. Participants filled out a questionnaire about the frequency, duration and intensity of their physical activity, differentiating between exercise through sport, exercise at work and exercise during leisure time.

In addition to the survey, Empana et al. evaluated the CV health of patients through echo tracking—a method for measuring baroreflex sensitivity via ultrasound imaging of the carotid artery. They considered both mechanical baroreflex, a metric assessed through the measurement of arterial stiffness, and neural baroreflex, a metric assessed through the measurement of nerve impulses sent by receptors on the artery’s walls.

Empana and co-authors explained that abnormalities in mechanical baroreflex tend to correlate with aging-related CVDs, while abnormalities in the neural baroreflex are usually a red flag for heart rhythm disorders. In the study, high-intensity exercise from sports activities was linked to a better neural baroreflex, but physical activity at work—like carrying heavy loads on a day-to-day basis—was associated with an abnormal neural baroreflex and greater arterial stiffness.

“Our findings represent a valuable avenue of research for improving our understanding of the associations between physical activity and cardiovascular disease,” Empana said. “They do not suggest that movement at work is harmful for health—instead they suggest that chronic, strenuous activity (such as lifting heavy loads) at work may be.

“This study has major public health implications for physical activity at work. We now want to expand our analysis to further explore the interactions between physical activity and the health status of people in the workplace.”

The researchers are reportedly now working to replicate their results in other populations.