How much exercise reduces the risk of premature death?

The benefits of regular physical exercise have long been recognized. According to the Centers for Disease Control and Prevention, physical activity can improve your brain health, help manage weight, reduce the risk of disease, strengthen bones and muscles, and improve your ability to do everyday activities. In addition, regular exercise reduces your overall risk of dying prematurely. 

Physical activity is such an important aspect of keeping ourselves healthy that the US Department of Health and Human Services issued Physical Activity Guidelines for Americans in 2018. They recommended that adults engage in at least 150-300 minutes/week of moderate physical activity or 75-150 minutes/week of vigorous physical activity, or an equivalent combination of both intensities. The American Heart Association followed suit, recommending at least 150 minutes per week of moderate-intensity aerobic exercise or at least 75 minutes per week or vigorous aerobic exercise, or a combination of both.

Previous studies have often used a single measurement of a person’s level of physical exercise on which to base statistical analyses and research outcomes. And despite the well-known advantages of regular exercise, it remains unclear whether it is beneficial or harmful to do more long-term moderate or vigorous exercise than is currently recommended. New research, published in the American Heart Association’s flagship, peer-reviewed journal Circulation, has now investigated this question, making use of over 110,000 participants and a study that lasted 30 years. 

Study lead author Dong Hoon Lee is a research associate in the Department of Nutrition at the Harvard T.H. Chan School of Public Health in Boston.  

“The potential impact of physical activity on health is great, yet it remains unclear whether engaging in high levels of prolonged, vigorous or moderate intensity physical activity, above the recommended levels, provides any additional benefits or harmful effects on cardiovascular health,” said Lee. “Our study leveraged repeated measures of self-reported physical activity over decades to examine the association between long-term physical activity during middle and late adulthood, and mortality.”

The researchers analyzed medical data and mortality records from 116,221 people who had participated in two large prospective studies, the Nurses’ Health Study and the Health Professionals Follow-up Study. In the study, 63 percent of participants were female, and more than 96 percent were white adults. The individuals had an average age of 66 years and an average body mass index (BMI) of 26 kg/m² over the 30-year follow-up period. During this time, the researchers documented a total of 47,596 deaths.

Participants were asked to complete questionnaires at enrollment – and then every two years – on demographic, lifestyle, and medical history information. The questionnaires included questions about health, physician-diagnosed illnesses, family medical histories and personal habits such as cigarette and alcohol consumption and frequency of exercise.  Exercise data was reported as the average time spent per week on various physical activities over the past year. 

Moderate exercise included activities carried out at a less energetic level, such as walking, and lower-intensity swimming, weightlifting, calisthenics and working outdoors. Vigorous activities included more energetic aerobic exercises such as jogging, running, swimming, bicycling and even climbing stairs.

The results of the analysis supported the guidelines established by the CDC and followed by the Department of Health and Human Services. Adults who met the guidelines for weekly vigorous physical activity had a 19 percent lower risk of dying overall, and a 31 percent lower risk of dying from cardiovascular disease (CVD) in particular. Adults who met the guidelines for weekly moderate exercise levels had a 20–21 percent lower risk of death overall, and a 22–25 percent lower risk of dying from CVD in particular. 

However, the most striking results pertain to those participants who performed more than double the currently recommended minimum levels of either vigorous or moderate exercise. They had the lowest long-term risk of premature death.  

• Participants who performed two to four times above the recommended amount of long-term vigorous physical activity (150-300 min/week) had an observed 27–33 percent lower risk of CVD mortality and an overall 21–23 percent lower risk of death from all causes.
• Participants who performed two to four times above the recommended amount of moderate physical activity (300-600 min/week) had an observed 28–38 percent lower risk of CVD mortality and an overall 26–31 percent lower risk of mortality from all causes.

In addition, no harmful cardiovascular health effects were found among the adults who reported engaging in more than four times the recommended minimum activity levels.  Previous studies have found evidence that long-term, high-intensity, endurance exercise, such as marathons, triathlons and long-distance bicycle races, may increase the risk of adverse cardiovascular events, including myocardial fibrosis, coronary artery calcification, atrial fibrillation and sudden cardiac death.

“This finding may reduce the concerns around the potential harmful effect of engaging in high levels of physical activity observed in several previous studies,” Lee noted. However, the study also found that engaging in long-term vigorous or moderate physical activity at more than four times the recommended weekly levels did not provide any additional reduction in the risk of death.

“Our study provides evidence to guide individuals to choose the right amount and intensity of physical activity over their lifetime to maintain their overall health,” said Lee. “Our findings support the current national physical activity guidelines and further suggest that the maximum benefits may be achieved by performing medium to high levels of either moderate or vigorous activity or a combination.”

The study highlighted that people who did less than 75 minutes of vigorous activity, or less than 150 minutes of moderate activity, every week over the long term had the greatest risk of premature death. Lee noted that this segment of the current population would benefit most from introducing 75–150 minutes of vigorous physical activity or 150–300 minutes of moderate activity (or an equivalent combination of both) into their weekly routines over the long term.  

Donna K. Arnett is a past president of the American Heart Association (2012-2013) and the dean and a professor in the Department of Epidemiology at the University of Kentucky College of Public Health in Lexington, Kentucky. Arnett served as co-chair of the writing committee for the American Heart Association’s 2019 Guideline on the Primary Prevention of Cardiovascular Disease, but was not involved in the current study. 

“We have known for a long time that moderate and intense levels of physical exercise can reduce a person’s risk of both atherosclerotic cardiovascular disease and mortality,” said Arnett. 

“We have also seen that getting more than 300 minutes of moderate-intensity aerobic physical activity or more than 150 minutes of vigorous-intensity aerobic physical exercise each week may reduce a person’s risk of atherosclerotic cardiovascular disease even further, so it makes sense that getting those extra minutes of exercise may also decrease mortality.”

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By Alison Bosman, Earth.com Staff Writer