Carol Ewing Garber, Ph.D., FAHA, FACSM is a professor of Movement Sciences and Education at Columbia University, a Registered Clinical Exercise Physiologist, the Immediate Past President of the American College of Sports Medicine (ACSM), and lead author of the ACMS’s position stand on the quantity and quality of exercise needed for developing and maintaining cardio, muscular, and neuromotor fitness.
How much exercise should adults get each week to stay healthy?
Most people will significantly improve their health and fitness by doing 150 minutes, or 2 ½ hours, of moderate exercise every week. If you exercise less, you’ll still get benefits, but not as much as if you reached the target amount.
How do you know 150 minutes/week is the right target for health benefits?
Hundreds of large population studies worldwide have compared people’s self-reported exercise habits and various health outcomes. Consistently, active people throughout the globe who exercise about 150 minutes/week or more have a 25%-50% reduced risk of heart disease, diabetes, and some cancers: breast cancer, colon cancer, and prostate cancer. The data adjusts for other potential factors, such as age, preexisting conditions, smoking habits, gender, and nutrition, so this significant risk reduction is an independent effect of being more active.
In addition, hundreds of clinical trials that have randomized a group of people to different exercise programs find that 150 minutes generally leads to improvements in risk factors or biomarkers— e.g., lowering of high blood lipids/cholesterol, high blood pressure, abdominal body fat, insulin resistance levels, blood glucose levels—associated with cancer, heart disease, and diabetes.
A 25% - 50% reduced risk for these diseases is quite a range.
That’s the range we see in the research. A reduced risk of 30% - 40% is most often found, but sometimes it’s lower and other times higher. In all likelihood this variability largely reflects individual differences in people’s responsiveness to exercise.
It’s interesting that this range is similar for most chronic diseases we’ve studied. An equivalent reduction in risk may hold true for other cancers as well; we just don’t have enough data to say yet. Since many cancers have common risk factors, such as being overweight, I think it’s very likely the 25%−50% lowered risk holds true across the board.
How does exercise effect longevity?
On average, people who exercise 150 minutes per week live about two years longer than those who don’t. In other words, for every minute you spend exercising, you add 7 minutes to your life expectancy—not bad odds!
Cynics who don’t like exercise might say, "I'd rather die two years earlier than spend those years doing something I hate," but the larger reality is, when they get older, people who stay active are less frail, more independent, and better able to do activities of daily living than their sedentary counterparts.
Physical activity enables people to do what they like for much longer in their lives.
Are there other vital health benefits associated with exercise?
Most randomized controlled trials of people who are depressed or anxious show starting an exercise program in the recommended range reduces feelings of depression/anxiety. In a two-year intervention study I oversaw, 904 men and women aged 60+ were randomly assigned to one of four groups—physical activity, diet, physical activity and diet, and a control group—and the older adults who exercised about 150 minutes a week reported being in a better emotional state than the non-exercisers. One very nicely conducted Duke University study of 156 men and women aged 50+ found that exercise could be as effective as medication or other therapies for depression. We’ll need a lot more data, though, before we tell people to throw away their medicines.
Overall, then, making a habit of moderate exercise can reduce your risk of heart disease, diabetes, and some cancers by up to half, alleviate depression and anxiety, increase longevity, and contribute to healthy aging. These are powerful effects. No drug can match these benefits. Exercise is truly the best medicine we have.by