45 Minutes of Exercise a Day May Reduce Cancer Risk

More than 46,000 cancer cases could be prevented each year if Americans exercised for 45 minutes a day. That’s according to a new study published in October 2021 in Medicine & Science in Sports & Exercise. And you don’t have to be an Ironman — stepping away from Netflix and walking the dog can help reduce your risk.

Researchers from the American Cancer Society and Emory University wanted to measure the link between cancer and inactivity. They analyzed data from the U.S. Cancer Statistics database by state for Americans 30 and older between 2013 to 2016. They also reviewed two large federal studies asking people how often and in what ways they exercise. The study included nearly 600,000 American men and women. Responses from adults in each state were grouped based on whether they met American Cancer Society guidelines for physical activity: 300 minutes of moderate exercise every week to reduce cancer risk.

Researchers adjusted these statistics for factors such as body mass index and gathered additional data about cancer risks. Their mathematical analysis resulted in 46,356, or about 3% of all cancers annually (excluding nonmelanoma skin cancers), linked to inactivity.

Across states, the occurrence was higher in women (4.1%) than men (1.8%) mainly because of the risk associated with female breast and corpus uteri cancers. By cancer type, men and women generally had similar rates. For both men and women, states in the South, where residents tend to report little exercise, had the highest proportion (3.7% in Kentucky) while those in the Northern and Mountain regions had the lowest (2.3% in Utah). When they looked at individual types of cancer, stomach cancer (16.9%) had the highest overall occurrence of cases attributable to inactivity.

This study is really important in showing that we can prevent a lot of cancer by increasing how physically active we are as a population.

Dr. Nathan Parker, Health Outcomes and Behavior

“This study is really important in showing that we can prevent a lot of cancer by increasing how physically active we are as a population. As the founding director of the National Institute on Aging, the late Dr. Robert N. Butler wrote, ‘If exercise could be packed into a pill, it would be the single most widely prescribed, and beneficial, medicine in the nation,’” said Dr. Nathan Parker in the Department of Health Outcomes and Behavior at Moffitt Cancer Center.

Parker’s research focuses on designing and evaluating exercise interventions, in particular resistance training, to improve cancer treatment outcomes and survivorship.

So does 300 minutes of moderate physical activity seem overwhelming? This research suggests that incorporating about 45 minutes a day of brisk walking could prevent thousands of cancer cases a year.

Keep in mind that everyone starts somewhere, and if you’re not currently doing much physical activity, it may not be feasible for you to immediately reach this guideline this week or next. To reap the benefits, Parker recommends gradually increasing the frequency, duration and intensity of your physical activity until you’re consistently meeting the guidelines.