Men who improve their cardiorespiratory fitness levels won’t just have an easier time pushing through hard workouts. A new study suggests that they may also be able to reduce their risk of prostate cancer.
For the study, researchers examined data on more than 57,000 men in Sweden who completed multiple cardio fitness tests several years apart to measure their heart rate and how efficiently their body used oxygen during workouts on a stationary bike. They were 41 years old on average and had no history of prostate cancer when they joined the study. After an average follow-up period of almost seven years, 592 men were diagnosed with prostate cancer.
While their initial cardio fitness levels didn’t appear to influence their risk of prostate cancer, changes in fitness over time did make a difference. Men whose cardiorespiratory fitness levels improved by at least 3 percent annually over five years were 35 percent less likely on average to develop prostate cancer during the study period, according to study results published in the British Journal of Sports Medicine.
“Cardiorespiratory fitness essentially refers to how well our circulatory and respiratory systems are able to supply oxygen to our muscles during physical activity or exercise,” says lead study author Kate Bolam, PhD, of the Swedish School of Sport and Health Sciences in Stockholm.
“We don’t know for sure why fitness might reduce risk of prostate cancer,” Dr. Bolam adds. “But we do know that physical activity and fitness have positive effects on inflammation, our immune system, hormones, and body composition — and all these things have been linked to cancer risk for certain cancers.”
During the study period, 46 men died of prostate cancer. Cardiorespiratory fitness levels didn’t appear to make a meaningful difference on survival odds.
Frequent Exercise, Not Just Fitness Level, Likely Lowers Cancer Risk
Beyond this, the link between fitness improvements and reduced prostate cancer risk was weaker for men who started out at high fitness levels than it was for men who had more room for improvement at the beginning of the study.
There are also some caveats to the findings. All of the men were employed, and it’s possible that outcomes might differ for people without steady jobs. Results from Sweden, where most people are white, also may not reflect outcomes for men from different racial or ethnic backgrounds.
It’s also possible that cardiorespiratory fitness levels don’t directly impact cancer risk, says Kerry Courneya, PhD, a professor and director of the Exercise Oncology Laboratory at the University of Alberta in Canada.
“It is unlikely that improved cardiorespiratory fitness itself is responsible for the lower risk of prostate cancer,” says Dr. Courneya, who wasn’t involved in the new study. “Rather, it is likely that cardiorespiratory fitness is a good marker of high quality exercise — with sufficient frequency, intensity, and duration to improve cardiorespiratory fitness.”
Exercises That Help Cardio Fitness
There are a wide variety of workouts that can make a difference — and even people who are out of shape and start gradually with less intense exercises can see improvements, says June Chan, ScD, a professor of urology, epidemiology, and biostatistics at the University of California in San Francisco, who wasn’t involved in the new study.
“Brisk walking, dancing, swimming, Zumba, jogging, cycling, [and] sports are all activities that can help someone get their heart rate up — and increasing heart rate during physical activity is what improves cardiorespiratory fitness,” Dr. Chan says.
Starting gradually in terms of increasing the duration of exercise and the number of workouts a week is the best way to get results, Chan adds. This can help reduce injury, make it feasible to form a new workout routine, and increase the odds that it becomes sustainable over time.
“While how much one increases heart rate and for how long is directly correlated with improving cardiorespiratory fitness, I think it’s important for people to increase gradually from where they are starting, and that means both in terms of duration of activity and number of sessions per week,” Chan advises.