Good physical shape when younger can reduce cancer risk: study

Being in good physical shape when you’re younger can reduce the risk of cancer — at least for men, new research suggests.

The study, published Tuesday in the British Journal of Sports Medicine, found that men with high levels of cardiorespiratory fitness at a young age were less likely to develop nine types of cancers later on in life, including cancers of the head and neck, esophagus, stomach, pancreas, liver, bowel, kidney and lung.

Typically, cardiorespiratory fitness is linked to lower risks of certain cancers, but prior to this study, there have been very few large, long-term studies reported.

“This study shows that higher fitness in healthy young men is associated with a lower hazard of developing 9 out of 18 investigated site-specific cancers, with the most clinically relevant hazard rates in the gastrointestinal tract,” the authors said in a media release.

“These results could be used in public health policymaking, further strengthening the incentive for promoting interventions aimed at increasing [cardiorespiratory fitness] in youth.”

Researchers from the University of Gothenburg in Sweden looked at over 1 million men who underwent a military fitness test at around 18 years old — a test that was legally required until 2010 — and compared those fitness levels to their rates of cancer diagnoses over the next 33 years.

Researchers analyzed data from the Swedish registry up until the end of 2019, covering background information and medical diagnoses, as well as deaths for those who started military service between 1968 and 2005.

The military test consisted of riding a stationary bike, starting at a low resistance for five minutes and then increasing resistance by 25 watts per minute until the men were too tired to keep going.

Based on the test results, the researchers divided the participants into three categories: low, moderate and high levels of cardiorespiratory fitness.

Cardiorespiratory fitness refers to a measure of the capacity of one’s circulatory and respiratory systems to supply oxygen to the muscles for energy production during physical activity, according to the American Heart Association. It includes one’s ability to do aerobic exercises, such as running, cycling, swimming for sustained periods and climbing stairs.

Dr. Aron Onerup, lead author of the study and postdoctoral researcher in the pediatrics department at the University of Gothenburg, said that as people’s fitness levels increase, the risk of cancer continues to decrease.

The findings showed that, compared to the low-fitness group, those with high levels of cardiorespiratory fitness had a 19% lower risk of head and neck cancer, as well as a 20% lower risk of kidney cancer.

The group with the highest fitness levels also showed a 42% lower risk for lung cancer, although the authors determined that this was due to people’s smoking habits.

As for gastrointestinal cancers, findings showed that those with higher levels of fitness had a nearly 40% lower risk for cancers in the esophagus, the liver, the bile ducts and the gallbladder, and about 20% lower risk for the stomach and colon — a finding that Onerup said he was surprised about.

However, higher levels were also associated with a 7% higher risk of prostate cancer and a 31% higher risk of skin cancer — potentially due to prostate cancer screenings and exposure to sunlight.

With this study being observational, it cannot confirm direct conclusions about cause and effect. Lifestyle information such as diet, alcohol intake, smoking and any changes in cardiorespiratory fitness would need to be taken into account.

A recent study published in the journal JAMA Oncology showed that just four to five minutes of “vigorous physical activity” could reduce the risk of cancer among generally inactive people.

Another study found that just 11 minutes of moderate to vigorous aerobic activity every day can lower the risk of cancer, cardiovascular disease and premature death.