March 18, 2019 | 3 minute read

There is already strong research showing that regular exercise lowers the risk of developing colon cancer. Evidence also indicates that being active can help colon cancer survivors live longer and stay healthier.

Now a new investigation finds that short, intense bouts of exercise reduce the growth of colon cancer cells. This was a small pilot study that needs more follow up to show whether these findings translate to people in real life situation. But it does suggest important insights into how exercise overall and the exercise level may contribute to suppressing colon cancer growth.

The study was published in The Journal of Physiology.

The study is important in adding to a growing body of evidence on the potential benefits of high intensity interval training or HIIT. HIIT is a form of aerobic training that pushes your body with repeated, short spurts of cardio, separated by low-intensity exercises. A HIIT session generally takes less time overall than a typical moderate intensity session of exercise.

The vast majority of studies investigating exercise and colon cancer — and all other cancers — focus on what happens following relatively long periods of moderate or vigorous activity. Only recently has HIIT become a popular area of interest, with numerous studies indicating that these relatively short sessions of intense exercise offer distinct health benefits.

In this pilot study, scientists wanted to see if this intense exercise could cause short and long-term changes in the blood that would reduce cancer cell growth.

The study included 20 men who had completed treatment for colorectal cancer. Half the men did a single high-intensity cycling session; the other half did twelve of the same sessions spread over four weeks. The men who completed the single session had blood samples collected immediately and two hours after they exercised. The long-term HIIT group had blood samples taken after their four weeks of training was finished.

Researchers then added the part of the blood called serum into a laboratory dish containing colon cancer cells. Serum has no white or red blood cells, and no clotting compounds.

Three days later, the researchers saw reduced colon cancer cell numbers only in the sample taken immediately following the HIIT, and not in all of the other samples. The first sample also showed increased indicators of inflammation. This was somewhat perplexing, as the study points out, given that chronic inflammation is linked with cancer incidence.

The changes following HIIT suggest that repeating these exercise bouts regularly could lead to systemic changes that would make the body less conducive for colon cancer cell growth, the authors write.

Colon cancer cells in people do not grow the same way as cancer cells grow in a lab dish. More and larger studies are needed to translate how these findings may affect people.

What is clear now is that adults can lower their colon cancer risk from being active in all types of ways. AICR’s Third Expert Report found that everything from walking to work, gardening, or playing sports contributes to lowering colon cancer risk. Maintaining a healthy body weight, limiting red and processed meat, drinking less alcohol and eating more whole grains and fiber also help prevent this cancer.

Want to find out if you are active enough for good health and a lower cancer risk? Take our quiz.

The study was funded by The University of Queensland and Sports Medicine Australia Research Foundation.