Chemotherapy drugs can damage the heart. Researchers have now, for the first time in humans, demonstrated that physical activity can protect against this damage.
Chemotherapy drugs can damage the heart. Researchers have now, for the first time in humans, demonstrated that physical activity can protect against this damage.
Just a few decades ago, medicine was often powerless against cancer. Any opportunity to fight cancer cells was welcome. At the time, awareness of possible side effects or long-term damage from treatment was just beginning to emerge. "That has changed," says Matthias Wilhelm, medical director of the Center for Rehabilitation and Sports Medicine at Inselspital in Bern. "With the growing number of cancer survivors, it has become increasingly important to understand how harmful side effects can be reduced or even prevented."
As a cardiologist, Wilhelm is primarily interested in anthracyclines. These drugs are a key component of chemotherapy—especially for breast cancer or lymphomas—and are highly effective in fighting cancer cells. Unfortunately, in rare cases, they can also cause permanent damage to the heart muscle. Numerous studies in animal models have shown that damage to the cardiovascular system is reduced when animals engage in sufficient physical activity during chemotherapy.
"But for humans, the data so far has been very limited," says Wilhelm. For this reason, he and his team set up a clinical study to investigate how exercise during or after chemotherapy affects the heart. "We originally planned to enroll 102 patients in our study, but the COVID-19 pandemic threw a wrench in those plans," Wilhelm explains. Between May 2019 and June 2022, he and his colleagues at Inselspital and Lindenhofspital in Bern, Bürgerspital in Solothurn, and Spital Thun were able to recruit 57 patients for the study.
In the study, patients were randomly assigned to either the group with structured exercise during chemotherapy or the control group, which started training only after the treatment. However, all patients in both groups were given a pedometer at the start of the study, with the recommendation to stay active. "We followed the recommendations of the World Health Organization (WHO): It's good to move 150 to 300 minutes a week at moderate intensity," Wilhelm says. This corresponds to the amount of physical activity someone would do if they walked 10,000 steps per day, with at least half of those steps done at a pace that causes faster breathing.
When analyzing the data, it became clear that even those in the control group were very physically active during their chemotherapy. "They moved on average just as much as the patients in the structured exercise group. Therefore, we couldn’t find a difference between the two groups," says Wilhelm. Apparently, the participants were so motivated that just wearing a pedometer and setting the goal of 10,000 steps per day was enough to encourage them to move enough. At the same time, Wilhelm points out that the group training in a cardio-oncology rehabilitation program helped some participants overcome their motivational barriers due to the social interaction and the structured commitment.
When Wilhelm and his team combined the data from both groups and compared individual levels of physical activity with signs of heart muscle damage, they found a linear correlation: "The more steps a person took, the better the heart's pumping function remained," says the sports physician. "We were able to confirm the dose-dependent heart-protective effect of exercise that we had previously observed in animal models, now for the first time in humans."
Wilhelm believes it is time to abandon the idea that cancer patients must spend weeks in bed and rest due to their illness. "From an evolutionary biology perspective, humans are genetically programmed for moderate endurance training as hunters and gatherers," Wilhelm explains. Therefore, it is healthy when behavior aligns with this genetic program. "Cancer doesn’t change that," he adds. Cancer patients should not rest too long but engage in physical activity as much as possible. "This way, they can benefit from the numerous health-promoting substances that are produced in the muscles during physical activity."
HSR-4360-11-2017
