We all know exercise is good for us, but moving your body can also help fight some deadly ailments.
Two recent studies show that exercise not only slows solid tumor growth, but it can even speed up recovery in patients with critical illnesses.
The first study, published in the Journal of the National Cancer Institute, compared the growth of breast cancer cells in two groups of mice: a sedentary group and an active “wheel-running” group. After 18 days, the mice who exercised had higher blood vessel density and blood delivery, leading to slower tumor growth, compared to the sedentary mice.
Mark Dewhirst, one of the study authors and the Gustavo S. Montana Professor of Radiation Oncology at Duke University, noted that the results indicate exercise leads to an increase in cell depth within the tumor.
Exercise also increases blood flow to the tumor. This decreases the risk of inadequate blood supply and oxygen, a phenomenon known as hypoxia. Tumors in areas of hypoxia are more aggressive and more resistant to treatment.
“It’s been known in academia logically for a number of years that patients who continue to exercise after a diagnosis of cancer have a better outcome,” said Dewhirst. “I think a lot of people thought that this was due to the fact that they were just fitter, so they could tolerate the treatment better. While [being fit is] certainly part of it, we discovered that ... it’s the act of exercising itself that kills tumor cells.”
The researchers didn’t study the frequency or duration of exercise needed to produce these tumor-shrinking effects. However, Dewhirst explained that exercise in the active mouse group inhibited tumor growth just as well as the chemotherapy drug cyclophosphamide.
A second study, published in Science Translational Medicine, examined the effect of moderate physical activity on mice with a lung injury. Physical activity in the mice led to decreased production of MuRF1, a protein that triggers muscle wasting.
Moreover, the mice who exercised had lower rates of lung inflammation.
The study also examined the levels of G-CSF, a protein known to activate white blood cells, in 93 human patients in critical care. G-CSF has been associated with lower rates of survival in patients with acute respiratory failure.
Before beginning exercise through “early mobility therapy,” the 93 patients had high levels of G-CSF in their bloodstream. The levels of G-CSF dropped significantly in patients who participated in early mobility therapy. Doctors saw no change in patients who didn’t exercise.
For those who are critically ill, Daniel Files, an assistant professor of medicine at the Wake Forest School of Medicine, noted that not much physical movement is actually needed to get the benefit of exercise.
“Most of the movements [the patients] were doing weren’t what an exercise physiologist would call ‘exercise,’” Files said. “Sometimes even sitting up in bed or standing up were all that was needed for a patient to experience more positive results.”