New Mouse Research Shows How Physical Activity Starves Cancer Cells
A new study suggests that exercise may slow tumour growth by altering the body’s metabolism so that muscles, rather than cancer cells, absorb the glucose required for growth. The findings, observed in mice, offer fresh insight into why active individuals tend to have lower cancer risk and better survival rates.
Researchers already know that exercise supports gut health and strengthens the immune system. Now, evidence points to a third pathway: metabolic competition between healthy tissue and tumours.
Tumours Shrink When Muscles Take the Fuel
The research, led by Rachel Perry at Yale School of Medicine, involved 18 mice injected with breast cancer cells. Twelve were fed an obesity-inducing diet, since obesity is known to worsen several cancers. Half the mice had access to a running wheel and exercised voluntarily.
After four weeks, obese mice that exercised developed tumours that were 60% smaller than those in obese sedentary mice. Their tumours were also slightly smaller than those in non-obese sedentary animals. A single 30-minute exercise session increased glucose and oxygen uptake in muscle and heart tissue while lowering glucose uptake inside tumours.
“This work reveals that aerobic fitness fundamentally reshapes metabolic competition between muscle and tumours,” Perry said. “We’re not talking about marathon training — just voluntary movement.”
Genes Shift Toward Muscle Growth, Away From Cancer Growth
Gene-activity analysis identified 417 genes involved in key metabolic pathways that changed in response to exercise. The shift meant muscle cells burned glucose more efficiently, while tumour cells took in less. A reduction in activity of mTOR — a protein central to cell growth — was also linked to slowed tumour expansion.
Because metabolic pathways are highly conserved across mammals, Perry expects similar effects in humans, regardless of body weight. Comparable gene-activity changes have already been observed in exercising cancer patients.
“It is another mechanism demonstrating how exercise creates a more cancer-suppressive environment,” said Rob Newton of Edith Cowan University. He emphasised the need for clinical trials but said the effect is likely to translate to humans.
Exercise as a True Cancer Intervention
The findings may clarify why low muscle mass is linked to higher cancer mortality. If muscle tissue competes more effectively for glucose, people with more muscle — and who activate it regularly — may create an internal environment that limits tumour growth.
Newton argues that exercise should be viewed not as an optional lifestyle choice but as a therapeutic tool. “It could be increasing cardiorespiratory fitness, but if a patient has exceptionally low muscle mass, then that probably needs to be targeted first with resistance training.”
Perry adds that metabolism links multiple systems, including the microbiome and immune response. “I would be shocked if the beneficial effects weren’t due to multiple mechanisms,” she said.
