Much effort and attention has been directed recently toward the problem of breast cancer and it has led to earlier diagnosis of the disease and better survival rates. But even more improvements might now be made through exercise since Texas A&M researchers have found a direct link between muscle contraction and a reduction in breast cancer.

Scientists reported their findings in the journal Frontiers in Physiology and detailed how an unspecified factor is released during exercise that has the ability to suppress signaling within breast cancer cells. That substance inhibits tumor growth and can even kill cancer cells.

"For this study, we took a deeper look into the relationship between people who exercise more and have less of a risk of cancer; previously, it was believed that there wasn't anything mechanistically linked," said Texas A&M professor Amanda Davis. "Rather, it was just the general benefits seen in your body because of a healthy lifestyle. These data are exciting because they show that during muscle contraction, the muscle is actually releasing some factors that kill, or at least decrease the growth of, neoplastic (abnormal, often cancerous) cells."

Working with specifically bred mice, Davis and her team found that factors which inherently reside in muscle get released into the bloodstream during exercise regardless of a person’s activity level or how developed their muscles.

"Our results suggest that whether you consistently exercise or you just get up and walk when you're not used to working out, these factors are still being released from the muscle," Davis said. "Even simple forms of muscle contraction, whether it be going on a walk or getting up to dance to your favorite song, may play a role in fighting breast cancer.

"The big message is to get up and move," she continued. "You don't have to be an Olympic-level athlete for these beneficial effects to occur during muscle contraction; being physically fit doesn't make you more likely to release this substance."

The mice ran on the treadmill to complete a moderately intense activity routine over a five-week period with the incline gradually being raised during that time. Researchers were not able to identify the minimum amount of exercise necessary but did note the longer the sessions, the more cancer fighting factors were released.

Davis recommends an exercise routine consistent with American College of Sports Medicine protocols which call for 30 minutes of moderate intensity exercise five days per week.

"The decreased risk of breast cancer with exercise comes from the idea that if you have pre-neoplastic cells and you're exercising a lot and slowing their growth, maybe those precancerous cells can be destroyed by the body before they start taking over," Davis said.

More work needs to be done to see if resistance training has the same effect as aerobic exercise and whether different types of cancers are likewise affected. The bulk of the work was focused on the luminal A line of breast cancer, which is the most common type and makes up about 60 percent of the cases.

"These are definitely exciting data we have concerning exercise and breast cancer," Davis said. "However, exercise is not a 100% guarantee. Further research in this area will help to identify why some people who work out regularly are still diagnosed with cancer."

Click here to read more in the journal Frontiers in Physiology.