Sep 19, 2014 10:23 AM EDT By Staff Reporter, UniversityHerald Reporter

Exercise along with chemotherapy shrunk tumors more than chemotherapy alone, according to a study by the University of Pennsylvania.

The new study was conducted to determine whether exercise can prevent cardiac-related side effects caused by cancer drug doxorubicin. Although the drug is effective against several types of cancer, it damages heart cells and causes heart failure in the long-term.

"The immediate concern for these patients is, of course, the cancer, and they'll do whatever it takes to get rid of it," Joseph Libonati, an associate professor in the School of Nursing and director of the Laboratory of Innovative and Translational Nursing Research, said in a statement. "But then when you get over that hump you have to deal with the long-term elevated risk of cardiovascular disease."

Previous studies showed that physical and psychological benefits of exercise among cancer patients. Engaging in exercise routine prior to receiving chemotherapy protects heart cells from the toxic effects of doxorubicin.

This is the first study to determine whether exercise during chemotherapy could prove beneficial for cancer patients.

For the study, the researchers injected melanoma cells in the scruffs of mice's neck. Two groups received doxorubicin in two doses, while the other two groups were subjected to placebo injections. Mice in each of the distinct groups participated in an exercise regimen, walking 45 minutes five days a week on treadmills, while the rest of the mice remained inactive.

The researchers measured the animals' hearts using echocardiogram and analysed their tissues after two weeks. They found that doxorubicin disrupted heart's function, reduced its size and triggered increased fibrosis, even in mice that exercised.

"We looked, and the exercise didn't do anything to the heart - it didn't worsen it, it didn't help it," Libonati said. "But the tumor data -- I find them actually amazing."

However, mice that received chemotherapy and exercised had smaller tumors than those that only received doxorubicin. The researchers believe that exercise increases blood flow to the tumor, bringing more drug in the bloodstream.

"If exercise helps in this way, you could potentially use a smaller dose of the drug and get fewer side effects," Libonati said.

The finding could help develop drugs that mimic the effects of exercise.

"People don't take a drug and then sit down all day," Libonati said. "Something as simple as moving affects how drugs are metabolized. We're only just beginning to understand the complexities."

The finding is published in the American Journal of Physiology.   

See Now: Covert Team Inside Newsweek Revealed as Key Players in False Human Trafficking Lawsuit