"Breast cancer patients can exercise while they’re receiving chemotherapy and achieve meaningful benefits in terms of physical fitness, body composition and self-esteem," lead author Kerry Courneya, of the University of Alberta, said in a statement.

Courneya divided women into three groups: supervised resistance exercise three times weekly, supervised aerobic exercise three times weekly and no aerobic or resistance exercise, also known as the "usual care" group. The median duration of chemotherapy and exercise was 17 weeks.

The study found that resistance exercise was better than usual care for improving muscle strength, lean body mass and self-esteem, while aerobic exercise was better than usual care for improving aerobic fitness, self-esteem and body fat percentage.

In a second study, lead author Alyson Moadel, of Albert Einstein College of Medicine, in New York, found women being treated for early-stage breast cancer, who did yoga, had better quality-of-life compared to breast cancer patients who did no yoga.

The findings were reported in the Journal of Clinical Oncology.