Aerobic Exercise Reduces Bone Wasting in Patients Receiving Chemotherapy

PORTLAND,Oregon—Aerobic exercise can sharply reduce the bone-wasting effects of chemotherapy, according to Anna L. Schwartz, PhD, associate professor and research scientist at the Oregon Health and Science University School of Nursing in Portland. Osteoporosis is becoming an increasingly common and troublesome side effect of chemotherapy, particularly in breast cancer, she reported. In addition to the treatment regimens, premature menopause and inactivity all contribute to a decline in bone mineral density (BMD). Aerobic exercise can reduce this decline and help prevent treatment-related weight gain while increasing muscle strength.

Exercise can thus play an important role in maintaining quality of life and functional capacity during and after cancer treatment, Dr. Schwartz said. She reported on a study that randomized newly diagnosed cancer patients to three groups: aerobic exercise, resistance exercise, and usual care. All of the patients were women and they were also randomized by menopausal status. Persons with metastases, psychiatric disorders, endometrial disease, and diabetes were excluded.

Similar Demographics

The three groups had substantially similar demographics and range of treatments, Dr. Schwartz said. At the outset, the researchers evaluated each subject’s body composition, the bone mineral density of the lumbar spine, and muscle strength measured by 1-repetition maximum tests, and functional ability measured by a 12-minute walk.

Both exercise groups were asked to engage in vigorous physical activity at home for 15 to 20 minutes at least 4 days each week. Members of the aerobic group could choose an exercise that that they enjoyed, for example, walking, dancing, bicycling, or swimming. Resistance group members did a program of exercises using TheraBands, Dr. Schwartz said.

The usual care group got no special guidance on exercise. Some of its members began exercising on their own, but most stopped within 1 or 2 weeks. All subjects underwent the walk test 3 and 6 months into the study and had body composition and lumbar spine evaluations at 6 months.

Exercisers Got Much Stronger

Both exercise groups got "much stronger," Dr. Schwartz noted, while the usual care group lost strength. Although everyone lost bone density, the aerobic exercisers lost the least, 0.69% at the lumbar spine. The control group, meanwhile, suffered "huge declines in a very short time," Dr. Schwartz said, losing 7% in 6 months. Premenopausal women lost more than postmenopausal women.

Among individuals in the groups, initial leg strength and speed predicted bone loss. Dr. Schwartz speculated that "women who are stronger are able to put more torque on their bones," possibly helping to prevent bone loss. Aerobic exercisers gained the least weight and also gained more muscle than resistance exercisers. The usual care group lost muscle.

Dr. Schwartz acknowledged that this preliminary analysis has a number of limitations. The exercise regimens were not supervised and patients received a variety of treatments. The exercise interventions were not developed with the intention of preserving bone. And the so-called aerobic exercises included both weight-bearing activities such as walking and nonweight-bearing activities such as swimming or bicycling, which might have different effects on bone.

Still, she said, it is clear that regular exercise can make important contributions to the well being of cancer patients.