The impact of caloric restriction versus exercise on tumor and muscle tissue protein synthesis rates in breast cancer patients

Subjects will be randomly assigned to undergo 7 days of either caloric restriction, an exercise program, or standard treatment. The caloric restriction group will undergo a 30% reduction in daily energy intake (~500-600 kcal). The exercise group will increase daily energy expenditure by 30% (~500-600 kcal) by performing 1 h of combined resistance- and endurance-type exercise and 30 min of walking. Patients following standard treatment will act as the control group. All subjects will ingest small amounts of deuterium oxide (2H2O) throughout the 7-day period. The 7-day period will end with the tumor resection surgery, during which a tumor tissue sample, skeletal muscle sample, and plasma sample will be collected. Protein will be isolated from the tissue samples and analyzed for the increase in 2H-alanine enrichment to determine average tumor and muscle tissue protein synthesis rates over the 7-day assessment period (in %/d).

It is hypothesized that both caloric restriction and exercise lower tumor tissue protein synthesis rates but that exercise, as opposed to caloric restriction, will prevent a concomitant decline in muscle tissue protein synthesis rates.

0 days, 7 days

1) dietary energy restriction (-30% from habitual intake), 2) daily exercise (30 min cycling at 70% HRmax, 30 min full body resistance-type exercise, 30 min walking).