Impact of Resistance Training-Protein Supplementation on Lean Muscle Mass in Childhood Cancer Survivors

This double-blind placebo controlled study will randomize adult survivors of childhood cancer who are 18 to 44 years of age, greater than ten years post first cancer diagnosis, and with low lean muscle mass to two groups: Resistance Training + Supplement (RT+S) or Resistance Training + Placebo (RT+P). Randomization will be stratified by sex and age (18-29 and 30-44 years) in a block size of 4. Three weekly resistance training sessions will occur over a 24 week period. The participants, investigator, trainer and individuals involved in testing will be blind to group assignment. Participants will receive information about physical activity and its health benefits. They will be randomly assigned to one of two groups to receive individually tailored resistance training three times per week for 24 weeks. One group will receive a protein supplement, while the other group will receive a sports drink (placebo). To assess outcomes, participants will have the following research tests: * Blood will be drawn to assess heart health. * Questionnaires will be completed to assess physical activity and health as well as food intake. * Blood pressure measurement. * Electrocardiogram to assess heart health. * Height, weight, waist and hip measurements. * Lean muscle mass will be measured by dual x-ray absorptiometry (DEXA scan). * Muscle strength will be measured by handgrip, knee extension, and ankle dorsiflexion. * Walking speed to determine usual walking speed. * Six-minute walk test to determine endurance. * Physical activity will be monitored by having the participant complete a survey and wear a small recording device (accelerometer) for seven days. Study Objectives: * To evaluate the effects of 24-week supervised RT+S compared to RT+P on changes in lean muscle mass, muscle strength, walking speed, self-reported exhaustion and physical activity levels among childhood cancer survivors. * To evaluate the effects of 24-week supervised RT+S compared to RT+P on changes in blood pressure, high density lipoprotein, triglycerides, abdominal obesity, fasting glucose, fasting insulin, and C-reactive protein among childhood cancer survivors.