 We propose to test an individually tailored physical exercise intervention, including both aerobic and resistance exercise, for reducing CRF in prostate cancer patients receiving radiation therapy. The proposed research will provide detailed information on the efficacy and acceptance of a home-based aerobic and resistance exercise program for CRF among prostate cancer patients receiving radiation. Data regarding the influence of this intervention on potential factors related to CRF, including loss of strength, muscle atrophy and inflammatory biomarkers will be gathered. The purpose of the proposed study is to extend the positive findings from a feasibility study showing that our tailored home-based aerobic walking and progressive resistance exercise program was effective in reducing CRF and improving strength, skeletal muscle mass, aerobic capacity and quality of life in a small sample of prostate and breast cancer patients N38. 