10108965_sThere is strong scientific evidence detailing the beneficial effects of regular exercise, which are likely to go well beyond reducing cardiovascular disease risk factors. Furthermore, exercise benefits can overcome those of common drugs when one considers that exercise combines preventive, multi-system effects with little adverse consequences and at lower cost.  Exercise, and especially contracting muscle, is certainly a source of numerous drug-like molecules with beneficial effects across all ages.  In addition, regular exercise is probably the lifestyle intervention with the most profound upregulating effect on hundreds of genes involved in tissue health implying a complex interaction between muscles and other tissues.  As opposed to exercise, no drug intervention has proven efficient to maintain muscle fitness, a key factor to ensure independent living throughout all stages of life.

http://www.ncbi.nlm.nih.gov/pubmed/23997192