Exercise, the Immune System and Cancer-Suppressive Myokines

A single bout of exercise mobilizes natural killer cells, T cells and macrophages, but levels return to baseline within hours, so benefits likely build from repeated bouts. Regular training may increase immune cell infiltration of tumors, reshape the T cell repertoire, reduce inflammation and improve gut health. Francesco defines myokines as molecules released by contracting muscle, with more than 600 identified. IL-6, decorin, irisin, SPARC and oncostatin act on muscle, fat and other organs. In his group's study of men with advanced prostate cancer, serum taken right after interval training inhibited cancer cell growth more than serum from baseline or 30 minutes later. After 12 weeks to six months of training, cancer cell growth fell by about 20% versus controls. Across studies, acute bouts consistently suppress cancer cell growth, while results from chronic training at rest are mixed, likely because myokines clear quickly. He concludes that moderate to high intensity sessions, high weekly volume and changes in body composition matter, though precise dosing still needs research.