EFFECTS OF EXERCISE ON THE IMMUNE-RESPONSE TO CANCER

This study examined the effects of two doses of exercise on tumor inci dence and progression, and the number and activity of intratumoral pha gocytic cells (80% macrophages [M phi's]). Male mice were randomly ass igned to control (CON), moderate (MOD) or exhaustive (EXH) treadmill r unning. Mice were inoculated subcutaneously with 2.5 X 10(5) mammary a denocarcinoma cells after 3 d of running (3 h after the last run at a point when enhancement in M phi cytotoxicity is observed). This tumor was chosen due to its susceptibility to M phi inhibition in vitro and in vivo. Mice continued daily running for 14 d. Food intakes were high er during the last 3 d in MOD and EXH, but body weights were no differ ent. Flow cytometer analysis of tumor masses revealed that MOD had gre ater numbers of phagocytic cells (vs EXH) with slightly higher phagocy tic activities (vs CON and EMI) (P < 0.05). However, no group differen ces in tumor appearance were seen except on day 7 when CON had less ob servable tumors than MOD and EM (P < 0.05). Tumor size was also not di fferent between groups at any point. These results indicate that moder ate exercise can increase the phagocytic capacity of intratumoral phag ocytic cells, but these changes had no apparent effect on tumor incide nce or progression in this study.