Detraining after tumor-bearing accelerates tumor growth while continuous training decreases tumor growth in mice

Abstract

Abstract Objective Previous studies have shown that exercise suppresses tumor growth. However, the effects of exercise with different intensities and exercise detraining after tumor-bearing on tumor progression remain unclear. The purpose of this study was to investigate the effects of continuous and disrupted free and exhausted swimming training after tumor-bearing on tumor progression in melanoma B16-F10-bearing C57BL/6 mice. Methods C57BL/6 mice were subjected to free or exhausted swimming exercise training for 4 weeks prior to the injection of melanoma B16-F10 cells. Subsequently, the B16-F10-bearing mice were maintained with training consisting of free or exhausted swimming or without exercise for 2 weeks during the tumor challenge. Results The tumor weight was increased by 42% and 109% in mice with 4-week exhausted swimming prior to B16-F10 tumor cells inoculation followed by 2-week training cessation compared with the tumor-bearing control (P Conclusions These results suggest that maintaining exercise intensity after tumor-bearing slows tumor growth in mice, possibly because of the enhanced proliferative activity of splenic lymphocytes rather than natural killer cell infiltration. However, detraining after tumor-bearing might accelerate tumor progression because of the reduced proliferation of splenic T lymphocytes.