Moderate Exercise Inhibits Progression And Speeds Regression Of An Allogeneic Tumor In Balb/c Mice

Abstract

Previously, we have shown that exhaustive exercise (20–40 m/min, 3hrs) could delay the growth and speed regression of an allogeniec tumor in Balb/c mice and reduce inflammatory cell infiltration and blood vessel density within the tumors (Zielinski et al, J. Appl. Physiol. 96: 2249, 2004). To better represent a more normal exercise paradigm, we wanted to look at the effects of 30 min of moderate exercise on these same variables. Purpose To determine the effects of moderate exercise on the progression and regression rate of a subcutaneously implanted EL4 allogeneic tumor. Methods: EL4 tumor cells (H-2b) were cultured and injected subcutaneously into fifteen 6–12 wk old female Balb/c mice (H-2d). Seven mice ran on a treadmill for 30 minutes at 19 m/min (Ex) while 8 control mice (Con) were subjected to the noise of the treadmill but did not run. The height, length, and width of the tumor were measured in mm daily using Vernier calipers. Volume was calculated using the following equation: pi/6 × H × L × W. Measurements were conducted until the tumors fully regressed. Results There was a significant (F=6.93, p=0.002) time × group interaction such that tumors from the exercised mice were only 60% as large as the controls at peak volume. Moreover, the time until compete tumor regression was accelerated in the Ex mice (day 15) when compared to the Con mice (day 21). Conclusion Moderate exercise exerted a more powerful influence on the kinetics of allogeneic tumor growth when compared to our previous studies using prolonged exercise. We found that moderate exercise increased the regression rate and resulted in smaller tumors female Balb/c mice. Future studies will examine whether moderate exercise influenced the cellular composition of the tumors.