Cancer-related fatigue and muscle wasting have received significant attention over the last few decades with the goal of establishing interventions that can improve cancer patient life quality and survival. Increased physical activity (PA) has shown to reduce cancer associated fatigue and has been proposed as a promising therapeutic to attenuate cancer induced wasting. However, significant gaps remain in our understanding of how PA impacts the compositional and functional changes that initiate muscle wasting. The purpose of the current study was to determine the effect of wheel exercise on body composition and functional indices of cancer cachexia prior to the development of significant wasting.
Thirteen-week old male ApcMin/+ (MIN) and C57BL/6 (B6) mice were given free wheel access (W) or a locked wheel (Sed) for 5 weeks.
Wheel activity was reduced in the MIN compared to B6; however, wheel access increased Complex II expression in isolated skeletal muscle mitochondria regardless of genotype. Wheel access had no effect on tumor burden or plasma IL-6 in the MIN. MIN-W increased body weight and lean mass compared to MIN-Sed, and there was a direct correlation between wheel distance and lean mass change. MIN-W increased grip strength and treadmill time to fatigue compared to MIN-Sed. Within MIN-W mice, skeletal muscle fatigability was only improved in high runners (>60min/day).
Our results suggest there were therapeutic benefits of increased activity related to body composition, behavior, and whole body function that were not dependent on exercise duration; however, there was an exercise threshold needed to improve skeletal muscle fatigability in tumor-bearing mice. Interestingly, wheel access was able to improve compositional and functional outcomes without mitigating tumor number or size.