Jason T. Brantley, Louisa Tichy, George B. Blackburn, Traci L. Parry. University of North Carolina Greensboro, Greensboro, NC.

BACKGROUND: Cancer cachexia is a complex metabolic and wasting disease that affects up to 80% of cancer patients and results in death in up to one-third of patients. Research has shown that leisure based physical activity can have a positive impact on chronic diseases such as diabetes, heart disease, etc. That being said, little research has been done examining different modalities of exercise and its effects on preserving muscle function and reducing tumor growth in cancer cachectic patients. Therefore, the purpose of this study is to examine the differences between exercise modalities on tumor growth and skeletal muscle function in tumor bearing mice. METHODS: To examine the effect of exercise modalities on skeletal muscle function and tumor growth, male LC3 Tg+ mice underwent a 4-week period of tumor bearing (5x105 LLC cells in flank). Following inoculation, mice were placed into four different training groups (Low Intensity Treadmill Running (LITR), High Intensity Treadmill Running (HITR), Leisure Based Wheel Running (LBWR), and Sedentary). Distance ran during the four weeks was used to compare the three modalities of exercise. Grip strength and tumor growth characteristics were measured to examine the effects of exercise in cancer cachexia skeletal muscle wasting. RESULTS: When comparing distance ran across the three modalities of exercise, the LBWR group ran significantly more than the LITR and HITR groups. Interestingly, the LITR and HITR saw a better response in both tumor growth inhibition and skeletal muscle function. The LITR and HITR groups both had significantly higher grip strength measures compared to the sedentary and LBWR groups. While not significant, the LITR and HITR groups also saw better preservation of grip strength compared to the sedentary and LBWR groups. The same trend is seen for reduced tumor growth. While not significant, estimated tumor volume and estimated tumor mass were considerably smaller for the LITR and HITR groups compared to the sedentary and LBWR groups. CONCLUSION: These data indicate that while the LBWR group was significantly more active, that intensity and structure of exercise may play an important factor in preserving muscle function and reducing tumor growth. Therefore, while leisure-based activity still exerts a modest protective effect, structured exercise appears to provide a greater protective effect for muscle preservation and tumor growth inhibition.

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