Effects of treadmill training on hindlimb muscles of spinal cord injured mice

Treadmill training is known to prevent muscle atrophy after spinal cord injury (SCI), however, the training duration required to optimize recovery has not been investigated. Methods: Hemisected mice were randomized to 3, 6, or 9 weeks of training or no training. Muscle fiber type composition and fiber cross-sectional area (CSA) of medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) were assessed using ATPase histochemistry. Results: Muscle fiber type composition of SCI animals did not change with training. However, 9 weeks of training increased the CSA of IIB and IIX fibers in TA and MG muscles. Conclusions: Nine weeks of training after incomplete SCI was effective in preventing atrophy of fast-twitch muscles but there were limited effects on slow-twitch muscles and muscle fiber type composition. These data provide important evidence of the benefits of exercising paralyzed limbs after SCI.