(1.Department of Physical Education，Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China；2.College of Sports and Health，Shandong Sport University，Jinan 250102，China；3.Department of Bio-electromagnetic Technology Research, Institute of Electrical Engineering of Chinese Academy of Sciences，Beijing 100190，China)
Abstract: Aerobic exercise was applied to recovery intervention in the rats after blunt contusion of gastrocnemius muscle during the recovery period, so as to explore the effect of the recovery of gastrocnemius muscle with blunt contusion by conducting aerobic exercise via analyses of electromyographic changes. 60 male SD rats were randomly divided into five groups: normal control group (group A), natural recovery group (group B), aerobic exercise group 48h after injury (Group C), constant load aerobic exercise group 7d after injury (Group D), gradually increasing load aerobic exercise group 7d after injury (Group E). The rats were sacrificed at 2d, 5d, 7d, 10d, 14d, 21d, 28d, 30d, 35d and 56d after blunt contusion, and were tested by electromyography. The recovery of gastrocnemius muscle was observed, the resting potential was recorded and the changes of CMAP were inducted during recovery. Results show that: (1) spontaneous potential: the Daube score of spontaneous potential in Group E was significantly lower than that in group C at 21d, 28d and 35d, and that in group D was significantly lower than that in group C on 28d. (2) CMAP latency ratio: the latency of group E was significantly lower than that of group B at 14d, 28d and 35d, significantly lower than that of group C at 14d, 21d, 28d and 35d, and significantly lower than that of group D at 35d. (3) CMAP amplitude ratio: the amplitude of group D was significantly higher than that of group B at 35d and 56d, and that of group E was significantly higher than that of group B at 10d, 14d, 28d, 35d and 56d; the amplitude of group D and E was significantly higher than that of group C at 10 d, 14 d, 21d, 28d, 35d and 56d; the amplitude of group E was significantly higher than that of group D at 10 d and 56d. The study indicates that: during the recovery process of gastrocnemius contusion, aerobic exercise 48 hours after injury can aggravate the abnormal spontaneous potential, prolong the latent period of CMAP, and reduce the recovery speed of amplitude, which is not conducive to the recovery of gastrocnemius contusion and reinnervation of peripheral nerve; after 7 days, incremental aerobic exercise and constant load aerobic exercise can promote the disappearance of abnormal spontaneous potential, shorten the latent period of CMAP, improve the recovery speed of amplitude, which is conducive to the repair and reinnervation of damaged skeletal muscle.
Keywords: sports medicine；gastrocnemius；blunt contusion；aerobic exercise；electromyograph