OBJECTIVE: Considering the controversies regarding the best period to begin physical exercise in relation to peripheral nerve regeneration, along with its influence on regeneration, this study accomplished a histomorphometric and functional analysis to evaluate the influence of physical exercise on a treadmill, applied to the immediate and late stages of sciatic nerve regeneration in rats following crushing injury. METHODS: Twenty male Wistar rats (229.05±18.02g) were divided into the following groups: control (CON); denervated (D); denervated+exercise+cage (DEC) and denervated+cage+exercise (DCE). The DEC group started the exercise 24 hours after the nerve injury, while the DCE group started on the 14th day after the injury, with the following protocol: speed=8m/min, inclination=0%, 30min/day, for 14 days. The distal segment of the sciatic nerve was then removed for histomorphometric analysis. The gait was recorded before the operation and on the 7th, 14th, 21st and 28th days after the operation, using the sciatic functional index (SFI). RESULTS: The number of regenerated axons in the D groups was greater than in the CON group (p<0.05), without differences between the D groups. The axon diameter in the DCE group was greater than the diameter in the D group, whereas the other morphometric parameters only showed significant differences with the CON group. There was no difference in SFI values between the groups, whereas within the groups, the 7th and 14th days differed from the values before the operation and on the 21st and 28th days after the operation. CONCLUSIONS: The treadmill exercise protocol that was applied to the immediate and late stages of nerve regeneration did not influence the axonal budding, the degree of maturation of the regenerated nerve fibers or the functional performance of the reinnervated muscles.
nerve regeneration; physical exercise; histomorphometry; sciatic functional index (SFI); neuromuscular plasticity
