Endurance and resistance exercise training programs elicit specific effects on sciatic nerve regeneration after experimental traumatic lesion in rats.

OBJECTIVE: To evaluate the effects of endurance, resistance, and a combination of both types of exercise training on hindlimb motor function recovery and nerve regeneration after experimental sciatic nerve lesion in rats. METHODS: Sciatic nerve crush was performed on adult male rats, and after 2 weeks of the nerve lesion, the animals were submitted to endurance, resistance, and a combination of endurance-resistance training programs for 5 weeks. Over the training period, functional recovery was monitored weekly using the Sciatic Functional Index (SFI) and histological and morphometric nerve analyses were used to assess the nerve regeneration at the end of the trainings. RESULTS: The SFI values of the endurance-trained group reached the control values from the first posttraining week and were significantly better than both the resistance-trained group at the first, second, and third posttraining weeks and the concurrent training group at the first posttraining week. At the distal portion of the regenerating sciatic nerve, the endurance-trained group showed a greater degree of the myelinated fiber maturation than the sedentary, resistance-trained, and concurrent training groups. Furthermore, the endurance-trained group showed a smaller percentage area of endoneurial connective tissue and a greater percentage area of myelinated fibers than the sedentary group. CONCLUSION: These data provide evidence that endurance training improves sciatic nerve regeneration after an experimental traumatic injury and that resistance training or the combination of 2 strategies may delay functional recovery and do not alter sciatic nerve fiber regeneration.

Treadmill training increases the size of A cells from the L5 dorsal root ganglia in diabetic rats.

The aim of this study was to evaluate the effects of physical training on the L5 dorsal root ganglion (DRG) cells in streptozotocin diabetic rats. Male adult rats were divided into 3 groups: (control, diabetic and trained diabetic). Treadmill training was performed for 10 weeks (5 days/week, twice a day). Blood glucose concentrations and body weight were evaluated 48h after diabetes induction and every 30 days thereafter. Then, animals were killed and the right L5 DRG removed. Histological and morphometric analysis consisted of evaluating nuclear and cellular volumes and areas in A and B cells at light and ultrastructural levels. Blood glucose concentrations were higher in both diabetic groups vs controls at all periods. Body weights were lower in all diabetics vs controls at all periods after diabetes induction, with a significant time vs group interaction. In A cells, the cellular and nuclear volumes were lower than control animals only in the diabetic group; control and trained diabetic animals did not differ; in B cells the cellular and nuclear volumes were lower in diabetic and trained diabetic rats. The cellular areas of A cells were smaller in diabetic rats than in control and trained diabetic rats, while the cellular areas of B cells were smaller in the diabetic and trained groups. In conclusion, treadmill training was able to increase the size of A cells from the DRG in diabetic rats and improved the morphological features of these cells.