The neuromuscular electric stimulation (NMES) is an important tool used in sports medicine to accelerate the recovery process. The objective of this study was to analyze the effects of NMES during immobilization of the gastrocnemius muscle, in lengthened (LP) and shortened positions (SP). Sixty young female Wistar rats were distributed into six groups and followed for 7 days: control (C); electric stimulation (ES); immobilized in shortening (ISP); immobilized in lengthening (ILP); immobilized in shortening and electric stimulation (ISP + ES) and immobilized in lengthening and electric stimulation (ILP + ES). For the immobilization, a tubular mesh and cotton rolls together with the plaster were wrapped around the rat's right posterior paw. NMES in a frequency of 50 Hz was used 10 minutes a day, totaling 20 contractions in each session. After 7 days the animals were sacrificed and their gastrocnemius muscles of the right paw were submitted to a mechanical test of traction in a universal test machine (EMIC?). From the load versus elongation curves the following mechanical properties were obtained: elongation in the yield limit (EPL), load in the yield limit (LPL) and stiffness. The SP and LP immobilizations promoted significant reductions (p < 0.05) in the EPL and LPL properties, being more remarkable in the ISP group. When the NMES was used, there was significant increase (p < 0.05) of these properties only in the ISP group. As for stiffness, significant reduction was observed (p < 0.05) only of the C group for the ISP group. When the NMES was used, the stiffness of the ILP + EE group was significantly (p < 0.05) higher and closer to the C group than of the ISP + EE group. We conclude that in this experimental model the immobilization of the muscles in the lengthened position delayed the atrophy process and the electric stimulation during the immobilization contributed to the maintenance of the mechanical properties during the immobilization period, mainly for the ILP + ES group.
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