The neurophysiological mechanism for increasing strength by resistance training has not been understood precisely. The purpose of this study was to examine the effect of 8 weeks resistance training (RT) on A 12 acetylcholinesterase (AChE) activity in rat muscle. Materials and Methods: In this experimental study, 16 male rats were randomly assigned into two groups: resistance training and control. The 8 weeks (5 sessions/week) resistance training consisted of climbing (3 sets of 4 repeats with a

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... 3 min rest between the sets) a ladder (1 meter height consisted of 26 stairs) carrying a weight 30% of their body weight (suspended from the tail) in the first week and increased to 200% of body weight in the last week. Forty-eight hours after the last training session, the flexor hallucis longus (FHL) muscles of animals were isolated from the posterior lateral side of hindlimb under sterile conditions. Finally, AChE activity was measured for both groups. Results: No significant difference was seen in AChE activity in FHL muscles of the RT group (resistance: 1.31±0.48 vs. control: 1.01±0.29, P=0.226). Conclusion: It seems that resistance training can not significantly increase AChE activity, as an acetylcholine release marker.