The purpose of the present research was to study the effects of mental practice on the strength gain and electromyographic changes in elbow flexor muscles. 16 healthy, non-athlete men with 22.5±1.36 years of age, 175.18±6.62 cm of height, 68.78±7.05 kg of weight, and 20.81±3.71 motor imagery ability without any record of injury in elbow, shoulder, wrist, and elbow tendons and flexor muscles were selected and randomly divided into an experimental group (8 subjects) and a control group (8 subjects). The experimental group imagined maximum voluntary contractions of the elbow flexors for four weeks and five sessions a week. The control group did not participate in any physical or mental practice, but they were included in all the measurements. The exercise program involved the imagery of 50 maximum voluntary contractions in two rounds with 25 repetitions. The maximum voluntary contraction (MVC) and integrated electromyography (IEMG) were measured during maximum voluntary contractions of the elbow flexor muscle group in the pretest and the posttest. Student’s t-test was applied for data analysis at significance level. The results revealed that the strength of elbow flexor muscles increased by 30% in the experimental group and5% in the control group and a significant difference was observed between the experimental group and the control group in the strength gain of elbow flexor muscles. Moreover, integrated electromyography increased significantly in the elbow flexor muscles of the experimental group and decreased significantly in elbow extensor muscles. The overall results of the research suggested that mental practice can increase the strength of elbow flexor muscles and this strength gain is apparently associated with the changes in the programming of the central nervous system which has led to an increase in the level of activation of agonist muscles.
