Comparison the effect of two types of isotonic and isometric resistance training on untrained leg strength and EMG changes in untrained male students

The purpose of the present study was to determine the effects of two types of resistance exercise training (isotonic and isometric) on bilateral transfer effect (cross education). Subjects (n=40، untrained for least 6 months) were randomly assigned to a control group or one of the two groups of resistance training that trained their knee extensor muscles unilaterally. Training was 3 times/wk for 6 wk with three sets of 6-8 repetition (2 minutes rest interval) maximum at 80% one repetition maximum (1RM) for isotonic group and for isometric group، resistance training program was 30 isometric extension maximal voluntary contraction (MVC) for 2-4 second with 15 second rest between each contraction. Control subjects attended sessions but did not exercise. Knee extensor strength was measured with two tests (1RM and MVC) before and after training. Integrated electromyography (IEMG) also was measured. Unilateral isotonic and isometric resistance training significantly (p≤0. 05) increased 1RM، MVC and IEMG in the trained and contra lateral untrained limbs، but no significant changes occurred in any variables in the control group. Results of IEMG changes، only showed significant differences between isotonic and control groups. In the view of the resistance exercise intensity and rate of cross education in each groups، it seems isotonic resistance exercise training may be useful than isometric type in rehabilitation program.