The effects of two different stretching exercises together with plyometric training on EMG values and some physiological parameters

The purpose of this study was to examine the chronic effects of two differentstretching exercises with plyometric training on flexibility, vertical jump performans,knee extensor strength and root mean square values. Thirty two volunteeredsubjects, ranging in age from 19 to 25 years, were randomly assigned to one ofthree groups (Contract-Relax PNF group n=12, static stretch group n=11, controlgroup n=9).Latissimus dorsi muscle and gluteus maximus, hamstring, quadriceps vetriceps surae muscles in both legs were stretched by contract-relax PNF stretchingand static stretching 3 days per week for 6 weeks. Third group, which is a controlgroup did not do any stretching.All measurements were taken before and after 6 weeks of exercise program.Flexibility of the hamstring muscles was determined by sit and rich test protocol.Vertical jump performances were assessed by using static jump test procedure. Legstrength performances were assessed by using leg and back dynamometer. Root meansquare values were recorded from vastus lateralis and vastus medialis muscles bysurface electrode method.For statistical analysis among three groups, Kruskal-Wallis test procedureswere performed with the averaged values of the dependent variables (flexibility,vertical jump performance, knee extensor strength and root mean square values).When there was signifıcant main effect differences, those differences were furtheranalyzed by Mann-Whitney U Test and Wilcoxon Signed Ranks Test and the alphalevel was set at p≤0.05.The results of the study indicated that both of type of stretching exercisessignificantly improved hamstrings flexibility, vertical jump performance, legextensor strength values (p<0.05). Also, the root mean square values of vastuslateralis and vastus medialis were significantly improved from pretest to posttest.Key Words: Plyometrik training, flexibility, vertical jump performans, kne extensorstrength, root mean square values.