Acute effects of two different stretching techniques on soccer players vertical jump performance and emg values

The purpose of this study was to examine the acute effects of two different stretching techniques on soccer players vertical jump performance (maximal anaerobik force), and EMG (root mean square) values. Twenty-one soccer players volunteered, their ranging mean age was 23.26 ± 1.76 years. The subjects were randomly assigned to three groups (Contract-Relax PNF group n=7, static stretch group n=7, control group n=7).All participants performed 5 minutes jogging as a warm-up routine. Then gastrocnemius, gluteus maximus, hamstring and quadriceps muscles in both legs were stretched by contract-relax PNF stretching and static stretching for 4 times with 30 seconds. The conrol group did not do anything at this time.Vertical jump and EMG root mean square values were measured before and after the stretching. Counter movement jump test protocol was used to determine the vertical jump height. EMG (root mean square) values were recorded from vastus medialis and vastus lateralis muscles by surface electromyography method.The three groups pre-posttest values were compared by utilizing Wilcoxon Signed Rank Test. The mean value differences between the three groups were determined by Kruskal-Wallis statatistics, for this statistics the dependent variables were vertical jump performance (maximal anaerobic force) and EMG (root mean square). Moreover, the Mann-Whitney U test follow-up procedure was used to determined group mean differences.As a result of the study it was found out that for both experimental group?s the vertical jump performance (maximal anaerobik force) mean values dropped statistically significantly (p < 0.05). Kruskal- Wallis test results indicated that the differences among groups on jump performance were statistically different (p <0.05). The post-hoc results revealed that there was only statistical differences among the experimatel groups when compared with the control group, no significant differences were observed between the experimantel groups mean values.In conclusion, this study showed that applied static and PNF streching exercises decreased maximal anaerobic force values. Similarly vastus medialis and vastus lateralis root mean square values decreased.Key Words: Counter movement jump, PNF stretching, Static stretching, , EMG, root mean square.