Although several studies have investigated the acute effect of static stretching exercises, the duration of exercises that negatively affects performance has not been ascertained. This study was conducted to determine the acute effect of different static stretching durations on quadriceps isometric and isokinetic peak torque production. The 50 participants were randomly allocated into five equivalent sized groups and were asked to perform a stretching exercise of different duration (no stretch, 10-second stretch, 20-second stretch, 30-second stretch, and 60-second stretch). The knee flexion range of motion and the isometric and concentric isokinetic peak torques of the quadriceps were measured before and after a static stretching exercise in the four experimental groups. The same parameters were examined in the control group (no stretch) without stretching, before and after a 5-minute passive rest. There were no significant differences among groups before the experimentation regarding their physical characteristics and performances (P > 0.05). These results reflect the different groups' homogeneity. Significant knee joint flexibility increases (P < 0.001) and significant isometric and isokinetic peak torque reductions (P < 0.05-0.001) have been shown to occur only after 30 and 60 seconds of quadriceps static stretching. Stretching reduced isometric peak torque by 8.5% and 16.0%, respectively. Concerning isokinetic peak torque after 30 and 60 seconds of stretching, it was reduced by 5.5% vs. 11.6% at 60 degrees/s and by 5.8% vs. 10.0% at 180 degrees/s. We suggest that torque decrements are related to changes of muscle neuromechanical properties. It is recommended that static stretching exercises of a muscle group for more than 30 seconds of duration be avoided before performances requiring maximal strength.

Although warm-up and stretching exercises are routinely performed by gymnasts, it is suggested that stretching immediately prior to an activity might affect negatively the athletic performance. The focus of this investigation was on the acute effect of a protocol, including warm-up and static and dynamic stretching exercises, on speed during vaulting in gymnastics. Eleven boys were asked to perform three different protocols consisting of warm-up, warm-up and static stretching and warm-up and dynamic stretching, on three nonconsecutive days. Each protocol was followed by a “handspring” vault. One-way analysis of variance for repeated-measures showed a significant difference in gymnasts’ speed, following the different protocols. Tukey’s post hoc analysis revealed that gymnasts mean speed during the run of vault was significantly decreased after the application of the static stretching protocol. The findings of the present study indicate the inhibitory role of an acute static stretching in running speed in young gymnasts.

Previous gender comparisons of muscle performance have overlooked differences in absolute strength and have studied men and women at similar percentages of their maximal voluntary contraction (MVC). The purpose of this study was to examine agonist and antagonist muscle activation during submaximal fatigue, in men and women matched for strength. We compared plantar flexion muscle performance during a 10-min submaximal (20% MVC) fatigue protocol in ten healthy men and ten healthy women matched for plantar flexor MVC torque output [156.0 (17.6) N m for men and 152.9 (21.7) N m for women, mean (SD), P>0.05]. The results showed that after the fatigue protocol the torque output and the averaged electromyogram (EMG) amplitude of all muscles examined decreased significantly in both genders. The submaximal torque was sustained at the requested level (20% MVC) during the fatiguing contraction by increasing motor unit activity as indicated by the EMG. However, the post hoc tests revealed no significant differences between the two genders in any of the aforementioned tests. The similarity of agonist and antagonist muscle activation during a sustained submaximal contraction in both men and women suggests that the differences in fatigability between the two genders are diminished when the absolute force production is similar.

Our study showed that elite gymnasts share four common morphological characteristics on MRI that deviate from normal. These findings were in asymptomatic subjects; hence, radiologists and sports physicians should be aware of them in order to avoid unnecessary treatment.

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