Effect of two acute static stretching durations of the rectus femoris muscle on quadriceps isokinetic peak torque in professional soccer players

Abstract

While athletes routinely perform warm-up and stretching exercise, it has been suggested that prolonged stretching, immediately prior to an activity, might affect negatively the force production. Fifteen professional soccer players participated in the study to examine whether a routine duration of acute static stretching may account for losses in isokinetic peak torque production. All participants performed two static stretching protocols on the rectus femoris muscle tendon unit (MTU), at different training sessions, with a week interval. The first stretching protocol was performed four times for 15 s (4 x 15 s), and the second 32 times for 15 s (32 x 15 s). Range of motion (ROM) was determined during knee flexion, with a pendular Myrin flexometer. The peak torque of the dominant leg extensors was measured on a Cybex Norm dynamometer at 60, 90, 150, 210 and 270°/s angular velocities. The 2 × 2 analysis of variance showed that peak torque remained unchanged, following the total static stretching for 60 s in all angular velocities, while it decreased in all angular velocities, following a total static stretching for 8 minutes (p < 0.001). The findings suggest that an acute static stretching exercise of short duration, as performed by soccer players, during warming up procedures, does not produce decreases in peak torque, compared to multiple stretches of an 8 minute long duration.