The effect of stretching duration on the lower-extremity flexibility of adolescent soccer players

The purpose of this study was to examine the effects of static stretching duration, and multiple stretches of different duration, on the lower-extremity range of motion (ROM), while controlling the total amount of the time spent in a stretching session, in adolescent soccer players. Fifteen adolescent soccer players with average age of 16.0±0.5 years, height of 176.0±4.0 cm, body mass of 68.6±3.3 kg and years of training of 5.0±0.5 participated in the study. Subjects performed three static stretching protocols each lasting for 30 s, in separate training sessions. The first stretching protocol was performed once for 30 s (1×30 s), the second twice for 15 s (2×15 s) and the third 6 times for 5 s (6×5 s). The first protocol comprised the control treatment while the two others, the experimental treatment. ROM was determined during hip flexion, extension and abduction, knee flexion and ankle dorsiflexion for right and left side of the body, using a flexometer and a goniometer. A mixed within-and between-subjects analysis of variance with repeated measures revealed similar ROM values for both sides of all measured joints. No significant differences were found between the stretching protocols. Further statistical analysis of the data indicated significant (P<0.01 to P<0.001) improvements after the stretching exercises in all flexibility protocols. The findings suggests that one 30-s static stretch of the lower-extremity muscles produced the same effect as two 15-s or six 5-s stretches during a flexibility-training session involving adolescent soccer players.