Acute effects of static stretching on the knee joint position sense of soccer players: A crossover randomized controlled trial.

BACKGROUND

Static stretching (SS) is recommended to increase short-term flexibility and to reduce the risk of muscle/tendon injuries. However, impairments on muscle performance are also reported. Regarding its effect on the knee joint-position sense (JPS), conclusions remain inconclusive.

AIM: To investigate the acute effects of two different durations of SS on the knee JPS of soccer players.

METHODS

This 3-period block-randomized controlled crossover trial included 17 male soccer players, aged 18-30 years, with normal knee range of motion and without history of lower limb injuries in the last 6 months. All participants performed 3 conditions: two experimental conditions of SS of the quadriceps and hamstrings muscles, for 30s or 90s; and a control condition (rest). Knee JPS of the dominant limb was assessed before and immediately after the conditions for the range of 45° of knee flexion by active repositioning, using a video camera and markers. JPS was expressed as absolute, relative and variable angular errors.

RESULTS

No significant differences in the errors were found between the assessment conducted before or after the SS interventions or Control (p > 0.05). However, intergroup comparisons revealed a significantly higher absolute angular error after the SS of 90s compared to Control (p = 0.003). Also, significantly higher relative errors after the SS of 90s were found compared to Control (p = 0.006) and SS of 30s (p = 0.004).

CONCLUSION

SS of the quadriceps and hamstrings appears to have no effects on the knee JPS, regardless of the duration of the SS.