Effects of Static Stretching and Playing Soccer on Knee Laxity

Objective: This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint.

Design: Randomized controlled trial.

Setting: University biomechanics laboratory.

Participants: Thirty-one athletes were randomly assigned into a stretching (26.9 6.2 years, 1.77 0.09 m, 67.9 10.7 kg) and a control group (27.9 7.4 years, 1.75 0.08 m, 72.0 +/- 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 +/- 5.6 years, 1.74 +/- 0.10 m, 71.8 +/- 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury.

Interventions: The stretching group performed 4 different static stretching exercises with a duration of 2 x 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes.

Main Outcome Measures: Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention.

Results: There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 +/- 1.6 mm (P <0.0005) and after playing soccer of 1.0 +/- 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups.

Conclusions: Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer.