Comparision the timing of lower limb muscles activity in the stance phase of running between athletes with reconstructed anterior cruciate ligament and healthy

after reconstructing the anterior cruciate ligament, in order to prevent re-injury of the ligament, evaluation of neuromuscular function is of clinical importance in coordinating the onset time and time to peak of lower limb's muscles activity.

Therefore the purpose of this study was to compare the timing of muscles activity in the stance phase of running between athletes with reconstructed anterior cruciate ligament and healthy subjects.

This study was a semi-experimental and applied type. 10 athletes with reconstructed anterior cruciate ligament who at least one year had passed since their surgery, as experimental group and 10 healthy subjects as control group of Hamedan city were volunteered to participate in the study. The control group in terms of age, height and weight were homological with experimental group. surface electromyography system was used to quantify the onset time and time to peak of lower limb's muscles activity. multivariate MANOVA with a significance level of P< 0.05 was used for statistical analysis.

In experimental group, the onset of the activity in tibialis anterior, medial gastrocnemius, vastus medialis, vastus lateralis, gluteus medius (P= 0.001) as well as the time to peak in tibialis anterior, vastus lateralis, vastus medialis, gluteus medius, semitendinosus (P= 0.001) and biceps femoris (P= 0.045) were delayed.

During the stance phase of running, experimental group displayed a delay on the activation onset, and a longer time to peak in the lower limb's muscles. It is not clear if these changes are due to a neuromuscular adaptation or proprioception related damage. A more comprehensive study is recommended to clarify this aspect. It is recommended to assess the possible link between this delay with reoccurrence of anterior cruciate ligament rupture.