implications for anterior cruciate ligament injury. S Colby, A Francisco, ... lateralis, vastus medialis oblique, rectus femoris, biceps femoris and medial hamstrings.
Electrornyographic and kinematic analysis of cutting maneuvers: implications for anterior cruciate ligament injury S Colby, A Francisco, M Finch, A Beutler & W Garrett* Division of Orthopaedics and Sports Medicine, Durham, USA
Objective: The objective of this study was to qualitatively characterize the muscle activation of the quadriceps and hamstrings, as well as l~nee flexion angle during the eccentric motion of athletic maneuvers most involved with ACL injury: sidestep cutting, cross-cutting, stopping and landing. Fifteen healthy collegiate and recreational athletes (age = 22.2 + 1.70 years, stature = 176.11 _+ 9.34 cm, and mass = 70.45 + 11.23 kg) performed the four movements while knee angle and EMG activity (surface electrodes) of the vastus lateralis, vastus medialis oblique, rectus femoris, biceps femoris and medial hamstrings (semimembranosus/semitendinosus) were recorded.
Method: Muscle activity and knee joint angles were studied during various athletic maneuvers to assess implications for anterior cruciate ligament (ACL) injury.
Results: The results of this study indicate that there is high level quadriceps activation beginning prior to heel strike and pealdng in mid-eccentric motion for these movements thought to be related to non-contact ACL injuries. In these maneuvers, the level of quadriceps activation frequently exceeded that seen in a m a x i m u m isometric contraction. Furthermore, there was submaximal activity in the hamstrings at and following heel strike. Coupled with this minimal hamstring activation and a low angle of l~ee flexion at heelstrike and during eccentric contraction, forces generated by the quadriceps muscles at the lrmee could produce significant anterior force to tear the ACL.
Conclusions and significance: Strengthening programs and different techniques of performing these maneuvers may be developed to help reduce the incidence of ACL injuries.
