Comparison of quadriceps and hamstrings activation ratio between healthy and anterior cruciate ligament reconstructed subjects

The aim of this study was to compare the ratio of activation of the vastus lateralis (VL) and biceps femoris (BF) muscles between healthy (CG) and anterior cruciate ligament reconstructed (ACL-R) subjects during gait. Nineteen subjects, ten from GC and nine from ACL-R, participated in the study. VL and BF activity was captured and the VL/BF ratio was obtained by dividing each point on the curve of the vastus lateralis and biceps femoris. This ratio was compared between the two groups using an unpaired t test (a = 0.05). Differences between the two groups were found (p <;0.05) in the initial double limb stance phase, representing the initial 10% of the gait cycle. There were no differences for the other gait phases (p <;0.05). It is concluded that the differences in ratio between knee extensors and flexors persist even one year after ACL reconstructions. These differences may be related to protective strategies to avoid excessive stress caused by the anterior shear of the tibia over the femur as a function of excessive vastus lateralis contraction. However, it is unknown whether this strategy has any relation to the risk of developing knee osteoarthritis in the future.