ABSTRACT
The purpose of this study was to determine the muscle activity during cutting in female basketball player. Eight female basketball players participated in this study. Each subject was instructed to do two steps of approach run, and change direction to the right laterally. Cutting motion is divided two into a phase: knee joint <i>flexion phase</i> and <i>extension phase</i>. Bipolar surface EMG electrodes, spaced 30 mm apart and oriented parallel to the muscle fascicles were secured over the muscle bellies of the Vastus Medialis (VM), Vastus Lateralis (VL), Biceps Femoris (BF), and Semimembrasosus (SM) musculature. EMG recordings were employed to measure the ratio of activation between the medial-to-lateral Hamstring and Quadriceps, and Hamstring and Quadriceps. All the subject had 10-15 degrees knee angle during cutting. In <i>flexion phase</i>, Quadriceps acted more significantly than Hamstring (p<0.05). Moreover, VM activity acted larger than VL, and BF activity acted larger than SM in each phases (p<0.05) All the subject reveal a similar pattern: Quadriceps act largely in <i>flexion phase</i>, which may increase anterior tibial shear forces, strain on the anterior cruciate ligament. Moreover, medial muscle activity acted larger than lateral muscle in Quadriceps, and lateral muscle activity acted larger than medial muscle in Hamstring in each phase. All the subject had 10-15 degree knee angle during cutting, therefore, a variation in lateral and medial muscle may trigger knee valgus.