Anticipatory Effect on Lower Extremity Muscle Recruitment and Activation Patterns During Single Leg Drop Tasks.

OBJECTIVES: To examine the anticipatory effect on lower extremity muscle activation during single leg drop landing and jumping. METHODS: Seventeen healthy males performed single leg drop landing and jumping, under conditions manipulating the subsequent movement after landing. Participants performed the anticipated condition (subsequent movement-land/jump-was preplanned), followed by the unanticipated condition (subsequent movement was given via visual signals). Electromyography of the gluteus medius (GM), rectus femoris (RF), vastus medialis (VM), semitendinosus (ST), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (MG) were obtained. The time of onset, time-to-peak amplitude (from onset or initial contact), and peak amplitude were compared (p<0.05). RESULTS: Overall, under the unanticipated condition, the time (0 = initial contact) of onset of RF (-101 ms vs. -245 ms), TA (-116 ms vs. -232 ms) and MG (-122 ms vs. -180 ms) and time-to-peak amplitude (from initial contact) of RF (223 ms vs. 13 ms), ST (111 ms vs. -9 ms), and MG (79 ms vs. -41 ms for unanticipated and anticipated, respectively) were delayed compared to anticipated condition. CONCLUSIONS: When visual cues were unanticipated, participants demonstrated delayed and redistributed muscle activation timing during single leg landing and jumping.