Lower-Extremity Muscle Activation during the Star Excursion Balance Tests

Objective: To identify integrated EMG (I-EMG) activity of 6 lower-extremity muscles during the 8 Star Excursion Balance Tests (SEBTs). Design and Setting: Repeated measures, laboratory setting. Subjects: 10 healthy young adults. Interventions: The SEBTs require the subject to balance on the stance leg and maximally reach with the contralateral foot along each of 8 lines extending from a common axis at 45° intervals. Measures: I-EMG activity of the vastus medialis obliquus (VMO), vastus lateralis (VL), medial hamstring (MH), biceps femoris (BF), anterior tibialis (AT), and gas-trocnemius. Results: Significant differences were found in all muscles ( P < .05) except the gastrocnemius ( P = .08). VMO and VL activity tended to be greatest with anteriorly directed excursions, whereas the MH and BF activity were greatest with posteriorly directed excursions. AT activity was lowest with the lateral excursion. Conclusions: Performance of the different SEBTs results in different lower-extremity muscle-activation patterns.