Lower-extremity muscle activation during the star excursion balance tests

Objective: To identify integrated EMC II-EMC) activity of 6 lower-extremity muscles during the 8 Star Excursion Balance Test (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 a nd maximally reach with the contralateral foot along each of 8 lines extend ing from a common axis at 45 degrees intervals. Measures: I-EMG activity of the vastus medialis obliquus (VMO), vastus late ralis (VL), medial hamstring (MH), biceps femoris (BF), anterior tibialis ( AT), and gastrocnemius. Results: Significant differences were found in all muscles (P (.)< .05) exc ept the gastrocnemius (P = .08). VMO and VL activity tended to be greatest with anteriorly directed excursions, whereas the MH and BF activity were gr eatest with posteriorly directed excursions. AT activity was lowest with th e lateral excursion. Conclusions: Performance of the different SEBTs results in different lower- extremity muscle-activation patterns.