Date of Award

Spring 2005

Document Type


Degree Name

Master of Science in Education (MSEd)


Human Movement Sciences


Athletic Training

Committee Director

Bonnie Van Lunen

Committee Member

Martha Walker

Committee Member

James Onate

Call Number for Print

Special Collections LD4331.E44 W48 2005


The purpose of this study was to determine EMG activity of the hip stabilizers, thigh, and core muscles during various squatting exercises in order to better appreciate the contribution of the core and thigh during weight bearing functional activity. Surface EMG electrodes were placed over the rectus abdominis (RA), internal oblique (IO), external oblique (EO), erector spinae (ES), vastus medialis (VM), biceps femoris (BF), and gluteus medius (GM). The right leg was used for any single leg exercises perforn1ed. Each subject performed three double leg and three single leg un-weighted squats to 60 degrees of knee flexion on a stable surface, and then repeated the same squats on an unstable surface. Twenty-six recreationally active subjects (10 males, age= 21.9 ± 3.3 yrs, height= 177.5 ± 6.8 cm, mass= 79.7 ± 13.8 kg; 16 females, age= 22.5 ± 4.2 yrs, height= 168.6 ± 5.9 cm, mass= 68.9 ± 10.1 kg), who were free of lower extremity, back, or abdomen injury within the past six months, volunteered to participate in this study. Recreationally active was defined as participating in at least 20 minutes of athletic activity three or more times weekly. A 16.4" x 20" x 2.5" AIREX foam pad was used as the unstable surface. Seven MA-110 surface electrodes with preamplifiers from Motion Lab Systems, Inc (Motion Lab Systems, Inc., Baton Rouge, LA) attached to a DataQ acquisition board had a sampling rate of 1000Hz. Average root mean square (RMS) of muscle activity was found over 1000 milliseconds prior to reaching 60 degrees of knee flexion over the course of the three trials for each exercise and was used as a percentage of maximal voluntary isometric contraction (MVIC) for each muscle. EMG data were analyzed using both a 2 x 2 x 4 ANOVA (core) and a 2 x 2 x 2 x 3 ANOVA (thigh) in which the independent variables were gender (thigh only), surface, squat type, and muscle, and the dependent variable was the RMS measurement. Statistical significance was set at p


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