title: EMG Analysis of Core and Thigh Musculature Contribution During Double and Single Leg Squats on Both Stable and Unstable Surfaces
Creators: name: Whitehead, Julie M.
Publisher: name: Old Dominion University
publisherIdentifier: https://ror.org/04zjtrb98
publisherIdentifierScheme: ROR
Year: 2005

description: 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<0.05. Within the core the internal oblique muscle was the most active during all activities (p=.000) followed by the erector spinae, external oblique, and the rectus abdominis. The single leg stance activity generated higher overall muscle activity than the double leg (p = .021). Within the thigh the vastus medialis produced the greatest muscle activity (p = .000) followed by the gluteus medius and biceps femoris. The single leg squat produced greater activity than the double leg squat (p = .000) and the vastus medialis activity was significantly higher for the single leg versus the double leg squat (p = .000). The vastus medialis for the females was significantly more active than the biceps femoris for the males and females (p = .000). The inclusion of single leg squat in a functional training program for the thigh (vastus medialis) and hip (gluteus medius) muscles is recommended based on observed muscle activity patterns. Additionally the single leg squat recruits the core musculature better than the double leg squat. These exercises are beneficial in recruitment of key abdominal stabilizers and thigh musculature and therefore should be incorporated into training programs.