STUDY DESIGN: Comparative, repeated-measures study. OBJECTIVES: To examine the effects of an abdominal drawing-in maneuver (ADIM) using a pressure biofeedback unit on electromyographic (EMG) signal amplitude of the hip and back extensors and the angle of anterior pelvic tilt during hip extension in the prone position. BACKGROUND: Prone hip extension is a commonly used position for testing hip extensors strength and performing hip extension exercises. Performing an ADIM during hip extension exercise in prone may reduce the activity of erector spinae and angle of anterior pelvic tilt and increase the activity of hip extensors. METHODS: Twenty ablebodied volunteers (10 male, 10 female) aged 19 to 26 years (mean ± SD, 22.3 ± 3.4 years) were recruited for this study. The EMG signal amplitude and angle of anterior pelvic tilt were measured during prone hip extension with and without performing an ADIM. Surface EMG signal was recorded from the erector spinae, gluteus maximus, and medial hamstrings. Kinematic data for anterior pelvic tilt were measured using a motion analysis system. Data were analyzed using 2-way ANOVAs. RESULTS: When performing an ADIM during hip extension exercises done in a prone position, the EMG signal amplitude decreased significantly in the erector spinae (mean ± SD, 49 ± 14 %MVIC versus 17 ± 12 %MVIC, P‹.001), and increased significantly in both the gluteus maximus (mean ± SD, 24 ± 8 %MVIC versus 52 ± 15 %MVIC, P‹.001) and medial hamstrings (mean ± SD, 47 ± 14 %MVIC versus 58 ± 20 %MVIC, P = .008). The angle of anterior pelvic tilt decreased significantly during prone hip extension with an ADIM (mean ± SD, 10° ± 2° versus 3° ± 1°, P‹.001). CONCLUSIONS: Based on these findings, an ADIM could be used as an effective method to disassociate erector spinae activation from gluteus maximus and medial hamstrings during prone hip extension exercise.

J Orthop Sports Phys Ther. 2007;37(6):320-324, Epub 15 March 2007. doi:10.2519/jospt.2007.2435

KEY WORDS: electromyography, low back, lumbar spine, lumbar stabilization