Effects of lumbar stabilization using a pressure biofeedback unit on muscle activity and lateral pelvic tilt during hip abduction in sidelying.
Level 3 - non-randomized controlled study
Non-randomized within-subject comparative repeated-measures study
PubMed 17084119 · doi:10.1016/j.apmr.2006.08.327
What was done
Eighteen healthy volunteers (9 men, 9 women) performed hip abduction in a sidelying position under two conditions: preferred hip abduction and hip abduction with lumbar stabilization guided by a pressure biofeedback unit. Surface electromyography was recorded from the quadratus lumborum, gluteus medius, internal oblique, external oblique, rectus abdominis, and multifidus muscles. Lateral pelvic tilt angle was measured using a motion analysis system, and differences were evaluated using a 2 (condition) x 2 (sex) repeated-measures analysis of variance.
What was found
With lumbar stabilization, quadratus lumborum activity decreased from 60.39% ± 15.62% to 27.90% ± 13.03% of maximum voluntary isometric contraction (MVIC), while gluteus medius activity increased from 25.03% ± 10.25% to 46.06% ± 21.20% MVIC and internal oblique activity increased from 24.25% ± 18.10% to 44.22% ± 20.89% MVIC. Lateral pelvic tilt angle decreased from 13.86° ± 4.66° to 5.55° ± 4.16°. Women exhibited significantly higher MVIC percentages than men in the gluteus medius, external oblique, and rectus abdominis.
Why it matters
Using pressure biofeedback for lumbar stabilization during sidelying hip abduction effectively reduces compensatory pelvic tilt and quadratus lumborum substitution while enhancing target gluteus medius recruitment.
Limits
The sample was small (n = 18) and limited to healthy, asymptomatic volunteers. The study tested only immediate biomechanical and electromyographic effects during a single laboratory session, without assessing clinical populations, long-term training retention, or pain outcomes.