Clinical biomechanics
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Clinical biomechanics · Apr 1996
Quantitative intramuscular myoelectric activity of quadratus lumborum during a wide variety of tasks.
Intramuscular fine-wire electrodes monitored the electromyographic activity of quadratus lumborum in four young adults. A wide variety of tasks were performed including flexion tasks, lateral bending, twisting, extension, and lifting tasks. Heavy lifts of barbell weights up to 70 kg activated the quadratus lumborum 74% of their maximum on average while surface recording of erector spinae (L(3)) were only 62% of their maximum activation. ⋯ Furthermore, it increased activation in response to increasing compression in static upright standing postures. RELEVANCE:--Electromyographic evidence, together with architectural features make the quadratus lumborum a better stabilizer of the spine than psoas. Use of horizontal 'side support' exercise to train this muscle would appear to be a wise choice.