Postural Cueing to Increase Lumbar Lordosis Increases Lumbar Multifidus Activation During Trunk Stabilization Faercises: Electromyographic Assessment Using Intramuscular Electrodes

STUDY DESIGN: Controlled laboratory study, repeated-measures design. BACKGROUND: Diminished multifidus activation and cross-sectional area are frequent findings in persons with low back pain. Increasing lumbar lordosis has been shown to increase activation of the multifidus with a minimal increase in activation of the long global extensors during unsupported sitting. OBJECTIVES: To examine the influence of postural cueing to increase lumbar lordosis on lumbar extensor activation during trunk stabilization exercises. METHODS: Thirteen asymptomatic participants (9 male, 4 female) were instructed to perform 6 trunk stabilization exercises using a neutral position and increasing lumbar lordosis. Electrical activity of the deep multifidus and longissimus thoracis was recorded using fine-wire intramuscular electrodes. The mean root-mean-square of the electromyography (EMG) signal obtained during each exercise was normalized to a maximum voluntary isometric contraction (MVIC). A 2-way, repeated-measures analysis of variance (posture by exercise) was performed for each muscle. RESULTS: When averaged across the 6 exercises, postural cueing to increase lumbar lordosis resulted in greater multifidus EMG activity compared to performing the exercises in a neutral posture (35.3% +/- 15.1% versus 29.5% +/- 11.2% MVIC). No significant increase in longissimus thoracis EMG activity was observed when exercising with cueing to increase lumbar lordosis. CONCLUSION: This study suggests that postural cueing to increase lumbar lordosis during trunk stabilization exercises may better promote multifidus activation than traditional stabilization exercises alone. Future studies are needed to determine whether increasing lumbar lordosis improves multifidus activation in persons with low back pain.