Effects of Different Volitional Preemptive Abdominal Contraction Strategies on Lumbar Multifidus Co-activation in Adults with Low Back Pain

Abstract

Introduction and purpose: Low back pain (LBP) is the most common musculoskeletal complaints among adults of working age population Lumbar multifidi (MF) atrophy and other deep core muscles delayed onset and decreased activation have been identified in the adults with LBP Co-contraction of deep core muscles is critical for sustaining spinal stability while the MF is difficult to be specifically activated Lumbar MF has proved to be co-activated during the abdominal drawing in healthy young adults However it is unknown whether such volitional preemptive abdominal contraction (VPAC) strategy is still effective in the adults with LBP Whether other type of VPAC strategy (i e abdominal push out) could also induce the MF co-activation and whether such responses might be affected by the postural conditions remain unknown Thus the purpose of this study was to investigate the effects of different VPAC strategies on co-activation of the lumbar MF in different postural conditions in the adults with LBP Methods: Thirty adults with LBP participated in this study Thickness and activity of the abdominal muscles including external obliques (EO) internal obliques (IO) and transversus abdominis (TrA) along with the MF at the L4/L5 and L5/S1 level were measured using the ultrasound imaging (USI) and surface electromyography (EMG) during 3 VPAC strategies (no-VPAC NO; abdominal draw-in AD; and abdominal push-out AP) under 3 postural conditions (lying upright standing and single leg standing) Two trials were obtained for each condition 3x3 repeated measures ANOVAs were used to compare the differences between VPAC strategies (NO vs AD vs AP) and postural conditions (lying vs quiet standing vs single leg standing) for the USI and EMG variables Post hoc analysis was conducted as indicated Results: Significant increases in muscle thickness change and muscle activity were found in the L4/L5 and L5/S1 MF during both VPAC strategies than the NO strategy in all postural conditions Higher preferential activation ratios of L4/L5 and L5/S1 MF were found during the AP than the AD strategy while higher preferential activation ratios of TrA were found during the AD than the AP strategy Conclusions: The VPAC strategies were effective on deep stabilizing spinal muscles activation including both TrA and MF in the adults with LBP despite postural challenges The TrA recruitment was more evident during the AD strategy while more obvious MF recruitment during the AP strategy Future studies should examine the long-term effects of the VPAC strategies on the lumbar MF training in patients with LBP

Date of Award	2019
Original language	English
Supervisor	Yi-Ju Tsai (Supervisor)