Contraction of the abdominal muscles associated with
movement of the lower limb. Phys Ther 1997 Feb;77(2):132-42; discussion 142-4
Hodges PW, Richardson CA
Department of Physiotherapy, University of Queensland, Brisbane, Australia.
BACKGROUND AND PURPOSE: Activity of the trunk muscles is essential
for maintaining stability of the lumbar spine because of the unstable structure
of that portion of the spine. A model involving evaluation of the response of
the lumbar multifidus and abdominal muscles to leg movement was developed to
evaluate this function. SUBJECTS: To examine this function in healthy persons, 9
male and 6 female subjects (mean age = 20.6 years, SD = 2.3) with no history of
low back pain were studied. METHODS: Fine-wire and surface electromyography
electrodes were used to record the activity of selected trunk muscles and the
prime movers for hip flexion, abduction, and extension during hip movements in
each of those directions. RESULTS: Trunk muscle activity occurring prior to
activity of the prime mover of the limb was associated with hip movement in each
direction. The transversus abdominis (TrA) muscle was invariably the first
muscle that was active. Although reaction time for the TrA and oblique abdominal
muscles was consistent across movement directions, reaction time for the rectus
abdominis and multifidus muscles varied with the direction of limb movement.
CONCLUSION AND DISCUSSION: Results suggest that the central nervous system deals
with stabilization of the
spine by contraction of the abdominal and
multifidus muscles in anticipation of reactive forces produced by limb movement.
The TrA and oblique abdominal muscles appear to contribute to a function not
related to the direction of these forces.
PMID: 9037214 UI: 97188942