Annual Meeting (36th) of the International Society for the Study of the Lumbar Spine location:Miami date:4-8 May 2009
Acute inspiratory muscles fatigue induces a rigid proprioceptive postural control strategy in persons with and without low back pain.
People with recurrent low back pain (LBP) use a more rigid proprioceptive postural control strategy than control subjects during postural perturbations. Recent evidence suggests that respiratory movements create postural instability in people with LBP. Little is known about the role of the respiratory muscles in postural control strategies, but can be studied by inducing acute inspiratory muscles fatigue (IMF). The objective of this study was to determine postural stability and proprioceptive postural control strategies of healthy subjects and subjects with recurrent LBP during acute IMF.
Postural control was evaluated in 16 people with LBP and 12 healthy controls, both before and after acute IMF. Center of pressure (CoP) displacement was determined on a force plate to evaluate postural stability. Postural control strategies were examined during vibration of the triceps surae muscles or lumbar paraspinal muscles, whilst standing on both a stable and unstable support surface and without vision. Proprioceptive postural control strategies were determined by examining the ratio of mean CoP displacement measured during of triceps surae muscles vibration to that measured during lumbar paraspinal muscles vibration.
After IMF healthy subjects showed a significantly larger sway compared to the unfatigued condition whilst standing on an unstable support surface (p<0.05). They showed an increased reliance on proprioceptive signals from the ankles, which resembled the postural control strategy used by people with LBP (p<0.05). Subjects with LBP showed that same ankle steered postural control strategy in the unfatigued and IMF states (p>0.05).
After IMF healthy subjects use a rigid proprioceptive postural control strategy, rather than the normal ‘multi-segmental’ control, which is similar to people with LBP. This results in decreased postural stability. These findings suggest that the inclusion of inspiratory muscle training into a postural control coaching may assist in the management of recurrent LBP.