Persons with recurrent low back pain (LBP) have been observed to have altered proprioceptive postural control. These patients seem to adopt a body and trunk stiffening strategy and rely more on ankle proprioception to control their posture during quiet upright standing. The aim of this study is to determine the effect of changing postural condition (stable and unstable support surface) on postural stability and proprioceptive postural control strategy in persons with recurrent LBP. Postural sway characteristics of 21 persons with recurrent LBP and 24 healthy individuals were evaluated in upright posture with or without standing on "foam" for the conditions as follows: (1) control (no vibration); (2) vibration of the triceps surae muscles; (3) paraspinal muscle vibration; (4) vibration of the tibialis anterior muscles. Vision was occluded in all conditions except for one control trial. All trials lasted 60 s. Vibration (60 Hz, 0.5 mm), as a potent stimulus for muscle spindles, was initiated 15 s after the start of the trial for a duration of 15 s. Persons with recurrent LBP showed significantly different postural control strategies favoring ankle muscle proprioceptive control (ratio closer to 1) instead of paraspinal muscle proprioceptive control (ratio closer to 0) for both standing without foam (ratio ankle muscle/paraspinal muscle control = 0.83) (P < 0.0001) and on foam (ratio ankle muscle/paraspinal muscle control = 0.87; P < 0.0001) compared to healthy individuals (0.67 and 0.46, respectively). It is concluded that young persons with recurrent LBP seem to use the same proprioceptive postural control strategy even in conditions when this ankle strategy is not the most appropriate such as standing on an unstable support surface. The adopted proprioceptive postural control strategy might be effective in simple conditions, however, when used in all postural conditions this could be a mechanism to undue spinal loading, pain and recurrences.

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Optimal postural control is an essential capacity in daily life and can be highly variable. The purpose of this study was to investigate if young people have the ability to choose the optimal postural control strategy according to the postural condition and to investigate if non-specific low back pain (NSLBP) influences the variability in proprioceptive postural control strategies. Young individuals with NSLBP (n = 106) and healthy controls (n = 50) were tested on a force plate in different postural conditions (i.e., sitting, stable support standing and unstable support standing). The role of proprioception in postural control was directly examined by means of muscle vibration on triceps surae and lumbar multifidus muscles. Root mean square and mean displacements of the center of pressure were recorded during the different trials. To appraise the proprioceptive postural control strategy, the relative proprioceptive weighting (RPW, ratio of ankle muscles proprioceptive inputs vs. back muscles proprioceptive inputs) was calculated. Postural robustness was significantly less in individuals with NSLBP during the more complex postural conditions (p < 0.05). Significantly higher RPW values were observed in the NSLBP group in all postural conditions (p < 0.05), suggesting less ability to rely on back muscle proprioceptive inputs for postural control. Therefore, healthy controls seem to have the ability to choose a more optimal postural control strategy according to the postural condition. In contrast, young people with NSLBP showed a reduced capacity to switch to a more multi-segmental postural control strategy during complex postural conditions, which leads to decreased postural robustness.

After 8 wk of high IMT, individuals with LBP showed an increased reliance on back proprioceptive signals during postural control and improved inspiratory muscle strength and severity of LBP, not seen after low IMT. Hence, IMT may facilitate the proprioceptive involvement of the trunk in postural control in individuals with LBP and thus might be a useful rehabilitation tool for these patients.

IntroductionBalance deficits are identified as important risk factors for falling in individuals with chronic obstructive pulmonary disease (COPD). However, the specific use of proprioception, which is of primary importance during balance control, has not been studied in individuals with COPD. The objective was to determine the specific proprioceptive control strategy during postural balance in individuals with COPD and healthy controls, and to assess whether this was related to inspiratory muscle weakness.MethodsCenter of pressure displacement was determined in 20 individuals with COPD and 20 age/gender-matched controls during upright stance on an unstable support surface without vision. Ankle and back muscle vibration were applied to evaluate the relative contribution of different proprioceptive signals used in postural control.ResultsIndividuals with COPD showed an increased anterior-posterior body sway during upright stance (p = 0.037). Compared to controls, individuals with COPD showed an increased posterior body sway during ankle muscle vibration (p = 0.047), decreased anterior body sway during back muscle vibration (p = 0.025), and increased posterior body sway during simultaneous ankle-muscle vibration (p = 0.002). Individuals with COPD with the weakest inspiratory muscles showed the greatest reliance on ankle muscle input when compared to the stronger individuals with COPD (p = 0.037).ConclusionsIndividuals with COPD, especially those with inspiratory muscle weakness, increased their reliance on ankle muscle proprioceptive signals and decreased their reliance on back muscle proprioceptive signals during balance control, resulting in a decreased postural stability compared to healthy controls. These proprioceptive changes may be due to an impaired postural contribution of the inspiratory muscles to trunk stability. Further research is required to determine whether interventions such as proprioceptive training and inspiratory muscle training improve postural balance and reduce the fall risk in individuals with COPD.