Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease

Abstract

Introduction: Balance 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.

Methods: Center 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.

Results: Individuals 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).

Conclusions: Individuals 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.

Conflict of interest statement

Competing Interests: AKM acknowledges a beneficial interest in an inspiratory muscle training product (POWERbreathe International Ltd.) in the form of a share of license income to the University of Birmingham and Brunel University. She also acts as a consultant to POWERbreathe International Ltd. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. LJ, SB, KC, MP, CB, WJ, MD and TT declare that they have no competing interests.

Figures

Figure 1. Experimental set-up.

Standing on unstable support surface on force plate with ankle and back muscles vibration and vision occlusion.

Figure 2. Postural stability.

Raw data of center of pressure (CoP) displacement of an individual with COPD and an age/gender-matched healthy individual while standing on unstable support surface without vision for 30 seconds. Positive values indicate an anterior body sway, negative values indicate a posterior body sway.

Figure 3. Proprioceptive control strategy.

Center of pressure displacement (mean ± SD) in the control group (black) and COPD group (white) during vibration on ankle muscles, back muscles, and simultaneously on ankle and back muscles. Positive values indicate an anterior body sway, negative values indicate a posterior body sway.

Figure 4. Relative proprioceptive weighting.

Individual (left) and mean ± SD (right) relative proprioceptive weighting (RPW) ratios in the COPD group (white) and age/gender-matched control group (black). Higher values correspond to higher reliance on ankle muscle proprioception; lower values correspond to higher reliance on back muscle proprioception.