Enhanced balance strategy after inspiratory muscle training in patients with COPD, an interim analysis

Abstract

Background: Falls are highly prevalent in patients with COPD. Particularly those with low maximal inspiratory pressure (PImax) predominantly use ankle muscle proprioception to maintain balance. This strategy is assumed to be suboptimal as it is associated with a larger postural sway.

Aim: To study the effect of (sham) inspiratory muscle training (IMT) on ankle proprioceptive use during balance control in patients with COPD.

Methods: Fifteen patients with COPD (66±5 yr, FEV1/FVC 53±15%) completed 8 weeks of IMT, either at 50% (n= 11; IMT) or 10% of PImax (n= 4; sham). Before and after (sham) IMT, PImax, centre of pressure displacement in response to ankle vibration in standing and functional balance (Mini-BESTest) were measured.

Results: After 8 weeks, the IMT group showed increased PImax (+Δ19cmH₂O) compared to the sham group (+Δ6cmH₂O) (F= 4.13, p= 0.065). Also, the IMT group showed significantly less postural response (17±9mm) on ankle vibration compared to the sham group (36±14mm) (F= 1.90, p= 0.010), not seen at baseline (F= 0.03, p= 0.122), although no group X time interaction effect was found (F= 1.90, p= 0.192). Mini-BESTest scores showed a trend toward improvement from baseline (IMT 24.2±2.4; sham 24.3±2.5) to 8 weeks of training (IMT 25.1±2.8; sham 23.8±2.6) (F= 2.84; p= 0.120).

Conclusion: This interim analysis on 15 of 24 planned subjects suggests that 8 weeks of IMT decreases reliance on ankle proprioception in patients with COPD, suggestive of enhanced balance control. Also, a trend toward improved functional balance performance was found after IMT, but not reaching the minimal clinically important difference.