Postural function of the diaphragm and the effectiveness of 8 weeks inspiratory muscle training in people with chronic obstructive pulmonary disease: a randomized, single-blinded, placebo-controlled trial

Abstract

Participants: A single-blind, randomized, placebo-controlled study design was used. Eleven eligible subjects with COPD were randomized to either an intervention group (n= 8) or a control group with placebo IMT (n= 3) Measurements: all subjects were subjected to twelve different postural tasks Primary outcomes were diaphragm muscle activity (electromyography) and postural balance (stabilometry). Also, functional balance performance and inspiratory muscle function were evaluated before and after the intervention. Results: Postural function of diaphragm was confirmed by both single and repetitive upper limb (UL) movements. For repetitive UL movements a direction-specific tonic contraction was shown, dependent of the breathing mode. IMT was found to significantly increase postural diaphragm activity over time in eight out of twelve trials in the intervention group (p< 0.05). A trend towards, but no overall treatment effect was observed for stabilometric parameters and functional balance performance. Conclusion: Diaphragm activity significantly increased when the postural demand increased in people with COPD. IMT positively influenced the identified postural-related changes in diaphragm activation, but the transfer to improvements in balance was lacking. Further research with a larger sample size and long-term effects is warranted.