Respiratory muscle training in neuromuscular disease: long-term effects on strength and load perception.


Author: Gozal D//Thiriet P

Affiliation: Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA. dgozal@tmcpop.tmc.tulane.edu
Conference/Journal: Med Sci Sports Exerc
Date published: 1999
Other:
 Volume ID: 31   ,  Issue ID: 11   ,  Pages: 1522-7   ,  Special Notes: Clinical Randomized controlled trial   ,  Word Count: 286  
    PURPOSE: Deterioration of respiratory muscle function in patients with neuromuscular disorders is primarily responsible for the high morbidity and mortality associated with these diseases. METHODS: The potential benefit of respiratory muscle training (RMT) on preservation of respiratory muscle strength and respiratory load perception (RLP) was examined in 21 children (mean age: 12.2 1.8 yr [SD], 16 male) with Duchenne's muscular dystrophy or
spinal muscular atrophy type III, and in 20 age-, weight-, and sex matched controls. Subjects were randomly allocated to undergo incremental RMT with resistive inspiratory and expiratory loads for a period of 6 months (trained group, TR) or to perform similar exercises with no load (NT). Maximal static inspiratory (Pi(max)) and expiratory (Pe(max)) pressures and RLP (modified Borg visual analog scale 0-10) were assessed on two separate occasions before beginning of the training protocol, monthly throughout RMT duration, and every 3-6 months upon cessation of RMT for 1 yr. 

RESULTS: In controls, no significant changes in maximal static pressures or load perception occurred during RMT or thereafter. Training in neuromuscular disorder (NMD) patients was associated with improvements in Pi(max) (mean delta max: .8 3.8 cmH2O in TR vs .2 3.6 cmH2O in NT; P < 0.02) and in Pe(max) (mean delta max:
.1 4.9 cmH2O in TR vs -1.8 3.4 cmH2O in NT; P < 0.004). Similarly, RLP significantly decreased during the RMT period in TR (mean delta: 1.9 0.3; P < 0.01) but did not change in NT (-0.2 0.2). In addition, with cessation of RMT, static pressures returned to pretraining values in TR within approximately 3 months. However, RLP was still improved after 12 months.

CONCLUSIONS: We conclude that in children with NMD, although RMT-induced increases in expiratory muscle strength are rapidly reversible, long-lasting improvements in RLP occur and could be associated with decreased respiratory symptoms.