title: The relationship among inspiratory muscle strength, the perception of dyspnea and inhaled beta2-agonist use in patients with asthma.
abstract: BACKGROUND
  It is well documented that the perception of dyspnea (POD), subjectively reported by patients, is related to the activity and strength of the inspiratory muscles, and influences the use of 'as needed' beta2-agonists.
  
  
  OBJECTIVE
  To investigate the relationship among the increase in inspiratory muscle strength after specific inspiratory muscle training, beta2-agonist consumption and the POD in patients with persistent, mild to moderate asthma.
  
  
  METHODS
  Inspiratory muscle strength, daily beta2-agonist consumption and the POD were measured in 30 patients with mild to moderate asthma. Patients were then randomly assigned to two groups: one group received specific inspiratory muscle training until an increase of more than 20 cm H2O was reached, and one group was a control group and received sham training. Inspiratory muscle strength, the POD and daily beta2-agonist consumption were assessed during and after the training period.
  
  
  RESULTS
  There was no good correlation between the baseline maximal inspiratory pressure and the POD, or between the baseline maximal inspiratory pressure and the mean daily beta2-agonist consumption. However, there was a significant correlation between the POD and the mean daily beta2-agonist consumption. The increase in inspiratory muscle strength after the inspiratory muscle training was closely correlated with the decrease in the POD (P<0.001) and the decrease in beta2-agonist consumption (P<0.001).
  
  
  CONCLUSIONS
  The present study shows that, in patients with mild to moderate, persistent asthma, there is a correlation between the POD and the mean daily beta2-agonist consumption. When the inspiratory muscles are strengthened, there is a significant decrease in the POD and in beta2-agonist consumption.
authors.affiliation: Department of Medicine A, Hillel Yaffe Medical Center, Hadera, Israel. weiner@hillel-yaffe.health.gov.il
authors.forename: Paltiel
authors.initials: P
authors.lastname: Weiner
authors.forename: Rasmi
authors.initials: R
authors.lastname: Magadle
authors.forename: Marinella
authors.initials: M
authors.lastname: Beckerman
authors.forename: Noa
authors.initials: N
authors.lastname: Berar-Yanay
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000328:Adult; D001249:Asthma / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D001945:Breathing Exercises; D004417:Dyspnea / Q000209:etiology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D012132:Respiratory Muscles / Q000503:physiopathology*; D014797:Vital Capacity
chemical_list: D000318:Adrenergic beta-Agonists