title: Noninvasive assessment of the tension-time index of inspiratory muscles at rest in obese male subjects.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of excessive mechanical load caused by obesity on the inspiratory muscle performance in obese men at rest.
  
  
  METHODS
  We therefore measure at rest spirometric flows and the noninvasive tension time index of inspiratory muscle (TTmus = PI/PImax x TI/TTOT) in eight obese male subjects (body mass index (BMI) > 30) and 10 controls.
  
  
  RESULTS
  Spirometric flow (FEV1% pred, FVC% pred) and maximal inspiratory pressure (PImax) were significantly lower in obese subjects compared to controls (P < 0.001). The mean TTmus was significantly higher in obese subjects than in controls (0.136 +/- 0.003 vs 0.045 +/- 0.01). The increase in TTmus was primarily due to an increase in the ratio of mean inspiratory pressure to maximal inspiratory pressure (PI/PImax) and the duty cycle (TI/TTOT). We found a significant negative relationship between PImax and BMI (r = -0.74, P < 0.001), a positive correlation between TTmus and BMI (r = 0.80, P < 0.001) and a negative correlation between TTmus and forced expiratory volume in 1 s (r = -0.85, P < 0.001).
  
  
  CONCLUSIONS
  Excessive mechanical load caused by obesity imposes a great burden on the inspiratory muscle, which may predispose such subjects to respiratory muscle weakness at rest.
authors.affiliation: EA 3300 APS and Motor Patterns: Adaptations-Rehabilitation, Sport Science Department, Picardie Jules Verne University, Amiens Cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Chlif
authors.forename: D
authors.initials: D
authors.lastname: Keochkerian
authors.forename: C
authors.initials: C
authors.lastname: Mourlhon
authors.forename: D
authors.initials: D
authors.lastname: Choquet
authors.forename: S
authors.initials: S
authors.lastname: Ahmaidi
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007320:Inspiratory Capacity; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology*; D012120:Respiration Disorders / Q000209:etiology / Q000503:physiopathology*; D012132:Respiratory Muscles / Q000503:physiopathology*; D013997:Time Factors; D014797:Vital Capacity