title: Effect of salbutamol on neuromuscular function in endurance athletes.
abstract: OBJECTIVE
  The potential ergogenic effects of therapeutic inhaled salbutamol doses in endurance athletes have been controversially discussed for decades. We hypothesized that salbutamol inhalation may increase peripheral muscle contractility, reduce fatigability, and improve force recovery after a localized exercise in endurance athletes.
  
  
  METHODS
  Eleven healthy, nonasthmatic male athletes with high aerobic capacities were recruited to be compared in a double-blinded, randomized crossover study of two dose levels of salbutamol (200 and 800 μg) and a placebo administered by inhalation before a quadriceps fatigue test. Subjects performed an incremental exercise protocol consisting in sets of 10 intermittent isometric contractions starting at 20% of maximum voluntary contraction (MVC) with 10% MVC increment until exhaustion. Femoral nerve magnetic stimulation was used during and after MVC to evaluate neuromuscular fatigue after each set, at task failure, and after 10 and 30 min of recovery.
  
  
  RESULTS
  Initial MVC and evoked muscular responses were not modified with salbutamol (P > 0.05). The total number of submaximal contractions until task failure significantly differed between treatments (placebo, 72 ± 7; 200 µg, 78 ± 8; and 800 µg, 82 ± 7; P < 0.01). MVC and evoked muscular responses were similarly reduced with all treatments during the fatiguing task (all P > 0.05). Voluntary activation was unaffected by the fatiguing task and treatments (P > 0.05).
  
  
  CONCLUSIONS
  Supratherapeutic inhaled doses of β2-agonists increased quadriceps endurance during an incremental and localized fatiguing task in healthy endurance-trained athletes without significant effect on neuromuscular fatigue. Further studies are needed to clarify the underlying mechanisms.
authors.affiliation: 1HP2 Laboratory, Joseph Fourier University, Grenoble, FRANCE; 2INSERM U1042, Grenoble, FRANCE; 3Locomotion Unit, Reeducation and Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, CHU Grenoble, FRANCE; and 4Institute for Doping Prevention, Grenoble, FRANCE.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Decorte
authors.forename: Damien
authors.initials: D
authors.lastname: Bachasson
authors.forename: Michel
authors.initials: M
authors.lastname: Guinot
authors.forename: Patrice
authors.initials: P
authors.lastname: Flore
authors.forename: Patrick
authors.initials: P
authors.lastname: Levy
authors.forename: Samuel
authors.initials: S
authors.lastname: Verges
authors.forename: Bernard
authors.initials: B
authors.lastname: Wuyam
mesh_terms: D000280:Administration, Inhalation; D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000328:Adult; D000420:Albuterol / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004576:Electromyography; D005080:Exercise Test; D017079:Exercise Tolerance / Q000187:drug effects; D005267:Femoral Nerve / Q000187:drug effects* / Q000502:physiology; D005541:Forced Expiratory Volume; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects*; D053580:Muscle Strength / Q000187:drug effects*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D052097:Quadriceps Muscle / Q000294:innervation / Q000502:physiology*; D014797:Vital Capacity
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D000420:Albuterol