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Decorte N.,Grenoble Alpes University | Decorte N.,French Institute of Health and Medical Research | Lamalle L.,Grenoble Alpes University | Lamalle L.,Grenoble University Hospital Center | And 13 more authors.
Scandinavian Journal of Medicine and Science in Sports | Year: 2015

The potential ergogenic effects of oral salbutamol intake were demonstrated for decades but the underlying mechanisms remain to elucidate. We hypothesized that improved exercise performance after acute oral salbutamol administration is associated with changes in muscle metabolism. Twelve healthy, nonasthmatic, moderately trained, male subjects were recruited to compare in a double-blind crossover randomized study, an oral dose of salbutamol (4mg) and a placebo. After treatment administration, subjects performed repetitive plantar flexions to exhaustion in a 3T magnet. Continuous 31P nuclear magnetic resonance spectroscopy assessment of the calf muscles was performed at rest, during exercise, and during recovery. No significant difference between treatments was detected in metabolite concentration at rest (P>0.05). Creatine phosphate and inorganic phosphate changes during and immediately after exercise were similar between treatments (P>0.05). Intramuscular pH (pHi) was significantly higher at rest, at submaximal exercise but not at exhaustion with salbutamol (pHi at 50% of exercise duration, 6.8±0.1/6.9±0.1 for placebo and salbutamol, respectively, P<0.05). The maximal power (28±7W/23±7W; P=0.001) and total work (1702±442J/1381±432J; P=0.003) performed during plantar flexions were significantly increased with salbutamol. Salbutamol induced significant improvement in calf muscle endurance with similar metabolic responses during exercise, except slight differences in pHi. Other mechanisms than changes in muscle metabolism may be responsible for the ergogenic effect of salbutamol administration. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Decorte N.,Joseph Fourier University | Decorte N.,French Institute of Health and Medical Research | Decorte N.,Grenoble University Hospital Center | Bachasson D.,Joseph Fourier University | And 18 more authors.
Medicine and Science in Sports and Exercise | Year: 2013

PURPOSE: 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). CONCLUSION: 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. Copyright © 2013 by the American College of Sports Medicine.

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