Effects of Acute Salbutamol Intake on Peripheral and Central Fatigue in Trained Men

ABSTRACTPurposeErgogenic effect in physically active subjects has been reported following acute salbutamol (SAL) intake. β2-agonists have potential stimulant effects within the central nervous system that could be involved in this ergogenic effect. We hypothesized that acute SAL intake would induce changes in cerebral responses during exercise, with significant improvement in cerebral oxygenation and voluntary activation (VA) contributing to an increase in muscle performance.MethodsFourteen trained male subjects (25 ± 5 years) performed repeated isometric knee extensions until task failure (TF) following 4 mg (oral) SAL, 800 μg (inhaled) SAL, or placebo intake. VA, corticospinal excitability and inhibition assessed by transcranial magnetic stimulation (TMS) and changes in hemoglobin concentrations assessed by near infrared spectroscopy were measured before and during the fatiguing task.ResultsSAL had no significant effect both at rest and during exercise on prefrontal cortex oxygenation (e.g. changes in oxyhemoglobin concentration at TF: 4 mg SAL 11.4 ± 11.1 versus 800 μg SAL 10.4 ± 10.6 versus placebo 10.8 ± 8.1 μmol; P = 0.314) and neuromuscular function (e.g. VATMS at TF: 90.2 ± 6.6 versus 92.6 ± 5.0 versus 90.1 ± 7.0%; P = 0.760). SAL had no effect on the number of contractions until TF (95 ± 51 versus 100 ± 52 versus 93 ± 47; P = 0.629).ConclusionThese results indicate that acute SAL intake had no effect on central and peripheral mechanisms of neuromuscular fatigue and did not improve quadriceps endurance. Purpose Ergogenic effect in physically active subjects has been reported following acute salbutamol (SAL) intake. β2-agonists have potential stimulant effects within the central nervous system that could be involved in this ergogenic effect. We hypothesized that acute SAL intake would induce changes in cerebral responses during exercise, with significant improvement in cerebral oxygenation and voluntary activation (VA) contributing to an increase in muscle performance. Methods Fourteen trained male subjects (25 ± 5 years) performed repeated isometric knee extensions until task failure (TF) following 4 mg (oral) SAL, 800 μg (inhaled) SAL, or placebo intake. VA, corticospinal excitability and inhibition assessed by transcranial magnetic stimulation (TMS) and changes in hemoglobin concentrations assessed by near infrared spectroscopy were measured before and during the fatiguing task. Results SAL had no significant effect both at rest and during exercise on prefrontal cortex oxygenation (e.g. changes in oxyhemoglobin concentration at TF: 4 mg SAL 11.4 ± 11.1 versus 800 μg SAL 10.4 ± 10.6 versus placebo 10.8 ± 8.1 μmol; P = 0.314) and neuromuscular function (e.g. VATMS at TF: 90.2 ± 6.6 versus 92.6 ± 5.0 versus 90.1 ± 7.0%; P = 0.760). SAL had no effect on the number of contractions until TF (95 ± 51 versus 100 ± 52 versus 93 ± 47; P = 0.629). Conclusion These results indicate that acute SAL intake had no effect on central and peripheral mechanisms of neuromuscular fatigue and did not improve quadriceps endurance. Accepted for Publication: 19 January 2018 Corresponding author: Dr. Samuel Verges, Laboratoire HP2 (U1042 INSERM), Univ. Grenoble Alpes, UM Sports Pathologies, Hôpital Sud, Avenue Kimberley, 38 434 Echirolles - France. E-mail: sverges@chu-grenoble.fr This work has been funded by the French Anti-Doping Agency. The authors declare that they have no conflict of interest. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by the American College of Sports Medicine. © 2018 American College of Sports Medicine

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