Impact of salbutamol on muscle metabolism assessed by ³¹P NMR spectroscopy

Abstract

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 (4 mg) and a placebo. After treatment administration, subjects performed repetitive plantar flexions to exhaustion in a 3T magnet. Continuous (31) P 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 ± 7 W/23 ± 7 W; P = 0.001) and total work (1702 ± 442 J/1381 ± 432 J; 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.

Annual banned‐substance review: analytical approaches in human sports drug testing

“…These investigations generated a convincing body of evidence that the frequently observed increased lung functions of participants did not translate to improved endurance performance; however, the maximal voluntary isometric contraction of muscles was mentioned to be significantly elevated. Following the prohibited oral administration of 4 mg of salbutamol or inhalative application of 15 mg of terbutaline, the significant increase of maximal power and total work was reported, which supports the current WADA regulations concerning β 2 ‐agonists.…”

“…- [131,132,136,[138][139][140][141][142]144,[146][147][148][149] - [24,[125][126][127][128][129][130][132][133][134][135]137,143,145] S3 Beta-2-Agonists - [159][160][161][162][163] - [24,[150][151][152][153][154][155][156][157][158] S4 Hormone and metabolic modulators 1 Aromatase inhibitors [164] - [164] [ 24,165] 2 Selective estrogen receptor modulators (SERMs) - [167,169,170] - [24,…”

β2-Adrenergic agonist salbutamol augments hypertrophy in MHCIIa fibers and sprint mean power output but not muscle force during 11 weeks of resistance training in young men

“…The different results on peak power output with salbutamol in the current compared to other studies may be ascribed to differences in the intervention and dosing regimen. In some studies, subjects' last drug administration may have been close to the experimental visit, thus confounding measurements with acute beta 2 -agonist effects, which can increase measures of strength and power output when ingested in sufficiently high doses (6,8,15,16,18,25,26,29,48,54). Downloaded from journals.physiology.org/journal/jappl at Univ Southern Denmark-Syddansk Univ (130.225.157.199) on January 27, 2021.…”

Anabolic and lipolytic actions of beta2‐agonists in humans and antidoping challenges

“…Because the inhaled route is a more efficient way to achieve a high systemic bioavailability than with oral ingestion (by largely avoiding the first‐pass metabolism that occurs during absorption from the small intestine seen with oral dosing), the question of ergogenic effect is more influenced by the overall dose than the route. This is also the case when comparing some of the ergogenic effects on muscle strength and power observed in studies using oral administration of beta 2 ‐agonists with studies that utilized high dose inhalation . While muscle hypertrophy is scarcely explored for the inhaled route, daily inhalation of terbutaline at 4 mg (8 puffs from a 0.5 mg Turbohaler) for 4 weeks was recently shown to induce a 1 kg gain in lean mass in healthy young men .…”