Abstract
Chronic beta2-adrenoceptor activation with beta2-agonists has been shown to induce muscle hypertrophy and modify contractile characteristics of skeletal muscles in rodents. In humans, these effects are unexplored. The purpose of the present study was to investigate the effect of four weeks of beta2-adrenoceptor activation with oral terbutaline on lean body mass and quadriceps contractile properties in active men. Eighteen men were randomly assigned in two groups (terbutaline, n=9 (TER) or placebo, n=9 (PLA)). Before and after four weeks of oral administration of 5 mg/30 kgbw terbutaline twice daily or placebo, subjects' body composition were determined by dual X-ray absorbance. Furthermore, subjects' VO2max and quadriceps contractile properties were measured before and after the intervention. After the intervention, lean body mass was 1.7±0.7 kg higher (P < 0.05) in TER compared with before. Furthermore, fat mass reduced by 1.4±0.6 kg (P < 0.05) with the intervention in TER. Quadriceps muscle strength and peak twitch force were 13.3±4.2 and 31.0±4.9% higher (P < 0.01) after the intervention in TER compared with before. No differences were observed in voluntary activation for group and time. No differences were observed in PLA with the intervention. In conclusion, four weeks of beta2-adrenoceptor activation with oral terbutaline induces muscle hypertrophy and enhances skeletal muscle contractile properties of active men. Future studies should evaluate whether treatment with systemic beta2-agonist can help attenuate muscle wasting associated with disease.
- © 2014 ERS