Hypertrophic effect of inhaled beta₂-agonist with and without concurrent exercise training: A randomized controlled trial

TY - JOUR

T1 - Hypertrophic effect of inhaled beta2-agonist with and without concurrent exercise training

T2 - A randomized controlled trial

AU - Jessen, Søren

AU - Onslev, Johan

AU - Lemminger, Anders Krogh

AU - Backer, Vibeke

AU - Bangsbo, Jens

AU - Hostrup, Morten

N1 - CURIS 2018 NEXS 193

PY - 2018/10

Y1 - 2018/10

N2 - Due to a high prevalence of asthma and exercise-induced bronchoconstriction in elite athletes, there is a high use of beta2-adrenoceptor agonists (beta2-agonists) in the athletic population. While anabolic in rodents, no study has been able to detect hypertrophy in humans after chronic beta2-agonist inhalation. We investigated whether inhaled beta2-agonist, terbutaline, alters body composition and metabolic rate with and without concurrent exercise training in healthy young men. Sixty-seven participants completed a 4-week intervention of daily terbutaline (8 × 0.5 mg) or placebo treatment without concurrent training (habitual; n = 23), with resistance (n = 23) or endurance (n = 21) training 3 times weekly. Before and after the interventions, participant's body composition was determined by dual-energy X-ray absorptiometry and resting metabolic rate and substrate oxidation by indirect calorimetry. Terbutaline increased lean body mass by 1.03 kg (95% CI 0.29-1.76; P <.05) and 1.04 kg (95% CI 0.16-1.93; P <.05) compared to placebo in the habitual and resistance training group, respectively, but had no effect compared to placebo in the endurance training group [−0.56 kg (95% CI −1.74-0.62; P >.05)]. Fat mass, bone mineral content, and resting metabolic rate did not change differently between treatments with the intervention. Daily inhalation of terbutaline in near-therapeutic doses induces skeletal muscle growth. This observation should be a concern for antidoping authorities.

AB - Due to a high prevalence of asthma and exercise-induced bronchoconstriction in elite athletes, there is a high use of beta2-adrenoceptor agonists (beta2-agonists) in the athletic population. While anabolic in rodents, no study has been able to detect hypertrophy in humans after chronic beta2-agonist inhalation. We investigated whether inhaled beta2-agonist, terbutaline, alters body composition and metabolic rate with and without concurrent exercise training in healthy young men. Sixty-seven participants completed a 4-week intervention of daily terbutaline (8 × 0.5 mg) or placebo treatment without concurrent training (habitual; n = 23), with resistance (n = 23) or endurance (n = 21) training 3 times weekly. Before and after the interventions, participant's body composition was determined by dual-energy X-ray absorptiometry and resting metabolic rate and substrate oxidation by indirect calorimetry. Terbutaline increased lean body mass by 1.03 kg (95% CI 0.29-1.76; P <.05) and 1.04 kg (95% CI 0.16-1.93; P <.05) compared to placebo in the habitual and resistance training group, respectively, but had no effect compared to placebo in the endurance training group [−0.56 kg (95% CI −1.74-0.62; P >.05)]. Fat mass, bone mineral content, and resting metabolic rate did not change differently between treatments with the intervention. Daily inhalation of terbutaline in near-therapeutic doses induces skeletal muscle growth. This observation should be a concern for antidoping authorities.

KW - Faculty of Science

KW - Physical activity

KW - Beta-agonist

KW - Adrenergic

KW - Athletes

KW - Doping

U2 - 10.1111/sms.13221

DO - 10.1111/sms.13221

M3 - Journal article

C2 - 29777633

SN - 0905-7188

VL - 28

SP - 2114

EP - 2122

JO - Scandinavian Journal of Medicine & Science in Sports

JF - Scandinavian Journal of Medicine & Science in Sports

IS - 10

ER -