Effects of short-term oral salbutamol administration on exercise endurance and metabolism

Summer Olympic sports and female athletes: comparison of anti-doping collections and prohibited substances detected in Australia and New Zealand vs. France

Like any athlete, female athletes may be tempted to use prohibited substances during competition or training to enhance their performance. Anti-doping tests performed on female athletes in summer Olympic sports from two geographical areas: Australia/ New Zealand, and France were compared. First, the distribution of sample collections across different sports disciplines, as well as the distribution of substances was investigated. Then the distribution of collections and substances detected in the five sports categories (Strength/Speed, Endurance, Mixed, Motor Skills with High Energy Expenditure, and Motor Skills with Low Energy Expenditure) were studied with consideration of therapeutic use exemptions obtained by the athlete. Australia/New Zealand and France were similar in their overall number of anti-doping collections performed. Likewise, both regions had the same sports disciplines (athletics, aquatics, cycling) and sport categories (Mixed and Endurance) as having the highest number of sample collections. The Motor Skills with High Energy Expenditure, and Motor Skills with Low Energy Expenditure categories had the lowest number of sample collections. However, the number of substances detected was significantly different (p < 0.05) with a greater number of substances found in the French data. There were a few substances in common between the two geographical areas, namely prednisone/prednisolone, carboxy-THC, terbutaline, vilanterol and methylphenidate, but most were different. In-competition tests were the category where most of the AAFs were found.

Salbutamol Attenuates Diabetic Skeletal Muscle Atrophy by Reducing Oxidative Stress, Myostatin/GDF-8, and Pro-Inflammatory Cytokines in Rats

Type 2 diabetes is a metabolic disorder that leads to accelerated skeletal muscle atrophy. In this study, we aimed to evaluate the effect of salbutamol (SLB) on skeletal muscle atrophy in high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic rats. Male Sprague Dawley rats were divided into four groups (n = 6): control, SLB, HFD/STZ, and HFD/STZ + SLB (6 mg/kg orally for four weeks). After the last dose of SLB, rats were assessed for muscle grip strength and muscle coordination (wire-hanging, rotarod, footprint, and actophotometer tests). Body composition was analyzed in live rats. After that, animals were sacrificed, and serum and gastrocnemius (GN) muscles were collected. Endpoints include myofibrillar protein content, muscle oxidative stress and antioxidants, serum pro-inflammatory cytokines (interleukin-1β, interleukin-2, and interleukin-6), serum muscle markers (myostatin, creatine kinase, and testosterone), histopathology, and muscle 1H NMR metabolomics. Findings showed that SLB treatment significantly improved muscle strength and muscle coordination, as well as increased lean muscle mass in diabetic rats. Increased pro-inflammatory cytokines and muscle markers (myostatin, creatine kinase) indicate muscle deterioration in diabetic rats, while SLB intervention restored the same. Also, Feret's diameter and cross-sectional area of GN muscle were increased by SLB treatment, indicating the amelioration in diabetic rat muscle. Results of muscle metabolomics exhibit that SLB treatment resulted in the restoration of perturbed metabolites, including histidine-to-tyrosine, phenylalanine-to-tyrosine, and glutamate-to-glutamine ratios and succinate, sarcosine, and 3-hydroxybutyrate (3HB) in diabetic rats. These metabolites showed a pertinent role in muscle inflammation and oxidative stress in diabetic rats. In conclusion, findings showed that salbutamol could be explored as an intervention in diabetic-associated skeletal muscle atrophy.

Detection of Asthma Inhaler Use via Terahertz Spectroscopy

Inhaled medications are commonplace for administering bronchodilators, anticholinergics, and corticosteroids. While they have a defined legitimate use, they are also used in sporting events as performance-enhancing drugs. These performance enhancers can be acquired via both legal (i.e., at a pharmacy through over-the-counter medications or through a prescription) and illicit (i.e., black market and foreign pharmacies) means, thus making monitoring procurement impossible. While urine tests can detect these pharmacological agents hours after they have been inhaled, there is a significant lag time before they are observed in urine. Direct detection of these inhaled agents is complicated and requires a multiplexed approach due to the sheer number of inhaled pharmacological agents. Therefore, detection of propellants, which carry the drug into the lungs, provides a simpler path forward toward detection of broad pharmacological agents. In this paper, we demonstrate the first use of terahertz spectroscopy (THz) to detect inhaled medications in human subjects. Notably, we were able to detect and quantitate the propellant, HFA-134a, in breath up to 30 min after using an asthma inhaler, enabling the use of a point-of-care device to monitor exhaled breath for the presence of propellants. We also demonstrate via simulations that the same approach can be leveraged to detect and identify next-generation propellants, specifically HFA-152a. As a result, we provide evidence that a single point-of-care THz sensor can detect when individuals have used pressure-mediated dose inhalers (pMDIs) without further modification of the hardware.

Combinatory in vitro effects of the β2-agonists salbutamol and formoterol in skeletal muscle cells

β2-agonists are used for the treatment of bronchoconstriction, but also abused in doping. Beside an ergogenic activity β2-agonists may have also anabolic activity. Therefore, we investigated the anabolic activity and associated molecular mechanisms of Salbutamol (SAL) and Formoterol (FOR) alone, as well as in combination in C2C12 myotubes. In differentiated C2C12 cells, dose-dependent effects of SAL and FOR (alone/in combination) on myotube diameter, myosin heavy chain (MHC) protein expression and the mRNA expression of genes involved in hypertrophy were analyzed. β2-adrenoceptor 2 (ADRB2), androgen receptor (AR) and estrogen receptor (ER) inhibitors, as well as dexamethasone (Dexa) were co-incubated with the β2-agonists and myotube diameter was determined. SAL and FOR treatment significantly induced hypertrophy and increased MHC expression and the mRNA expression of Igf1, mTOR, PIk3r1 and AMpKa2. In contrast to an ER inhibitor, the ADRB2 and AR inhibitors, as well as Dexa antagonized FOR and SAL induced hypertrophy. Combined treatment with SAL and FOR resulted in significant additive effects on myotube diameter and MHC expression. Future clinical studies are needed to prove this effect in humans and to evaluate this finding with respect to antidoping regulations.

Prevalence of Prohibited Substance Use and Methods by Female Athletes: Evidence of Gender-Related Differences

To achieve optimal sports performances, women and men may show specific doping practices because of the physiological and psychological gender differences, but there are few data on this topic. Here, we report the apparent use of prohibited substances and methods by female athletes based on analyses of the doping tests collected by the French Anti-Doping Agency from 2013 to 2019. We compared the frequency of use and the ergogenic and side effects to those of their male counterparts. The results revealed lower use of prohibited substances in female vs. male athletes, with significantly fewer anabolic agents, hormone and metabolic modulators, and cannabinoids. Gender specificity in utilization of substance classes was also shown. Relatively lower use of hormone modulators and cannabinoids and higher use of beta-2 agonists, diuretics and glucocorticoids were found in the woman cohort compared with men cohort, combined with the different choice of substances, possibly because of the altered ergogenic and/or side effects. However, no impact due to gender regarding the sports disciplines was observed, with both women and men showing similar use of anabolic agents, mainly in the anaerobic sports, and EPO and corticoids, mainly in endurance or mixed sports. Further studies are needed to put these French data into a global perspective, comparing uses across countries and exploring possible new developments in the fight against doping in women.

Inhaling salbutamol may decrease time to exhaustion in some contexts of heavy endurance performances

PURPOSE

To study the effect of inhaling a beta-agonist (salbutamol) compared to placebo on skiing and cycling performance in well-trained elite athletes.

METHODS

Three different exercise protocols were used, all with a cross-over double blind placebo-controlled design. Participants inhaled 800 µg salbutamol or a placebo prior to the test, which was repeated on a following day with the participants inhaling the other substance. Fifteen junior elite skiers performed four free-style high intensity sprints (1100 m/work time 3.5 - 4.5 min). Twelve elite cyclists carried out a short cycling protocol, starting with two 5 min submaximal workloads followed by a maximal intermittent performance test to exhaustion. Another 12 elite cyclists performed the maximal intermittent performance test to exhaustion after a 150 min long submaximal cycling protocol.

RESULTS

Group mean time for the ski sprints increased, with no difference between treatment groups. In the short cycling protocol time to exhaustion was 9.1% (95% CI 52 to 161) lower after inhaling salbutamol compared to placebo and in the long cycling protocol time to exhaustion was 9.1% (95% CI -121 to 267) lower after inhaling salbutamol compared to placebo. Blood lactate, heart rate and ventilation increased during submaximal exercise with salbutamol compared to placebo in the short cycling protocol (p < 0.05).

CONCLUSION

This study could not confirm any positive performance effects from inhaling 800 µg salbutamol compared to placebo in skiing and cycling high-intensity intermittent performance. Instead, time to exhaustion in the maximal intermittent performance test was lower in both cycling protocols.

Aerobic performance among healthy (non-asthmatic) adults using beta2-agonists: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To examine the effect of beta2-agonists on aerobic performance in healthy, non-asthmatic study participants.

DESIGN

Systematic review and meta-analysis.

ELIGIBILITY CRITERIA

We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials published until December 2019. Studies examining the effect of beta2-agonists on maximal physical performance lasting longer than 1 min were included in the meta-analysis. Data are presented as standardised difference in mean (SDM) with 95% CI.

RESULTS

The present meta-analysis includes 47 studies. The studies comprise 607 participants in cross-over trials, including 99 participants in three-way cross-over trials and 27 participants in a four-way cross-over trial. Seventy-three participants were included in parallel trials. Beta2-agonists did not affect aerobic performance compared with placebo (SDM 0.051, 95% CI -0.020 to 0.122). The SDM for the included studies was not heterogeneous (I²=0%, p=0.893), and the effect was not related to type of beta2-agonist, dose, administration route, duration of treatment or performance level of participants. Beta2-agonists had no effect on time trial performance, time to exhaustion or maximal oxygen consumption (p<0.218).

CONCLUSION/IMPLICATION

The present study shows that beta2-agonists do not affect aerobic performance in non-asthmatic subjects regardless of type, dose, administration route, duration of treatment or performance level of participants. The results of the present study should be of interest to WADA and to anyone who is interested in equal opportunities in competitive sports.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018109223.

Exercise performance after salbutamol inhalation in non-asthmatic, non-athlete individuals: a randomised, controlled, cross-over trial

Background

Asthma is a frequent diagnosis in competitive sports, and inhaled β₂-agonists are commonly used by athletes. Although inhaled β₂-agonists do not seem to improve performance in athletes, it has remained uncertain whether they can increase exercise performance in non-athletes.

Objective

To investigate the effect of inhaled β₂-agonists on exercise performance in healthy non-athlete individuals.

Methods

In a double-blinded, placebo-controlled, cross-over trial, healthy, non-asthmatic, non-athlete individuals were randomised to inhalation of either 900 µg of salbutamol or placebo. Cardiopulmonary exercise testing, dynamic spirometry and impulse oscillometry were performed. The primary outcome was the effect from salbutamol on peak oxygen uptake, whereas secondary outcomes were breathing reserve and ventilation efficiency, and workload, heart rate, breath rate and minute ventilation at peak exercise under influence of salbutamol.

Results

A total of 36 healthy subjects with a mean age of 26±5 years were included. Salbutamol had no effect on peak oxygen uptake compared with placebo, 46.8±1.3 mL/kg/min versus 46.6±1.2 mL/kg/min, p=0.64. Salbutamol had no effect on workload, p=0.20, heart rate, p=0.23, breath rate, p=0.10, or minute ventilation, p=0.26, at peak exercise compared with placebo. Salbutamol lowered oxygen uptake, p=0.04, and workload, p=0.04, at anaerobic threshold compared with placebo. Forced expiratory volume in 1 s, 116%±13% of predicted, and peak expiratory flow, 122%±16% of predicted, increased after inhalation of salbutamol compared with placebo; 109%±13% and 117%±17%, respectively, p<0.01. Breathing reserve was found to be higher, 22%±2%, after salbutamol inhalation than after placebo, 16%±2%, p<0.01.

Conclusion

Inhaled salbutamol did not improve peak oxygen uptake in healthy, non-asthmatic, non-athlete individuals compared with placebo.

Trial registration number

NCT02914652.

Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic β2-adrenergic stimulation in men

The study was a randomized placebo-controlled trial investigating mechanisms by which chronic β2-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group [oral terbutaline 5 mg/30 kg body weight (bw) twice daily (TER); n = 9] or a control group [placebo (PLA); n = 9] for a 4-wk intervention. No changes were observed with the intervention in PLA. Isometric muscle force of the quadriceps increased ( P ≤ 0.01) by 97 ± 29 N (means ± SE) with the intervention in TER compared with PLA. Peak and mean power output during 30 s of maximal cycling increased ( P ≤ 0.01) by 32 ± 8 and 25 ± 9 W, respectively, with the intervention in TER compared with PLA. Maximal oxygen consumption (V̇o2max) and time to fatigue during incremental cycling did not change with the intervention. Lean body mass increased by 1.95 ± 0.8 kg ( P ≤ 0.05) with the intervention in TER compared with PLA. Change in single fiber cross-sectional area of myosin heavy chain (MHC) I (1,205 ± 558 μm2; P ≤ 0.01) and MHC II fibers (1,277 ± 595 μm2; P ≤ 0.05) of the vastus lateralis muscle was higher for TER than PLA with the intervention, whereas no changes were observed in MHC isoform distribution. Expression of muscle proteins involved in growth, ion handling, lactate production, and clearance increased ( P ≤ 0.05) with the intervention in TER compared with PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force and peak power during maximal cycling induced by chronic β2-adrenergic stimulation in humans.

Formoterol concentrations in blood and urine: the World Anti-Doping Agency 2012 regulations

INTRODUCTION

We examined urinary and serum concentrations of formoterol in asthmatic and healthy individuals after a single dose of 18 μg inhaled formoterol and after repeated inhaled doses in healthy individuals. Results were evaluated using the World Anti-Doping Agency (WADA) 2012 threshold for formoterol.

METHODS

On the day of this open-label, crossover study, 10 asthmatic subjects who regularly used beta2-agonists and 10 healthy participants with no previous use of beta2-agonists received a single dose of 18 μg formoterol. Further, 10 nonasthmatic participants inhaled 18 μg formoterol every second hour until obtaining a total of 72 μg, which is twice the maximum daily dose (36 μg formoterol) permitted by the WADA. Blood samples were collected at baseline, 30 min, 1, 2, 3, 4, and 6 h after the first inhalation. Urine samples were collected at baseline, 0-4, 4-8, and 8-12 h after the first inhalation.

RESULTS

Median urine concentration, corrected for specific gravity, after the single-dose administration peaked during 0-4 h after inhalation at a maximum of 7.4 ng·mL(-1) in asthmatic subjects and 7.9 ng·mL(-1) in healthy subjects. Median urine concentration after repeated doses peaked during 4-8 h after inhalation of a total of 72 μg formoterol at a maximum of 16.8 ng·mL(-1) in healthy participants. The maximum individual concentration of 25.6 ng·mL(-1) was found after inhalation of a total of 72 μg formoterol.

CONCLUSIONS

We found no significant differences in urinary and serum concentrations of formoterol between asthmatic and healthy subjects. We found high interindividual variability in the concentrations in all groups. Our data support the WADA 2012 urinary threshold of 30 ng·mL(-1) formoterol as being an adverse analytical finding.

In vitro effects of Beta-2 agonists on skeletal muscle differentiation, hypertrophy, and atrophy

Background

Beta-2 agonists are widely used in the treatment of asthma and chronic obstructive pulmonary disease for their effect on airway smooth muscle relaxation. They also act on skeletal muscle, although their reported ergogenic effect is controversial.

Aim

To evaluate the in vitro effects of short-acting and long-acting beta-2 agonists on adrenergic receptor (ADR) expression, hypertrophy, and atrophy markers, in a skeletal muscle cell line.

Methods

The C2C12 cell line was used as a model of skeletal muscle differentiation. ADR messenger RNA expression was evaluated in proliferating myoblasts, committed cells, and differentiated myotubes, in basal conditions and after treatment with 10^-6 M clenbuterol, salbutamol, salmeterol, and formoterol. Effect of beta-2 agonists on gene and protein expression of hypertrophy and atrophy markers was assessed in differentiated myotubes.

Results

Our study shows that beta-2 ADR messenger RNA was expressed and progressively increased during cell differentiation. Beta-2 agonist treatment did not affect its expression. Skeletal muscle hypertrophy markers (fast and slow myosin, myogenin) were not modulated by any of the beta-2 agonists evaluated. However, clenbuterol induced a significant, dose-dependent downregulation of skeletal muscle atrophy genes (atrogin-1, MuRF-1, and cathepsin L).

Conclusions

The reported ergogenic effect of beta-2 agonists, if any, should be considered as drug-specific and not class-specific and that of clenbuterol is mediated by the inhibition of the atrophic pathway.

Acute supra-therapeutic oral terbutaline administration has no ergogenic effect in non-asthmatic athletes

This study aimed to investigate the effects on a possible improvement in aerobic and anaerobic performance of oral terbutaline (TER) at a supra-therapeutic dose in 7 healthy competitive male athletes. On day 1, ventilatory threshold, maximum oxygen uptake [Formula: see text] and corresponding power output were measured and used to determine the exercise load on days 2 and 3. On days 2 and 3, 8 mg of TER or placebo were orally administered in a double-blind process to athletes who rested for 3 h, and then performed a battery of tests including a force-velocity exercise test, running sprint and a maximal endurance cycling test at Δ50 % (50 % between VT and [Formula: see text]). Lactatemia, anaerobic parameters and endurance performance ([Formula: see text] and time until exhaustion) were raised during the corresponding tests. We found that TER administration did not improve any of the parameters of aerobic performance (p > 0.05). In addition, no change in [Formula: see text] kinetic parameters was found with TER compared to placebo (p > 0.05). Moreover, no enhancement of the force-velocity relationship was observed during sprint exercises after TER intake (p > 0.05) and, on the contrary, maximal strength decreased significantly after TER intake (p < 0.05) but maximal power remained unchanged (p > 0.05). In conclusion, oral acute administration of TER at a supra-therapeutic dose seems to be without any relevant ergogenic effect on anaerobic and aerobic performances in healthy athletes. However, all participants experienced adverse side effects such as tremors.

Pharmacology and therapeutics of bronchodilators

Bronchodilators are central in the treatment of of airways disorders. They are the mainstay of the current management of chronic obstructive pulmonary disease (COPD) and are critical in the symptomatic management of asthma, although controversies around the use of these drugs remain. Bronchodilators work through their direct relaxation effect on airway smooth muscle cells. at present, three major classes of bronchodilators, β(2)-adrenoceptor (AR) agonists, muscarinic receptor antagonists, and xanthines are available and can be used individually or in combination. The use of the inhaled route is currently preferred to minimize systemic effects. Fast- and short-acting agents are best used for rescue of symptoms, whereas long-acting agents are best used for maintenance therapy. It has proven difficult to discover novel classes of bronchodilator drugs, although potential new targets are emerging. Consequently, the logical approach has been to improve the existing bronchodilators, although several novel broncholytic classes are under development. An important step in simplifying asthma and COPD management and improving adherence with prescribed therapy is to reduce the dose frequency to the minimum necessary to maintain disease control. Therefore, the incorporation of once-daily dose administration is an important strategy to improve adherence. Several once-daily β(2)-AR agonists or ultra-long-acting β(2)-AR-agonists (LABAs), such as indacaterol, olodaterol, and vilanterol, are already in the market or under development for the treatment of COPD and asthma, but current recommendations suggest the use of LABAs only in combination with an inhaled corticosteroid. In addition, some new potentially long-acting antimuscarinic agents, such as glycopyrronium bromide (NVA-237), aclidinium bromide, and umeclidinium bromide (GSK573719), are under development, as well as combinations of several classes of long-acting bronchodilator drugs, in an attempt to simplify treatment regimens as much as possible. This review will describe the pharmacology and therapeutics of old, new, and emerging classes of bronchodilator.

β₂-Agonists and physical performance: a systematic review and meta-analysis of randomized controlled trials

Inhaled β₂-agonists are commonly used as bronchodilators in the treatment of asthma. Their use in athletes, however, is restricted by anti-doping regulations. Controversies remain as to whether healthy elite athletes who use bronchodilators may gain a competitive advantage. The aim of this systematic review and meta-analysis is to assess the effects of inhaled and systemic β₂-agonists on physical performance in healthy, non-asthmatic subjects. To this end, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to August 2009. Reference lists were searched for additional relevant studies. The search criteria were for randomized controlled trials examining the effect of inhaled or systemic β₂-agonists on physical performance in healthy, non-asthmatic subjects. Two authors independently performed the selection of studies, data extraction and risk of bias assessment. Parallel-group and crossover trials were analysed separately. Mean difference (MD) and 95% confidence intervals were calculated for continuous data and, where possible, data were pooled using a fixed effects model. Twenty-six studies involving 403 participants (age range 7-30 years) compared inhaled β₂-agonists with placebo. No significant effect could be detected for inhaled β₂-agonists on maximal oxygen consumption (VO₂(max)) [MD -0.14 mL · kg⁻¹ · min⁻¹; 95% CI -1.07, 0.78; 16 studies], endurance time to exhaustion at 105-110% VO₂(max) (MD -1.5 s; 95% CI -15.6, 12.6; four studies), 20-km time trial duration (MD -4.4 s; 95% CI -23.5, 14.7; two studies), peak power (MD -0.14 W · kg⁻¹; 95% CI -0.54, 0.27; four studies) and total work during a 30-second Wingate test (MD 0.80 J · kg⁻¹; 95% CI -2.44, 4.05; five studies). Thirteen studies involving 172 participants (age range 7-22 years) compared systemic β₂-agonists with placebo, with 12 studies involving oral and one study involving intravenous salbutamol. A significant effect was detected for systemic β₂-agonists on endurance time to exhaustion at 80-85% VO₂(max) (MD 402 s; 95% CI 34, 770; two studies), but not for VO₂(max) (placebo 42.5 ± 1.7 mL · kg⁻¹ · min⁻¹, salbutamol 42.1 ± 2.9 mL · kg⁻¹ · min⁻¹, one study), endurance time to exhaustion at 70% VO₂(max) (MD 400 s; 95% CI -408, 1208; one study) or power output at 90% VO₂(max) (placebo 234.9 ± 16 W, salbutamol 235.5 ± 18.1 W, one study). A significant effect was shown for systemic β₂-agonists on peak power (MD 0.91 W · kg⁻¹; 95% CI 0.25, 1.57; four studies), but not on total work (MD 7.8 J · kg⁻¹; 95% CI -3.3, 18.9; four studies) during a 30-second Wingate test. There were no randomized controlled trials assessing the effects of systemic formoterol, salmeterol or terbutaline on physical performance. In conclusion, no significant effects were detected for inhaled β₂-agonists on endurance, strength or sprint performance in healthy athletes. There is some evidence indicating that systemic β₂-agonists may have a positive effect on physical performance in healthy subjects, but the evidence base is weak.

High-dose inhaled salbutamol has no acute effects on aerobic capacity or oxygen uptake kinetics in healthy trained men

The prevalence of asthma is higher among elite athletes than in the general population. This has resulted in the frequent use of anti-asthmatic medication such as beta2-agonists among asthmatic athletes. Beta2-agonists are on the prohibited list of WADA. The use of the beta2-agonist salbutamol is only permitted in therapeutic inhaled doses. Most studies have reported the lack of ergogenic effects of therapeutic doses of inhaled beta2-agonists measured in maximal oxygen uptake. No previous studies have examined any possible effects of high-dose inhaled salbutamol on oxygen uptake kinetics. We enrolled nine healthy well-trained men in a randomized, blinded, placebo-controlled crossover study. Subjects were randomized to inhalation of 40 puffs of 0.2 mg salbutamol or two placebo tablets and performed an incremental test to exhaustion and three submaximal tests at 75% of peak power to determine oxygen uptake kinetics. During the incremental test, there were no effects of inhaled salbutamol on VO(2max) in absolute or relative terms, and no effect on peak power and lactate threshold. During the submaximal test, we found no effects on the time constant, time delay, the mean response time or O(2) deficit related to oxygen uptake kinetics. In conclusion, no ergogenic effect of a high dose of salbutamol on aerobic capacity was found.

Use of prescription drugs in athletes

Although athletes are young and generally healthy, they use a variety of non-doping classified medicines to treat injuries, cure illnesses and obtain a competitive edge. Athletes and sports medicine physicians try to optimize the treatment of symptoms related to extreme training during an elite athlete's active career. According to several studies, the use of antiasthmatic medication is more frequent among elite athletes than in the general population. The type of training and the kind of sport influence the prevalence of asthma. Asthma is most common among those competing in endurance events, such as cycling, swimming, cross-country skiing and long-distance running. Recent studies show that athletes use also NSAIDs and oral antibacterials more commonly than age-matched controls, especially athletes competing in speed and power sports. Inappropriately high doses and concomitant use of several different NSAIDs has been observed. All medicines have adverse effects that may have deleterious effects on elite athletes' performance. Thus, any unnecessary medication use should be minimized in elite athletes. Inhaled beta(2)-agonists may cause tachycardia and muscle tremor, which are especially harmful in events requiring accuracy and a steady hand. In experimental animal models of acute injury, especially selective cyclo-oxygenase-2 inhibitors have been shown to be detrimental to tissue-level repair. They have been shown to impair mechanical strength return following acute injury to bone, ligament and tendon. This may have clinical implications for future injury susceptibility. However, it should be noted that the current animal studies have limited translation to the clinical setting. Adverse effects related to the CNS and gastrointestinal adverse reactions are commonly reported in connection with NSAID use also in elite athletes. In addition to the potential for adverse effects, recent studies have shown that NSAID use may negatively regulate muscle growth by inhibiting protein synthesis. Physicians and pharmacists taking care of athletes' medication need to be aware of the medicines that an athlete is taking and how those medicines interact with performance, exercise, environment and other medicines. Sport associations should repeatedly monitor not only the use of banned substances, but also the trends of use of legal medicines in athletes. Not only physicians and pharmacists, but also athletes and coaches should be better educated with respect to potential benefits and risks, and how each agent may affect an athlete's performance. The attitudes and beliefs leading to ample use of legal medicines in athletes is an interesting area of future research.

Salbutamol intake and substrate oxidation during submaximal exercise

In order to test the hypothesis that salbutamol would change substrate oxidation during submaximal exercise, eight recreationally trained men twice performed 1 h at 60% VO(2) peak after ingestion of placebo or 4 mg of salbutamol. Gas exchange was monitored and blood samples were collected during exercise for GH, ACTH, insulin, and blood glucose and lactate determination. With salbutamol versus placebo, there was no significant difference in total energy expenditure and substrate oxidation, but the substrate oxidation balance was significantly modified after 40 min of exercise. ACTH was significantly decreased with salbutamol during the last 10 min of exercise, whereas no difference was found between the two treatments in the other hormonal and metabolic parameters. The theory that the ergogenic effect of salbutamol results from a change in substrate oxidation has little support during relatively short term endurance exercise, but it is conceivable that longer exercise duration can generate positive findings.

Pharmaceutical treatment of asthma symptoms in elite athletes - doping or therapy?

Asthma, exercise-induced bronchoconstriction, and airway hyper-responsiveness are often found in elite athletes, perhaps as a consequence of their sport or maybe because asthma is a common disorder in young adults. Inhaled beta2-agonists (IBA) are frequently used in elite athletes, but due to regulations introduced by the International Olympic Committee, the use of anti-asthmatic therapy might change. Drugs that make ergogenic effect persist are prohibited in all athletes, whether or not they take part in competitions and systemic steroids and beta2-agonists are among such drugs. On the other hand, opinion is more divided about the use of inhaled corticosteroids (ICS) and IBA. In humans, no effect has been found on the oxygen uptake, performance or distance run with therapeutic doses of IBA, either in asthmatics or non-asthmatics, whereas others report an ergogenic effect and better lung function of high doses of a beta2-agonist in non-asthmatics. Anti-asthmatic treatment is necessary for asthmatics, but should not be used by non-asthmatic elite athletes due to both possible systemic effects and furthermore, side effects of both ICS and IBA.

[Salbutamol improves diaphragm force generation in experimental sepsis]

OBJECTIVE

In a high percentage of cases, severe sepsis is accompanied by acute respiratory failure, in which weakness of the respiratory muscles plays an important role. Weakened respiratory muscles that are subjected to an increased mechanical load may develop muscle fatigue, with exacerbation of the respiratory failure. Because beta2-adrenergic drugs increase muscle contraction force, they may play a role in preventing and managing respiratory failure in septic patients. Our aim was to study the effects of salbutamol on diaphragm function in an animal model of peritoneal sepsis.

MATERIAL AND METHODS

The study included 3 groups of animals: a) a control group (n=7), in which the animals underwent a median laparotomy without visceral manipulation; b) a septic group (n=10), in which peritoneal sepsis was induced by cecal ligation and puncture (CLP); and c) a salbutamol group (n=7), in which peritoneal sepsis (CLP) was treated with salbutamol. Hemodynamic parameters and blood gases were measured in vivo. Diaphragm function was evaluated in vitro.

RESULTS

Salbutamol increased aortic blood flow and heart rate while it reduced mean arterial pressure in the animals with peritoneal sepsis (P< .05). Sepsis produced a significant drop in diaphragmatic force both before and after the application of a muscle-fatigue protocol. Treatment with salbutamol improved muscle contraction force before and after application of the protocol (P< .05).

CONCLUSIONS

The use of beta2-adrenergic drugs such as salbutamol improves diaphragm function in experimental sepsis. The mechanisms that produce this improvement require further study.

Do inhaled beta(2)-agonists have an ergogenic potential in non-asthmatic competitive athletes?

The prevalence of asthma is higher in elite athletes than in the general population. The risk of developing asthmatic symptoms is the highest in endurance athletes and swimmers. Asthma seems particularly widespread in winter-sport athletes such as cross-country skiers. Asthmatic athletes commonly use inhaled beta(2)-agonists to prevent and treat asthmatic symptoms. However, beta(2)-agonists are prohibited according to the Prohibited List of the World Anti-Doping Agency. An exception can be made only for the substances formoterol, salbutamol, salmeterol and terbutaline by inhalation, as long as a therapeutic use exemption has been applied for and granted. In this context, the question arises of whether beta(2)-agonists have ergogenic benefits justifying the prohibition of these substances. In 17 of 19 randomised placebo-controlled trials in non-asthmatic competitive athletes, performance-enhancing effects of the inhaled beta(2)-agonists formoterol, salbutamol, salmeterol and terbutaline could not be proved. This is particularly true for endurance performance, anaerobic power and strength performance. In three of four studies, even supratherapeutic doses of salbutamol (800-1200 microg) had no ergogenic effect. In contrast to inhaled beta(2)-agonists, oral administration of salbutamol seems to be able to improve the muscle strength and the endurance performance. There appears to be no justification to prohibit inhaled beta(2)-agonists from the point of view of the ergogenic effects.

beta2-Agonists at the Olympic Games

The different approaches that the International Olympic Committee (IOC) had adopted to beta2-agonists and the implications for athletes are reviewed by a former Olympic team physician who later became a member of the Medical Commission of the IOC (IOC-MC). Steadily increasing knowledge of the effects of inhaled beta2-agonists on health, is concerned with the fact that oral beta2-agonists may be anabolic, and rapid increased use of inhaled beta2-agonists by elite athletes has contributed to the changes to the IOC rules. Since 2001, the necessity for athletes to meet IOC criteria (i.e., that they have asthma and/or exercise-induced asthma [EIA]) has resulted in improved management of athletes. The prevalence of beta2-agonist use by athletes mirrors the known prevalence of asthma symptoms in each country, although athletes in endurance events have the highest prevalence. The age-of-onset of asthma/EIA in elite winter athletes may be atypical. Of the 193 athletes at the 2006 Winter Olympics who met th IOC's criteria, only 32.1% had childhood asthma and 48.7% of athletes reported onset at age 20 yr or older. These findings lead to speculation that years of intense endurance training may be a causative factor in bronchial hyperreactivity. The distinction between oral (prohibited in sports) and inhaled salbutamol is possible, but athletes must be warned that excessive use of inhaled salbutamol can lead to urinary concentrations similar to those observed after oral administration. This article provides justification that athletes should provide evidence of asthma or EIA before being permitted to use inhaled beta2-agonists.

Inhaled beta2 agonists and performance in competitive athletes

OBJECTIVES

To provide an overview of the current literature on the use of inhaled beta2 agonists in non-asthmatic competitive athletes, and to assess the performance enhancing effect of inhaled beta2 agonists.

METHODS

Review of the literature.

RESULTS

Twenty randomised, placebo controlled studies (19 double blind, one single blind) were located. Only three studies reported a performance enhancing effect of inhaled beta2 agonists. However, methodological shortcomings were most likely responsible for these findings (for example, non-elite athletes, inconsistent results in different tests, subgroups with above-average responsiveness).

CONCLUSIONS

This review reveals that there is no ergogenic potential of inhaled beta2 agonists in non-asthmatic athletes. In view of the epidemiology of asthma in athletes and the considerable workload involved in provision of therapeutic use exemptions the inclusion of inhaled beta2 agonists on the list of prohibited substances should be reconsidered.

Na+-K+ pump stimulation improves contractility in damaged muscle fibers

Skeletal muscles have a high content of Na+-K+-ATPase, an enzyme that is identical to the Na+-K+ pump, a transport system mediating active extrusion of Na+ from the cells and accumulation of K+ in the cells. The major function of the Na+-K+ pumps is to maintain the concentration gradients for Na+ and K+ across the plasma membrane. This generates the resting membrane potential, allowing the propagation of action potentials, excitation-contraction coupling and force development. Muscles exposed to (1) high extracellular K+ or (2) low extracellular Na+ show a considerable loss of force. A similar force decline is elicited by (3) increasing Na+ permeability or (4) decreasing K+ permeability. Under all of these four conditions, stimulation of the Na+-K+ pumps can restore contractility. Following exposure to electroporation or fatiguing stimulation, muscle cell membranes develop leaks to Na+ and K+ and a partially reversible loss of force. The restoration of force is abolished by blocking the Na+-K+ pumps and markedly improved by stimulating the Na+-K+ pumps with beta 2-agonists, calcitonin gene-related peptide, or dbcAMP. These observations indicate that the Na+-K+ pumps are important for the functional compensation of the commonly occurring loss of muscle cell integrity. Stimulation of the Na+-K+ pumps with beta 2-agonists or other agents may be of therapeutic value in the treatment of muscle cell damage induced by electrical shocks, prolonged exercise, burns, or bruises.

Severe bone alterations under beta2 agonist treatments: bone mass, microarchitecture and strength analyses in female rats

AIMS

Beta2 adrenergic agonists are widely used in therapeutics and as doping agents by athletes. However, their effects on bone tissue, especially bone microarchitecture, remain poorly understood. Using three-dimensional (3D) microtomography, dual-energy X-ray absorptiometry, biomechanical testing and enzyme-linked immunosorbent assay, we evaluated the effects of two beta2 agonists, clenbuterol and salbutamol, on bone in growing rats.

METHODS

Twelve-week-old Wistar female rats (N = 39), divided in 3 groups, received during 6 weeks either salbutamol (4 mg/kg/day), clenbuterol (2 mg/kg/day) or normal saline (0.5 ml/kg/day) by subcutaneous injections.

RESULTS

After 6 weeks, the salbutamol and clenbuterol groups displayed lower bone mineral content (BMC), femoral length and cortical width than controls. Clenbuterol treatment further reduced bone mineral density. Bone microarchitecture was clearly altered by clenbuterol, as evidenced by lower trabecular number (-40.40%; P < 0.001), connectivity and trabecular bone volume (-42.85%; P < 0.001), leading to lower ultimate force. Clenbuterol significantly increased muscle mass (P < 0.01) and reduced fat mass when compared to controls. Salbutamol did not seem to have any effect on bone microarchitecture or body composition. Both beta2 agonists increased the bone resorption marker (C-terminal collagen crosslinks) without any change of a bone formation marker. At the end of the treatment, a drop in leptin was seen in the clenbuterol group only. Leptin levels were correlated with BMC (r = 0.69, P = 0.003).

CONCLUSION

These results confirm the deleterious effect of beta2 agonists on bone mass and show the negative effects of clenbuterol on trabecular bone microarchitecture. Bone loss occurred independently from muscle mass but was related to fat mass. A leptin-mediated effect on bone tissue seems likely. These pathophysiological effects may have important consequences in human therapeutics and doping.

Responses to bronchial challenge submitted for approval to use inhaled beta2-agonists before an event at the 2002 Winter Olympics

BACKGROUND

There has been an increase in the number and percentage of athletes competing in Olympic Games notifying use of beta2-agonists, from 1.7% at Los Angeles (1984) to 5.5% at Sydney (2000). For Salt Lake City (2002), the International Olympic Committee requested objective evidence to use beta2-agonists for asthma or exercise-induced asthma (EIA).

OBJECTIVE

The objective of this study was to evaluate the evidence submitted for approval to use a beta2-agonist.

METHODS

Objective evidence for asthma or EIA included (1) an increase of 12% or more of the predicted FEV1 in response to bronchodilator, (2) a reduction in FEV1 of 10% or greater from baseline in response to exercise or eucapnic voluntary hyperpnea, (3) a PD20 FEV1 to methacholine or histamine at a dose of less than 200 microg (2 mg/mL) or less than 1320 microg (13.2 mg/mL) for those taking inhaled corticosteroids for 3 months.

RESULTS

There were 165 applications. Of these, 147 (89%) included evidence of a challenge, bronchodilator response, or both, and 163 test results were submitted. One hundred thirty (5.2%) applications were approved. For those with positive responses, the median value (1) was 16.2% of predicted FEV1 for response to a bronchodilator (n = 13), (2) was a 15.9% decrease in FEV1 for response to a physical challenge (n = 36), and, (3) for PD20 FEV1, was 173 microg for response to a pharmacologic challenge (n = 45).

CONCLUSION

The analysis demonstrated that it is feasible to request objective evidence to justify use of beta2-agonists on the medical grounds of asthma or EIA.

Clenbuterol diminishes aerobic performance in horses

PURPOSE

The purpose of this 8-wk study was to examine the effect of therapeutic levels of clenbuterol on aerobic performance and hemodynamics associated with exercise.

METHODS

Twenty-three unfit Standardbred mares were divided into four experimental groups, clenbuterol (2.4 microg x kg(-1) body weight twice daily) plus exercise (20 min at 50% O2max; CLENEX; N = 6), clenbuterol only (CLEN; N = 6), exercise only (EX; N = 5), and control (CON; N = 6). All horses performed an incremental exercise test (GXT) to measure maximal oxygen consumption (O2max), blood lactate concentration, total plasma protein concentration, and hematocrit. Plasma volume, heart rate, right ventricular pressure (RVP), and pulmonary artery pressure (PAP) were measured before and after the treatment/training. Each horse also performed an exercise capacity test (ECT) in which they ran at their pretreatment O2max speed until exhausted.

RESULTS

There were no significant changes in blood lactate, total protein, or hematocrit for any group during either the GXT or ECT. CLENEX decreased (P < 0.05) O2max (-6.2%) and velocity to O2max (-10.0%), whereas both CLENEX and CLEN decreased (P < 0.05) in time to exhaustion (-20.5+/-4.7 and -20.9 +/- 5.6%). EX alone increased (P < 0.05) O2max (+6.5%), velocity to O2max (+10.0%), velocity to produces lactate concentration of 4 mmol (+13.5%), and time to exhaustion (+32.3 +/- 15.0%). Plasma volume was altered (P < 0.05) in CLENEX (-10%) and EX (+27%) but not in CLEN. Posttest recovery HR was higher (P < 0.05) at 2 min post-GXT in the CLENEX, CLEN, and CON compared with their pretest values; RVP remained elevated at 2 min of recovery in the CLEN and CON groups; however, in the EX, recovery HR and RVP had returned to pre-GXT levels by 2 min of recovery.

CONCLUSIONS

These data suggest that the combined effect of therapeutic levels of clenbuterol and training decrease aerobic performance and that the resultant reduction in plasma volume may affect improvements in cardiovascular function during recovery normally seen with exercise training.

The asthmatic athlete, inhaled beta agonists, and performance

INTRODUCTION

The large increase in the number of athletes who apply to use inhaled beta agonists (IBAs) at the Olympic Games is a concern to the medical community. This review will examine the use of IBAs in the asthmatic athlete, the variability that exists between countries and sport, and outline a plan to justify the use of these medications.

DATA SOURCES

Much of this article is a result of an International Olympic Committee (IOC) Medical Commission-sponsored meeting that took place in May 2001. Records of the use of IBAs at previous Olympics were reviewed. MEDLINE Searches (PubMed interface) were performed using key words to locate published work relating to asthma, elite athletes, performance, treatment, and ergogenic aids.

MAIN RESULTS

Since 1984 there have been significant increases in the use of IBAs at the Olympic Games as well as marked geographical differences in the percentage of athletes requesting the use of IBAs. There are large differences in the incidence of IBA use between sports with a trend towards increased use in endurance sports. There are no ergogenic effects of any IOC-approved IBA given in a therapeutic dose.

CONCLUSIONS

In many cases, the prescription of IBAs to this population has been made on empirical grounds. Beginning with the 2002 Winter Games, athletes will be required to submit to the IOC Medical Commission clinical and laboratory evidence that justifies the use of this medication. The eucapnic voluntary hyperpnea test will be used to assess individuals who have not satisfied an independent medical panel of the need to use an IBA.

Effects of aerosolized albuterol on physiologic responses to exercise in standardbreds

OBJECTIVE

To examine the effects of an aerosolized beta2-adrenoreceptor agonist, albuterol, on performance during a standardized incremental exercise test in clinically normal horses.

ANIMALS

8 Standardbred pacing mares.

PROCEDURE

Clinically normal horses, as judged by use of physical examination, hematologic findings, serum biochemical analysis, and airway endoscopy, were randomly assigned to 2 groups and were given 900 microg of albuterol via a metered-dose inhaler 30 minutes before beginning a standardized incremental exercise test in a crossover design with a 7-day minimum washout. Further examination included measurement of baseline lung mechanics, response to histamine bronchoprovocation, and bronchoalveolar lavage.

RESULTS

No significant differences (albuterol vs placebo) were seen for any incremental exercise test variables (ie, maximum oxygen consumption, maximum carbon dioxide consumption, respiratory quotient, treadmill speed at heart rate of 200 beats/min, or number of steps completed during an incremental exercise protocol). Mast cell percentage was significantly (r = -0.84) associated with the concentration of aerosolized histamine that evoked a 100% increase in total respiratory system resistance. No other direct correlations between bronchoalveolar lavage fluid cell types and any indices of exercise capacity or airway reactivity were found.

CONCLUSIONS AND CLINICAL RELEVANCE

Although no horse had exercise intolerance, 4 horses had airway hyperreactivity with bronchoalveolar lavage fluid mastocytosis; these horses may have been subclinically affected with inflammatory airway disease. In our study, albuterol did not enhance performance in 8 clinically normal racing-fit Standardbreds.