Jan 29, 2015The Beta on Asthma Meds
By Stan Reents
Stan Reents, PharmD, is a former healthcare professional. He holds Personal Trainer and Lifestyle Counselor certifications from the American Council on Exercise. He has also been certified as a tennis coach by the United States Tennis Association. He can be reached at: [email protected]
Asthma makes training and competing difficult… but not impossible. Athletes with asthma can, and do, achieve a high level of cardiorespiratory fitness (Freeman W. 1990). Elite athletes such as heptathlete Jackie Joyner-Kersee and swimmers Tom Dolan and Amy Van Dyken have won Olympic medals despite having asthma.
Still, it’s clear that asthma can hinder performance, particularly in certain events. Prolonged endurance events and sports performed in cold, dry air are the most challenging for athletes with asthma. Also, swimming can be a problem because the highly chlorinated air just above the water surface is thought to be a potential trigger for asthma attacks.
The incidence of exercise-induced asthma has been reported at 26 percent in elite runners (Helenius IJ, et al. 1998), 33 percent in cross-country skiers (Larsson K, et al. 1993), and 35 percent in figure skaters (Mannix ET, et al. 1996). One study reported an incidence of eight percent for “speed and power” athletes and 17 percent for long distance runners (Helenius IJ, et al. 1997). Cross-country skiing is probably the worst sport for an asthmatic. It combines three factors that are problematic: cold temperatures, dry air, and an endurance activity that raises respiratory rate over a prolonged period of time. Any one of these factors is a potential problem for an athlete with asthma.
HOW TO PREVENT EXERCISE-INDUCED ASTHMA
Obviously, the first strategy is to avoid the external conditions that provoke drying of the airways and bronchospasm. Unfortunately, this just isn’t possible for some events, such as swimming and cross-country skiing.
The most common medication used to prevent exercise-induced asthma is albuterol (this drug is known as “salbutamol” outside the U.S.). Albuterol can be administered systemically (as oral tablets or syrup), but the most common method is by inhalation via a metered-dose inhaler (MDI).
Albuterol belongs to a category of drugs known as “beta-2 agonists.” The beta-2 agonists relevant for discussion here include: • albuterol/salbutamol (short-acting) • formoterol (long-acting) • salmeterol (long-acting) • terbutaline (short-acting)
BETA-2 AGONISTS ARE BANNED SUBSTANCES
The four agents listed above are the only beta-2 agonists allowed for use by many sports governing bodies. The World Anti-Doping Agency (WADA) prohibits the use of all beta-2 agonists during Olympic competition when administered systemically, but does allow their use via inhalation. Many other sports governing groups have adopted the WADA rules on these drugs. The NCAA Banned Drug Classes List for 2007-08 states: “Use of beta-2 agonists is permitted by inhalation only.”
If a college athlete does have asthma, he or she can receive permission to use beta-2 agonists, but only via inhalation. This requires the submission of a “Therapeutic Use Exemption.”
ARE BETA-2 AGONISTS ERGOGENIC?
Beta-2 agonists are banned from use during competition because they are considered stimulants. Clenbuterol, a beta-2 agonist not approved for human use in the U.S., is classified as an anabolic agent. Dozens of studies have been conducted to assess whether beta-2 agonists enhance performance. Unfortunately, questions about their ergogenic potential cannot be answered with a simple “yes” or “no.”
If these drugs are administered systemically, the research is pretty clear that there is a high likelihood of enhanced performance. However, if these drugs are administered by inhalation, things are a bit more confusing. Most of the research shows that, when administered by inhalation, beta-2 agonists do not enhance performance. One researcher feels so strongly about this that he proposes beta-2 agonists be removed from the list of banned substances (Kindermann W. 2007).
On the flip side, in 2004, Marlene van Baak and researchers from the Netherlands conducted a study of salbutamol in non-asthmatic athletes. They found that an 800-mcg dose of salbutamol inhaled 30 minutes prior to testing did improve performance, as measured on a cycle ergometer (van Baak MA, et al. 2004).
Why did they find benefit when so many other researchers did not? Van Baak and colleagues designed their study to measure how long it took to complete a fixed amount of work. Most of the other researchers measured how long an athlete can sustain intense exercise before exhaustion. This is a subtle, but very significant, difference in study design. The van Baak study more closely approximates what occurs in a race: The distance (the “amount of work”) is fixed and the athlete races the clock, not his or her own physiology.
Regrettably, some athletes abuse the system. They falsely claim to have asthma so that they can obtain medical clearance to use beta-2 agonists prior to competition. Triathletes appear to be the worst offenders, so much so that in 1999 ESPN.com published a story about the widespread abuse of inhalers prior to races (“Triathletes Suck,” Tom Farrey, ESPN.com, June 14, 1999). At that time, the International Triathlon Union reported that 98 percent of their registered athletes claimed to suffer from asthma. This is compared to a worldwide prevalence of asthma of around 12 to 15 percent.
It doesn’t make sense for athletes to abuse these drugs when the preponderance of evidence shows that, when administered by inhalation, beta-2 agonists are not ergogenic. However, there exists a possibility that van Baak and colleagues have uncovered reasons why so many previous studies failed to identify a performance-enhancing effect.
Will major sports governing bodies reverse their decision on the classification of beta-2 agonists? Only time will tell.
Freeman W, Williams C, Nute MG. Endurance running performance in athletes with asthma. Journal of Sports Science and Medicine, 1990;8:103-117.
Helenius IJ, Tikkanen HO, Haahtela T. Association between type of training and risk of asthma in elite athletes. Thorax, 1997;52:157-160.
Helenius IJ, Tikkanen HO, Haahtela T. Occurrence of exercise-induced bronchospasm in elite runners: dependence on atopy and exposure to cold air and pollen. British Journal of Sports Medicine, 1998;32:125-129.
Kindermann W. Do inhaled beta-2-agonists have an ergogenic potential in non-asthmatic competitive athletes? Sports Med 2007;37:95-102.
Larsson K, Ohlsen P, Larsson L, et al. High prevalence of asthma in cross country skiers. Br Med J 1993;307:1326-1329.
Mannix ET, Farber MO, Palange P, et al. Exercise-induced asthma in figure skaters. Chest 1996;109:312-315.
Storms WW. Exercise-induced asthma: diagnosis and treatment for the recreational or elite athlete. Medicine and Science in Sports and Exercise, 1999;31:S33-S38.
van Baak MA, de Hon OM, Hartgens F, et al. Inhaled salbutamol and endurance cycling performance in non-asthmatic athletes. International Journal of Sports Medicine 2004;25:533-538.