New study suggests they don't help... even if you have exercise-induced asthma.
By Alex Hutchinson Friday, October 11, 2013, 12:00 am
The topic of asthma meds and performance enhancers has sparked controversy now and then over the past decade, for example when it was revealed that U.S. Olympic team doctors were diagnosing new cases of exercise-induced asthma on the spot at the 2004 Olympics so that the athletes (including marathon silver medalist Meb Keflezighi, apparently) could use inhalers prior to competition. And there are some puzzling statistics, like the fact that 17% of the cyclists at the 2008 Olympics were officially diagnosed as asthmatic -- and those athletes won a disproportionate 29% of the individual medals.
So are asthma medications a performance enhancer -- even (or perhaps especially) in people who don't actually have asthma? While it might seem obvious from the circumstantial evidence, scientists haven't actually found this to be the case. In tests of healthy people, the meds don't seem to improve endurance performance. Now a new study, just published in the British Journal of Sports Medicine by Michael Koehle's Environmental Physiology group at the University of British Columbia, takes things a step further by testing both healthy and asthmatic cyclists, with surprising results.
The study involved 48 well-trained male cyclists (VO2max > 60 ml/kg/min); before the study started, they were all screened for exercise-induced asthma, and 14 of them tested positive (all but one had been previously diagnosed). They all did two 10-km cycling time trials, which take about 15 minutes -- a combination of intensity and duration that's thought to offer the toughest challenge to an athlete's respiratory system. An hour before each time trial, they inhaled either salbumatol or a placebo; neither they nor the researchers knew which one they'd been given on which occasion.
The results? Lung function did improve in both the asthma and non-asthma group -- but that didn't translate into any improvement in time-trial performance. The surprise here is that the increase in lung function didn't translate to better performance even for the group with exercise-induced asthma. That doesn't mean salbutamol doesn't work -- it's highly effective as relieving the acute symptoms of an asthma attack. But it means that:
(1) Under normal circumstances, lung function simply isn't a limiting factor in exercise performance (or at least, in this particular length and type of exercise). Yes, salbutamol increases lung function -- but whatever factors are slowing you down, it's not the ability of your lungs to get air in and out that prevents you from going faster. (Is it the diffusion of oxygen from the lungs into the blood? The ability of the heart to pump blood to the muscles? The rate at which the muscles can use the oxygen provided to them? Or none of the above? That's a debate that's still raging.)
(2) The subjects diagnosed with exercise-induced asthma had "normal" lung function during the time trial even with no salbutamol. One of the factors mentioned in the paper is that the exerimental protocol involved a thorough warm-up prior to the time trial, which is known to protect against subsequent asthma attacks. For many people, that might be good enough.
Of course, there are still questions -- would the results have been the same in the heat and humidity of the Athens or Beijing Olympics? Would they have been the same if the time trials were repeated 100 times (i.e. is warm-up a good but imperfect way of avoiding respiratory symptoms)?
And there's still the lingering question of why asthmatic athletes seem to win more medals than their non-asthmatic competitors. One possibility: the athletes most likely to be diagnosed with asthma are those coming from well-funded programs with lots of support, some (but not all) of which has a material impact on performance.
