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 Researchers found that about a quarter of competitors in swimming
events had verified asthma, although it was more common among
athletes from some parts of the world than others.
The intensity of swimmer training, or long hours spent in the water,
may expose swimmers to more chlorine byproducts compared to divers
or other athletes who spend less time breathing just at the water’s
surface, experts said.
A long-term study would help distinguish “between athletes with
asthma who self-select to swimming and those who have asthma as a
result of exposure to endurance training practices,” said lead
author Dr. Margo Mountjoy of McMaster University Waterloo campus in
Ontario, Canada.
Mountjoy is a practicing sports physician in aquatics and a member
of a Therapeutic Use Exemption Committee for the International
Olympic Committee and the World Anti-Doping Association.
She and her coauthors studied objective evidence of asthma among all
aquatic athletes who competed at the 2005, 2007 and 2009 FINA World
Championships and the 2004 and 2008 Olympic Games in swimming,
synchronized swimming, diving, water polo and open water swimming
events.
Athletes with asthma were required to show proof of airway
obstruction with a clinical test in order to use their inhaled
medications, which are otherwise prohibited during competition.
Most years, swimming events had more participants with asthma or
other airway obstruction than other aquatic events. At the 2008
Olympic Games, an exception, the synchronized swimmers and open
water swimmers also had high asthma rates.
Each year, between 12 and 25 percent of swimmers had asthma. In
2008, almost 25 percent of swimmers, 26 percent of open water
swimmers and 22 percent of synchronized swimmers had asthma.
In general, more athletes in endurance events like triathlon,
pentathlon or cycling had asthma than those in nonendurance sports
like fencing, volleyball or table tennis, the authors note.
Asthma was more common in aquatic endurance sports, which included
swimming, open water swimming and synchronized swimming, than in
nonedurance events like diving, they write in the Journal of Allergy
and Clinical Immunology.
“I was not surprised to find that swimmers had a high prevalence of
asthma,” Mountjoy told Reuters Health by email. “What was surprising
for me to find was that there were significant differences between
the endurance and non-endurance sports, as well as the distinct
geographical distributions.”
More athletes from Oceania, Europe and North America had asthma than
those from Asia, Africa and South America, the authors found.
“It was also interesting to find that although asthma is more
prevalent in women than in men in the general population, this
gender difference was not evident in the elite aquatic population,”
Mountjoy said.
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Some postulate that the chlorine-derived chemicals in the air of
aquatic training facilities may cause asthma, she said.
“It is exposure to the chlorine and chlorinated compounds that is
responsible for the changes in airway hyper responsiveness,” said
Dr. Don McKenzie, who studies respiratory exercise physiology at the
University of British Columbia in Vancouver.
The more swimming you do, the more the risk increases, and elite
athletes spend the most time with the chemicals, McKenzie, who was
not involved in the new study, told Reuters Health by email.
“If you swim in non-chlorinated pools, lakes, ocean etc. then the
risk disappears,” he said.
Alfred Bernard of the Catholic University of Louvain in Brussels,
Belgium, agrees the chlorine-based oxidants building up at the
surface of pools that the elite swimmers actively inhale penetrate
deeply in the lungs and probably cause asthma.
Divers and water polo players may hyperventilate less than elite
endurance swimmers, breathe more through the nose and do not
continuously inhale the chlorine-laden air just above the water’s
surface, which may explain the decreased prevalence of asthma,
Bernard told Reuters Health by email.
Historically, asthmatic children may have been encouraged to
practice swimming and may go on to other aquatic disciplines,
Mountjoy said.
“Swimmers should be aware that if they have a chronic cough,
shortness of breath, or wheezing, they should seek medical attention
for appropriate testing and treatment,” she said. “They should also
ensure that their training environment has appropriate ventilation
with respect to air quality.”
Asthmatic swimmers were no more or less likely to earn medals than
other athletes, Mountjoy noted, which means it may not affect
performance if properly treated.
“The health benefits of swimming are numerous and the risk of
developing asthma at the elite level does not negate these other
important health benefits,” she concluded.
SOURCE: http://bit.ly/1CVyxUz
Journal of Allergy and Clinical Immunology, online March 24, 2015.
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