Regular exercise offers many benefits for people with asthma, including less frequent asthma symptoms, and improved heart and physical fitness. Swimming is a healthy form of aerobic exercise for people with asthma, especially for those whose symptoms are triggered by outdoor allergies or cold temperatures. The advantages of water-based exercise for people with asthma include breathing warm, humid air that often lacks or contains reduced levels of allergy-triggering substances found outdoors. Some research suggests that swimming regularly may improve lung function in people with asthma.
The air you breathe while swimming -- particularly indoors -- is lung-friendly. Warm, moist air doesn't irritate the lungs the way cold, dry air often does. Breathing humid air also cuts down on airway drying caused by an increased breathing rate during exercise. Airway drying can trigger asthma symptoms. Additionally, indoor pools don't expose you to outdoor allergens, such as pollen and mold spores. These substances are common symptom triggers for people with allergic asthma, which can make outdoor physical activity difficult.
Swimming is good way to improve cardiovascular fitness for people with asthma. An April 2013 "Cochrane Database of Systematic Reviews" article investigated the effect of swimming training on subjects younger than 19 with stable asthma. The authors concluded that swimming improves lung function, and heart and lung fitness. There was no evidence that swimming had negative effects on asthma control or flareups. However, the study could not address how swimming compares to other aerobic activities.
Lung Function Improvement
A July 2007 study in the "Scientific World Journal" examined effects of an indoor swimming and asthma education program in 65 adults with mild, persistent asthma on inhaled medications. After six months, the swimmers had improved lung function and decreased airway reactivity, compared to those who did not participate. A July 2014 "Cochrane Database of Systematic Reviews" article examined the medical research on the effects of water-based exercise on adults with asthma. While the authors found no evidence of potential harm, they were not able to draw any conclusions about potential benefits, because of the limited studies to date. More research is needed to determine the specific effects of swimming on adults with asthma.
Chlorine and Asthma
Chlorine, a chemical used to sanitize pool water, is often irritating to people with asthma and may cause difficulty breathing. When chlorine escapes from the water, it is diluted in the air and moved away from the water surface by circulating air. If you swim in an indoor chlorinated pool, a well-ventilated facility with high ceilings and ample space around the deck area can help reduce chlorine concentration in the air. Avoiding places with recirculating air, low ceilings or high pool sides may help prevent asthma flareups due to chlorine inhalation. Chlorine-free or saltwater pools, and outdoor swimming may be good alternatives if chlorine triggers your asthma symptoms.
A faster breathing rate during exercise may trigger asthma symptoms in some people. Be proactive and take asthma medications as directed to help prevent exercise-induced asthma symptoms. Keeping a quick-relief inhaler poolside is also advisable, in case you experience symptoms while swimming.
Swimming is not a treatment for asthma, and medications should always be used as prescribed. Talk to your doctor before starting a new physical activity.
Medical advisor: Shilpi Agarwal, M.D.