Kate Johnson

October 29, 2015

MONTREAL — In relatively unfit adults, 12 weeks of aerobic exercise significantly improved asthma control, according to preliminary results from the randomized Impact of Aerobic Exercise on Asthma Morbidity (Ex-Asthma) study.

This finding suggests that exercise could be used as an adjunct to pharmacotherapy in this population, said lead investigator Simon Bacon, PhD, from Concordia University and Hôpital du Sacré-Coeur in Montreal, Quebec, Canada.

"Historically, people have built this sort of myth that exercise for people with asthma should be discouraged, but anecdotally, when patients do exercise, they tend to report feeling better," he explained.

The study was presented as a late-breaking abstract here at CHEST 2015: the American College of Chest Physicians Meeting.

Dr Bacon was involved in a recent study showing that patients with asthma reporting higher levels of physical activity had better control of their disease (BMJ Open Respir Res. 2015;2:e000083).

In the current study, 33 patients with physician-diagnosed asthma were randomly assigned to receive 12 weeks of supervised aerobic activity and 33 were assigned to receive usual care. Mean age was 49 years. The primary outcome was postexercise asthma control, measured with the Asthma Control Questionnaire (ACQ) score.

All patients had stable but symptomatic disease, indicated by a baseline score of 2.0 on the 7-point ACQ scale, and were treated with inhaled corticosteroids, at a per day equivalent of at least 250 μg of fluticasone.

Patients were excluded from the study if they had comorbidities, were unable to exercise, or were obese "because of the interesting relationship between weight and asthma, and we did not want to confound the findings," Dr Bacon explained.

In general, the cohort was classified as "sedentary," performing less then 60 minutes of planned physical activity per week. "This is not a particularly fit population," he pointed out.

The exercise intervention involved three supervised 1-hour sessions each week that consisted of a 10-minute warm-up, 40 minutes of aerobic exercise titrated at 50% to 75% of heart rate reserve for the first 4 weeks and 70% to 85% from weeks 5 to 12, and a 10-minute cool-down. Bronchodilators were used 15 minutes before each session, and heart rate checks were performed three times during the session.

For usual care, patients were encouraged to maintain their sedentary lifestyle for the 12-week study period and were contacted every 4 weeks to check on symptoms, medication, and exercise levels. They were given the opportunity to participate in the exercise intervention at the conclusion of the study.

Asthma Control

Asthma control was significantly better in the exercise group than in the usual-care group (ACQ score, 1.34 vs 1.82; P = .008).

In addition, the weekly use of short-acting bronchodilators was nearly three times less in the exercise group than in the usual-care group (P = .003). However, maximal oxygen consumption, the methacholine challenge test, spirometry, and sputum inflammation biomarkers did not differ between groups.

There was also no difference in body mass index between the exercise and usual-care groups, but a significant difference was seen in change in waist circumference (P = .04). "This was really an attenuation of the increase we saw in the control group," said Dr Bacon.

 
Even in a nondepressed group, we're seeing some really interesting improvements in mood. Dr Simon Bacon
 

Exercise also had a psychological benefit. Beck Depression Inventory scores decreased 4 points in the exercise group. "And this is a group that was not depressed," said Dr Bacon. "So even in a nondepressed group, we're seeing some really interesting improvements in mood."

This study "nicely confirms previous results summarized in our systematic review and meta-analysis," said Christina Spengler, PhD, MD, from ETH Zurich. Her team showed that most of the seven studies analyzing the use of asthma medication reported a reduction in medication intake with exercise, whereas two studies reported none (Sports Med. 2013;43:1157-1170).

The effect of exercise reported by Dr Bacon and his colleagues would not be considered clinically meaningful because it is suggested that 0.5 is "the minimal clinically relevant difference in ACQ," Dr Spengler explained.

"Unfortunately, the presented improvements in ACQ and short-acting β-agonist use cannot be explained by improvements in any of the asthma-specific impairments assessed," she said. For instance, "there were no changes in bronchial hyper-reactivity, lung function, or inflammation," but such improvements have been shown in other studies.

"Therefore, from a mechanistic point of view, the physiological basis for the observed improvements remains unclear," she pointed out.

Two other aspects of the results are also difficult to explain, she added.

"Why did the exercise training subjects — a sedentary group before the study — have no significant improvement in maximal oxygen consumption after 3 months of endurance training?" Dr Spengler asked. "This is very unexpected. Was the load not high enough for their fitness level?"

"And why did waist circumference increase in the control group? This is also quite unexpected," she added.

"It is exciting to see that other groups are beginning to show that exercise really improves asthma treatment," said Celso Carvalho, PhD, from the University of São Paulo School of Medicine in Brazil.

Dr Carvalho, who has published extensively in the field of asthma and exercise, told Medscape Medical News that his group has previously shown many of the findings reported by Dr Bacon's team.

"Their finding of no change in spirometry is surprising, since there are two meta-analyses demonstrating this," he said (Br J Sports Med. 2000;34:162-167 and Cochrane Database Syst Rev. 2013;30:CD001116).

However, "I expect that they would find a reduction in the methacholine challenge test and sputum inflammation biomarkers with an increase in their sample size," Dr Carvalho added.

Dr Bacon reports financial relationships with GlaxoSmithKline, AbbVie, Schering-Plough, Merck, Kataka Medical Communication, and Novartis. Dr Spengler and Dr Carvalho have disclosed no relevant financial relationships.

CHEST 2015: American College of Chest Physicians Meeting. Presented October 26, 2015.

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