Exercise tolerance and potential reduced work capacity in children with asthma are still a subject of debate. Results from trials with regard to the possible benefits and risks of exercise in asthmatic children and adolescents have shown contradictory results because exercise may trigger allergic systemic, cutaneous and respiratory symptoms, such as exercise-induced asthma.

However, on the other hand, regular exercise and participation in sports are considered useful in the management of asthma, since physical training improves cardiopulmonary fitness, neuromuscular coordination, self confidence and health-related quality of life.1,2 Regular physical activity appears to induce beneficial immunological changes, thereby reducing allergic inflammation.3 Oxygen consumption, maximum heart rate and work capacity are all increased significantly during exercise4 and asthmatics, during exercise, present higher tidal volumes and lower respiratory rates compared to healthy controls.5 In addition, physical training leads to significant reductions in the use of both inhaled and oral steroids.6

There was also found an association between asthma and both obesity and low levels of physical activity.7 Moreover, asthma impacts negatively on mental health, while higher levels of physical activity improves it.7 There is solid evidence to reassure physicians on the work capacity of asthmatics and to encourage them to take up sports.5

Data about limited physical fitness in asthmatic children and adolescents are contradictory. The aim of this study was to determine any differences between the level of physical activity of controlled allergic patients and their healthy peers.

A total of 323 questionnaires were collected. After using exclusion criteria, a final sample of 155 controlled asthmatic and 158 healthy controls was obtained (313 valid questionnaires).

The median age of allergic patients was 11 years (5–18) and 62.6% (97) were male. Healthy controls had a median age of 10 years (8–18) and 46% (73) were males.

With regard to question 1 (how often the child had played each of the sports in the previous week), results are listed in Table 1. We found statistically significant differences in skipping (p=0,000), in-line skating (p=0,012), cycling (p=0,005), aerobics/hip-hop (p=0,002), swimming (p=0,000), ballet/dance (p=0,042), football (p=0,017), volleyball (p=0,024), athletics (p=0,023) and martial arts (p=0,024).

In relation to questions 2–7 (Table 2), which define the pattern of physical activity for these children, the only differences found concerned performance in physical education classes (healthy children tend to be more active; p=0,011) and in after-school sports activities (healthy children tend to play more sports between 6 and 10 p.m.; p=0,036).

No significant differences were found regarding exercise distribution by days of the week (question 8; Table 3).

Asthmatic patients had an average final score of 2,40 (±0,7; 0,85–4,62) and healthy controls had a mean score of 2,48 (±0,62; 1,09–4,42). There were no differences in the overall level of physical activity, estimated by PAQ score, between asthma and healthy children (2,40 (±0,7) vs. 2,48 (±0,62); p=0,32).

For this particular sample, PAQ was a practical method of collecting activity data, mainly because it is based on the child's self-report of activities in the previous 7 days. Evidence was provided that supported PAQ as a reliable and valid measure of general physical activity levels in children during the school year.9 As a 7-day report, PAQ has shown to correlate better with objective measures of activity in children whose memories are often questionable.10

A limitation of this questionnaire is the fact that it was designed for the Canadian population, and so it includes some sports which are not common in Portugal, such as rugby or American football. This may have influenced the results to some extent. However, the most popular Portuguese sports (such as football, athletics or swimming) are included in this questionnaire.

Children were attending routine appointments rather than emergency visits and those who had had an exacerbation in the previous six months were excluded. Furthermore, all children who answered “yes” to question 9 (“Have you been ill or has anything prevented you from taking your normal exercise?”) were also excluded.

Despite the fact that the majority of parents of asthmatic children considered that their child's disease was a barrier to physical activity,11 our results suggest that well controlled asthmatic patients can achieve a similar level of exercise performance to that of healthy children. The literature tends to be in agreement with our outcome, with some reports saying that asthmatic children are as physically fit and as physically active as healthy children.2,5,12,13 However, a number of studies have found that asthmatic children and adolescents are significantly less likely to engage in vigorous physical activity and are less physically fit than healthy individuals.7,14–19 Our interpretation is that our study includes only those situations of controlled asthma, while some of the mentioned references also cover patients with uncontrolled asthma. We emphasize that, despite the fact that the overall level of physical activity was the same in asthmatic and non-asthmatic children, playing sports outside school and taking part in team sports was less common among asthmatics.

The level of physical conditioning was found to be the main determinant of exercise tolerance for children with controlled asthma.5 Although children with well controlled asthma can achieve a level of physical performance similar to that of healthy children, the fear of inducing dyspnea inhibits many of them from taking part in physical activity and a low level of regular physical activity in turn leads to a low level of physical fitness.1 The consensus in the literature suggests that both parents and children with asthma are concerned about the effects of exercise and perceive asthma as a barrier to sports participation.7 Reduced participation may be influenced by organizational policies, family illness beliefs, health care advice and inaccurate symptom perception. Schools and families are often reluctant to encourage children to take part in physical education or normal play activity as a result of ignorance or misunderstanding of medical advice.11 Many young people themselves appear to accept sub-optimal control of symptoms and frequently misinterpret healthy shortness of breath when exercising with the symptoms of an impending asthma attack.2,20

In our study, both groups showed a low overall physical activity level (average 2.4), when compared to other populations. For example, in an American study with almost 500 adolescents, the mean activity score for boys and girls combined was 3.2110 and another study estimated a mean activity score of 3.29 for boys and of 3.16 for girls.21 This has to do with cultural issues; without doubt there is less access to sport in Portugal than in many other countries.

In relation to the various types of physical activity (Table 1), we believe that the differences found can be explained by the small take up in either group. In our population, besides the low physical performance score presented, only a few children in either group played sports outside school. Lack of participation in physical activity by children and adolescents is not surprising given that physical activity levels are known to be falling among young people in most industrialized nations. These rates fall even further as children reach adolescence, particularly in teenage girls.20

We found no difference between the level of physical activity of children and adolescents with controlled asthma and their healthy peers. In both groups the physical performance level was low. We highlight the need to promote exercise within pediatric asthma care, in order to protect both mental and physical health. The families of asthmatic patients should be informed about the benefits of physical exercise in well-controlled asthma.

Protection of human and animal subjects. The authors declare that no experiments were performed on humans or animals for this study.

Confidentiality of data. The authors declare that they have followed the protocols of their work center on the publication of patient data and that all the patients included in the study received sufficient information and gave their written informed consent to participate in the study.

Right to privacy and informed consent. The authors have obtained the written informed consent of the patients or subjects mentioned in the article. The corresponding author is in possession of this document.

The authors have no conflicts of interest to declare.