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Krefting Research Centre, Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Göteborg, SwedenThe OLIN Studies, Department of Medicine, Sunderby Central Hospital of Norrbotten, Luleå, Sweden
Department of Medical Sciences, Respiratory Medicine and Allergology, Uppsala University, Akademiska sjukhuset, 75185 Uppsala, SwedenDepartment of Neuroscience, Physiotherapy, Uppsala University, Sweden
Having asthma has in previous reports been related to a lower physical activity level. At the same time the prevalence of asthma among elite athletes is high. The aim of this study was to investigate the association between physical activity level and asthma.
Methods
A postal questionnaire was completed by 25,610 individuals in Sweden. Current asthma was defined as having had an asthma attack during the last 12 months or current use of asthma medication. The participants were asked how often and for how many hours a week they were physically active.
Results
In the population 1830 subjects (7.1%) had current asthma. There was no significant difference in the proportion of subjects that reported being inactive or slightly physically active between asthmatic and non-asthmatics (57 vs. 58%) while the proportion of subjects that were vigorously physically active (≥2 times a week and ≥7 h per week) was higher among the subjects with asthma (6.7 vs. 4.8%, p < 0.0001). Being vigorously physically active was independently related to current asthma (OR (95% CI)) 1.40 (1.11–1.77)), wheeze (1.39 (1.17–1.65)), wheeze and breathlessness (1.68 (1.38–2.04)), and wheezing without having a cold (1.39 (1.13–1.71)). The association between being vigorously physically active and wheeze was significantly stronger in women compared to men.
Conclusions
There was no difference in the proportion of subjects with a reported low level of physical activity between asthmatics and non-asthmatics. Health care professionals should, however, be aware of the increased prevalence of asthma and asthma-related symptoms in vigorously physically active subjects.
American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise.
]. Individuals who are physically active are more likely to have a better overall health-related quality of life and a better perceived health status than those who are not. The association between physical activity and health is evident for all-cause mortality, incidence and mortality of cardiovascular diseases including coronary heart disease, and for the incidence of type 2-diabetes [
]. Avoiding a sedentary lifestyle during adulthood prevents cardiovascular disease independently of other risk factors and substantially expands the total life expectancy [
The types and amounts of physical activity needed for health promotion and disease prevention include recommendations of moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on five days each week and vigorous-intensity aerobic physical activity for a minimum of 20 min on three days each week [
American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise.
American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise.
There are studies indicating that subjects with asthma may be less physically active due to their disease. Two epidemiological studies reported that subjects with asthma met the physical activity recommendations to a lower extent than subjects without asthma [
] as a result of a physical training programme. However, even if it is accepted that exercise has positive effects, or at least no deleterious effects, in asthma [
The association between BMI, vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema in children and adolescents: ISAAC phase three.
Exercise-induced asthma, respiratory and allergic disorders in elite athletes: epidemiology, mechanisms and diagnosis: part I of the report from the Joint Task Force of the European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA2LEN.
The aim of this study was to explore the level of physical activity in subjects with asthma and compare this to subjects without asthma, with the hypothesis that subjects with asthma are less physically active than subjects without asthma. Furthermore, we studied whether the prevalence of asthma is higher among those who are vigorously physically active compared to those who are less physically active.
Methods
Study design and study population
This cross-sectional study was conducted through a postal questionnaire which was part of the Global Allergy and Asthma European Network (GA²LEN) survey in 2008. In Sweden, the questionnaire was sent to randomly selected subjects in the ages 16–75 years living in the cities of Stockholm, Gothenburg, Uppsala and Umeå, Sweden [
]. In total, 45,000 questionnaires were distributed and 26,647 participants responded, giving a response rate of 59%. Ethical approval was granted by the Regional Ethical Review Board in Uppsala, Sweden.
GA2LEN questionnaire
The GA²LEN postal questionnaire contained 23 questions [
]. The questions covered: gender, age, asthmatic symptoms, asthma, rhinitis, eczema, smoking and certain work exposures. In Sweden 17 extra questions were added including questions on weight, height, environment, educational level, chronic diseases, sleeping habits and physical activity [
]. Body mass index (BMI) was calculated using the answers on weight and height. Overweight was defined as body mass index (BMI) of 25–30 kg/m2. Obesity was defined as a BMI of >30 kg/m2.
Asthma
Current asthma was defined as a positive answer to either “Have you suffered from an asthma attack during the last 12 months?” or “Do you currently use any asthma medication including inhalers, sprays or pills?” [
]. The present investigation only included subjects who had answered both of the questions above (n = 25,610).
The questions on asthma-related symptoms during the last 12 months included: (i) wheezing or whistling in the chest; (ii) wheezing in combination with breathlessness; (iii) wheezing when not having a cold; (iv) waking up with chest tightness at any time in the last 12 months; (v) being woken up by shortness of breath, and (vi) waking up by an attack of coughing.
Physical activity
Physical activity was estimated by asking participants how often (frequency) and for how many hours (duration) a week they exercised so much that they got out of breath or became sweaty [
] (Table 1). Based on exercise levels, the participants were divided into four groups. The physically inactive group included subjects who reported frequency of physical activity “once a month” or less and reported duration of 0 h per week. The “moderately physically active” group included subjects physically active at least twice a week and at least two hours a week. The “vigorously physically active” group included subjects that were physically active at least twice a week and at least seven hours a week. The remaining formed the group “slightly physically active”. The definition of the moderately and vigorously physically active groups were made to correlate as closely as possible with the international recommendations on physical activity in adults [
American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise.
Table 1Distribution of the subjects in different activity levels. The numbers in the boxes correspond to the number of subjects in each activity category.
Table 1Distribution of the subjects in different activity levels. The numbers in the boxes correspond to the number of subjects in each activity category.
Tobacco
Smoking was assessed by the questions “Have you ever smoked one or more cigarettes per day for more than one year?” and “Have you smoked at all during the last month?” The subjects were categorized into never-, ex- and current smokers.
Educational level
Educational level was categorized according to the following three levels: nine-year elementary school, high school graduation and academic degree.
Comorbidity
Rhinitis was defined as a positive answer to both “Do you have any nasal allergies including hay fever?” and “Have you been troubled by nasal allergies in the last 12 months?”
Hypertension and diabetes was defined as currently taking medication against hypertension and diabetes, respectively.
Data analysis
STATA version 12 (STATA Corp, College Station, Texas, USA) was used for statistical analyses. Univariate analyses using Chi2 tests were used when comparing physical activity levels and other variables between subjects with and without asthma. Multivariable logistic regression models were used when studying independent association between physical activity and asthma after adjusting for potential confounding factors such as gender, age, BMI, smoking, rhinitis, educational level, co morbidities and centre. A p-value of <0.05 was regarded as statistically significant.
Results
Characteristics of the study population
The prevalence of current asthma in this general population was 7.1%. The group with current asthma was younger, had a higher proportion of females, lower level of education, higher prevalence of rhinitis, obesity, diabetes and hypertension than the group without asthma (Table 2).
Table 2Characteristics of the study population (%).
There was no significant difference in the proportion of subjects who reported being inactive or slightly physical active between subjects with and without asthma (57 vs. 58%, p = 0.12). There were, however, a significantly higher proportion of vigorously physically active persons in the asthma group compared to the group who did not have asthma (Fig. 1). These results remained after adjustments for gender, age group, BMI group, smoking and rhinitis.
Figure 1Physical activity and current asthma. Prevalence (%) presented above the bars.
Almost 20% of the studied population was physically inactive. The subjects in the inactive group had a higher BMI, were more often smokers or ex-smokers, had a lower educational level, and were more likely to have diabetes and high blood pressure compared to the other groups. The “vigorously physically active” group consisted of more males than females and the subjects were younger than in the other three groups (Table 3).
Table 3Distribution of personal, socioeconomic, smoking and comorbidity variables across levels of physical activity (%).
Multivariable analysis of risk factors for current asthma and asthma symptoms
Being in the vigorously physically active group was independently related to having asthma (Table 4). Other independent risk factors for having current asthma were female gender, rhinitis, being overweight or obese, being a former smoker and having diabetes. Having a college education and being of older age were related to a lower probability of having asthma (Table 4).
Table 4Independent association between physical activity and other characteristics towards having current asthma.
Being vigorously physically active was independently related to increased risk of wheeze, wheeze and breathlessness, and wheeze without having a cold (Table 5). The risk of wheeze without having a cold was higher in the physically inactive group while being moderately physically active was independently associated to less night-time chest tightness and night-time attacks of breathlessness.
Table 5Independent association between asthma symptoms and physical activity (adjusted odds ratio
The association between being vigorously physically active and wheeze was stronger in women than men (Fig. 2), whereas no significant interaction was found between subjects with and without asthma regarding the association between physical activity and wheeze. The significant gender interaction in the association between being vigorously physically active and wheeze remained statically significant also when including height in the model. No significant gender interaction was found between being vigorously physically active and current asthma (p = 0.19).
Figure 2Adjusted odds ratio (OR) and 95% for the association between vigorous physical activity and wheeze in men and women.
Responders had a higher mean age than non-responders (mean ± SD: 45 ± 16 vs. 38 ± 14 years) and the response rate was higher in women than in men (65 vs. 53%).
Discussion
The main result of the present study is that almost 60% of the participants in the GA2LEN survey in Sweden had an activity level that was below what is needed for health promotion and disease prevention with no difference between non-asthmatics and asthmatics. Subjects with asthma were more often vigorous physical active than subjects without asthma, and being vigorously physically active was associated with having respiratory symptoms, especially in women.
Our results, showing that subjects with asthma are at least as physically active as subjects without asthma, are in accordance with a study using data from the 1994–1995 Canadian National Population Health Survey [
]. In contrast, an epidemiological study from the US found that subjects with asthma were less physically active and engaged in vigorous physical activities to a lesser extent than those without asthma [
] which might explain why previous studies show asthmatic persons to be less active. Following the development of improved asthma medications, current guidelines now recommend patients with asthma to be physically active [
]. Our result suggests that asthma is not a significant obstacle to the general physical activity in the Swedish population.
Almost 20% of the participants were physically inactive, i.e. were never physically active or physically active ≤ once a month. They had a higher BMI, were more often smokers and had a higher prevalence of diabetes and hypertension compared to those who were more physically active. It has been shown that the amount and duration of prolonged sitting is detrimental and increases the risk of mortality [
]. Thus, this group of subjects needs attention and advice in becoming more physically active.
Wheeze and current asthma were over-represented in the most physically active group which is in line with two recent studies reporting negative effects of vigorous physical activity on asthma symptoms [
The association between BMI, vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema in children and adolescents: ISAAC phase three.
]. The explanation to the findings may be that subjects who exercise vigorously have more symptoms from their asthma. Indices of wheeze, but not of night-time asthma symptoms, were increased in the most physically active group. This indirectly suggests that the wheezing symptoms were experienced during daytime activities, i.e. during physical activity. It is also possible that vigorous exercise might cause asthma. The increased and prolonged increased ventilation in athletes that perform vigorous exercise causes dehydration of the mucosa and can lead to epithelial damage [
]. Increased airway inflammation, measured as exhaled nitric oxide, has been reported in a recent study in vigorously active adolescents without asthma [
] reported an increase in eotaxin levels in exhaled breath condensate following intensive exercise, which was linked to the increase of eosinophilic airway inflammation. It is also possible that the environment that the activity is performed in increases the risk for asthma. For example cold air, air pollution such as chlorine from swimming pools, and airborne allergens may be of importance for the development of asthma [
Exercise-induced asthma, respiratory and allergic disorders in elite athletes: epidemiology, mechanisms and diagnosis: part I of the report from the Joint Task Force of the European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA2LEN.
The association between vigorous physical activity and wheeze was more often found in women in the present study. This is in line with the findings of Verlaet et al. who reported that vigorous physical activity was related to worsening of asthma control in women but not in men [
]. The association remained also after adjusting for height which indicated that this difference is probably not related to gender difference in lung size. In another analysis from the present data set we found that smoking was a stronger risk factor for wheeze in women than in men [
]. It remains to be investigated whether there is a common underlying pathophysiological mechanism that explains why women are more susceptible to physical activity and smoking in this aspect.
The relationship between asthma and high BMI has been reported in several previous studies [
]. We found that subjects with asthma had a higher prevalence of diabetes compared to subjects without asthma, an association that was still evident when adjusted for BMI and the level of physical activity. This result is in accordance with a small study on obese children that showed that the children with asthma had a higher prevalence of insulin resistance than non-asthmatic children [
The study benefits from the large sample size and the use of data from a random general population sample. The physical activity and respiratory questions have been used in previous studies [
]. The study also has several limitations such as having a cross-sectional study design and therefore being unable to establish causality. The information on physical activity is self-reported and may therefore not reveal the real levels of physical activity, which may be overestimated [
]. However, it is unlikely that the degree of overestimation should differ between subjects with and without asthma. The study did not include questions on physical activity during work. The questionnaire also lacks questions on what type of exercise the subjects performed. As in many similar studies [
We conclude that almost 60% of the participants in this large unselected population of Swedish adolescents and adults did not meet the recommended health enhancing level of physical activity. There was no difference between subjects with and without asthma in this respect, indicating that having asthma does not have to be an obstacle to meeting the recommended levels of physical activity. Health care professionals should, however, be aware of the increased prevalence of asthma in vigorously physically active subjects.
Authors contributions
CaJ and EM wrote the manuscript, ChJ and ME analysed the data. LE and RM collected data. RM, ChJ, and KL supervised the study and contributed to the design of data analyses. AB, LE, KF, BJ, KL and AM contributed to data analysis. All co-authors contributed to drafting the manuscript or revised it critically.
Conflict of interest
None of the authors have a declared conflict of interest.
Acknowledgements
The study was carried out as part of the GA2LEN survey and follow-up and was supported by the EU FP6 project GA2LEN (EU contract nr. FOOD-CT-2004-506378), the Centre for Allergy Research at the Karolinska Institutet, the Swedish Heart Lung Foundation, the Swedish Heart and Lung Association, and the Swedish Asthma and Allergy Association.
References
Garber C.E.
Blissmer B.
Deschenes M.R.
Franklin B.A.
Lamonte M.J.
Lee I.M.
American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise.
The association between BMI, vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema in children and adolescents: ISAAC phase three.
Exercise-induced asthma, respiratory and allergic disorders in elite athletes: epidemiology, mechanisms and diagnosis: part I of the report from the Joint Task Force of the European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA2LEN.
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