The Effect of Eight Weeks of Moderate Intensity Aerobic Exercise on FVC and FEV1 in Mature and Immature Girls with Asthma in Humid Environment

Asthma is a common chronic airway disease that has a dramatic effect on the process of life, group activity and socio-psychological functioning and even the economic progress of patients. There are currently 300 million asthma patients worldwide and it is predicted that by 2025, 100 million asthma patients will be added to the world population (1). Exacerbation of the symptoms of the disease affects the quality of life as well as the cost of treatment. Complications of chronic obstructive pulmonary disease include respiratory failure, pneumonia or other respiratory infections, right heart failure (pulmonary heart), arrhythmias, and depression. Asthma control is determined by the frequency of symptoms during the day, activity limitations, nocturnal symptoms, the need for essential medications, and lung function (4).
Studies show that unhealthy lifestyles such as inactivity and obesity are associated with negative health consequences in asthma patients, including poor asthma control (5). Among the measures taken to relieve symptoms and improve the functional status of patients with these diseases are pulmonary rehabilitation and breathing exercise and exercise programs that are part of it are used to improve functional status (6). Numerous clinical studies have shown that exercise, as part of a pulmonary rehabilitation program, improves asthma control and overall physical fitness in people with asthma and reduces hospitalization rates (7). Resistance training and strengthening the muscles of inhaling and exhaling are among the techniques that increase respiratory function in respiratory patients (8).
Regarding the beneficial effects of exercise in asthma patients, many studies have shown that physical activity and regular exercise play a beneficial role in reducing respiratory tract inflammation, shortness of breath and improving or maintaining pulmonary capacity such as Forced expiratory volume in the first second (FEV1) and has a Forced vital capacity (FVC) throughout the life of asthma patients (9-12). However, some studies have shown that during the period of sports interventions, patients had emergency conditions and exacerbation of asthma (13,14). Turner et al. Found that some patients had exacerbated asthma during exercise (14).
Asthma in adolescents and children can have detrimental effects on their mood and social activities. Over the past decades, a 100% increase in childhood obesity has been implicated in the prevalence of asthma because it affects the physiopathology and mechanics of the lungs. Because maintaining asthma control through medication is at a difficult level, it seems that getting help from lifestyle changes, such as including regular physical activity in the asthma patients' lifestyle, can help control asthma (8). Recent evidence in systematic studies has led to the support of aerobic exercise as an aid to the treatment of asthma, and despite standard treatment, its supply to asthma patients has become essential. However, the role of regular exercise, especially breathing exercises, in very limited asthma control has been investigated. Therefore, the present study investigated the effect of eight weeks of moderate intensity aerobic exercise on FVC and  FEV1 in mature and immature girls with asthma in humid environment.

In this semi- experimental trial, 60 girls students with asthma (30 mature and 30 immature girls; with average age of 8-18 years) from Rasht city were randomly selected and randomly divided into two groups include exercise and control. The aerobic exercise program was performed with intensity of  45-75% of maximum heart rate, 3 sessions per week for 8 weeks. Spirometry test was performed to determine pulmonary function before and after the training protocol. Data were analyzed using 2-factor analysis of covariance (ANCOVA) test at the p≤0.05. 

Aerobic exercise led to significant increase in FEV1 in girls with asthma (P= 0.000). There was no significant difference between the effect of aerobic exercise on FEV1 in mature and immature girls with asthma. Aerobic exercise led to significant increase in FVC in girls with asthma (P= 0.000). There was no significant difference between the mean FVC of mature and immature girls with asthma.

The results of the present study showed that after the intervention period, FEV1 levels  significantly increases in girls with asthma. Also, the mean FEV1 of adult girls was significantly higher than immature girls with asthma. The results showed that increasing FEV1 had beneficial effect on improving asthma control. The results of the present study are consistent with some previous findings (20-22). Increasing or improving pulmonary function with exercise seems to be related to reducing airway resistance, increasing airway diameter, as well as strengthening the respiratory muscles and the elastic properties of the lungs and chest. On the other hand, the effects of adrenaline and cortisol may be effective. Increased activity of the adrenaline system during exercise reduces the reversibility of the lungs and dilation of the pulmonary arteries. Also, the increase in plasma levels of cortisol as a bronchodilator is a very strong and strong production of surfactant in the lungs (19). Asthma is classified clinically according to the frequency of symptoms, expiratory volume with pressure per second (FEV1) and maximum expiratory flow rate (23). Strengthening the respiratory muscles, increasing the effective tail force due to strengthening the elasticity of the main and auxiliary intercostal muscle fibers, reducing obesity and thus reducing the pressure caused by the accumulation of fat around the chest have been reported as mechanisms of effect of exercise in improving lung function (25). In the present study, moderate-intensity aerobic exercise increased FVC in girls with asthma. The findings of our study also showed that aerobic exercise along with resistance exercise can be associated with an increase in  spirometry indices FEV1 and FVC. These results are consistent with the results of previous research (20-22). The value of the FVC index depends on the elasticity of the lungs, the authority of the airways. Studies have shown that the elasticity of the lungs, the position of the ducts between the alveolar region and the location of the stenosis and dilatation of the airway wall are effective physiological mechanisms in determining airflow at this stage. The increase in FVC appears to be due to aerobic exercise due to increased lung volume and elastic reversal of the lungs (11). There were some limitations in the present study; One of the limitations of the present study is the lack of measurement of lung function following ventilation. To determine whether the adjustments we observed are the result of exercise or increased ventilation, future studies should examine the effects of over-ventilation on changes in respiratory muscle strength and respiratory volume. Also, more research is needed to understand the effects of long-term aerobic exercise on respiratory volume. The results of this study showed that regular exercise with increased activity tolerance can facilitate the transfer of oxygen to body tissues. As a result, eight weeks of moderate aerobic exercise can cause a positive and favorable change in FEV1 and FVC indices in mature and immature girls with asthma.