Comparison of morning and afternoon exercise training for asthmatic children

Brazilian Journal of Medical and Biological Research (2006) 39: 71-78 Exercise training for asthmatic children ISSN 0100-879X 71 Comparison of morning and afternoon exercise training for asthmatic children C.S. Silva1, L.A.G.M.M. Torres2, A. Rahal3, J. Terra Filho1 and E.O. Vianna1 1Divisão de Pneumologia, Departamento de Clínica Médica, 2Departamento de Pediatria, Faculdade de Medicina de Ribeirão Preto, 3Centro de Educação Física e Recreação, Universidade de São Paulo, Ribeirão Preto, SP, Brasil Abstract Correspondence E.O. Vianna Divisão de Pneumologia Departamento de Clínica Médica FMRP, USP Av. Bandeirantes, 3900 14048-900 Ribeirão Preto, SP Brasil Fax: +55-16-3633-6695 E-mail: Research supported by FAPESP. Received April 8, 2005 Accepted September 19, 2005 Fitness improvement was used to compare morning with afternoon exercise periods for asthmatic children. Children with persistent moderate asthma (according to GINA criteria), 8 to 11 years old, were divided into 3 groups: morning training group (N = 23), afternoon training group (N = 23), and non-training group (N = 23). The program was based on twice a week 90-min sessions for 4 months. We measured the 9-min running distance, resting heart rate and abdominal muscle strength (sit-up number) before and after the training. All children took budesonide, 400 µg/day, and an on demand inhaled ßagonist. The distance covered in 9 min increased (mean ± SEM) from 1344 ± 30 m by 248 ± 30 m for the morning group, from 1327 ± 30 m by 162 ± 20 m for the afternoon group, and from 1310 ± 20 m by 2 ± 20 m for the control group (P < 0.05 for the comparison of morning and afternoon groups with the control group by ANOVA and P > 0.05 for morning with afternoon comparison). The reduction of resting heart rate from 83 ± 1, 85 ± 2 and 86 ± 1 bpm was 5.1 ± 0.8 bpm in the morning group, 4.4 ± 0.8 bpm in the afternoon group, and -0.2 ± 0.7 bpm in the control group (P > 0.05 for morning with afternoon comparison and P < 0.05 versus control). The number of situps in the morning, afternoon and control groups increased from 22.0 ± 1.7, 24.3 ± 1.4 and 23 ± 1.1 sit-ups by 9.8 ± 0.9, 7.7 ± 1.4, and 1.9 ± 0.7 sit-ups, respectively (P > 0.05 for morning with afternoon comparison and P < 0.05 versus control). No statistically significant differences were detected between the morning and afternoon groups in terms of physical training of asthmatic children. Introduction Circadian rhythms or diurnal variations in responses to exercise have been studied in recent years (1-5). Results have depended on a variety of factors in the experimental design, such as kind and intensity of exer- Key words • Asthma • Children • Chronotherapy • Exercise training • Circadian rhythm • Exercise-induced bronchospasm cise, and other parameters. It is clear, however, that there are some differences in response to exercise that depend on the time of day when the activity is performed (5). The importance of exercise for health is well known; however, there are no prescribed guidelines about the relative effects of exerBraz J Med Biol Res 39(1) 2006 72 C.S. Silva et al. cising at different times of day. These may be important for both the safety and efficacy of training programs. More and more, physical exercise is commonly suggested and indicated for children with chronic disease. Asthma patients frequently have poor fitness that can lead to social isolation, further increasing the negative self-concept (6-8). Although regular physical exercise cannot cure asthma, several studies have suggested that physical exercise is an essential component of pulmonary rehabilitation (9). For asthmatic children, physical training increases exercise tolerance, improves fitness, flexibility, muscle strength, decreases use of medication, decreases school absenteeism, and improves self-esteem and confidence (9,10). Different exercise programs have been evaluated mainly regarding duration, frequency and modalities, for example, comparing activities that induce a minimum of exerciseinduced bronchospasm (EIB) (10). At present, it is not known whether time of day influences the effects of a set training regimen for asthmatic sedentary children. Nocturnal worsening of asthma is a recognized and important aspect of the disorder and must be considered in the management of the disease process. For the diurnally active asthmatic patient, a circadian pattern in lung function (for example, FEV1) occurs, the lung function peak occurring at approximately 16:00 h and the nadir at approximately 4:00 h (11,12). Based on the characteristics of asthma, that oscillate according to a circadian rhythm, we hypothesized that time of day may influence the effects of physical exercise training. Therefore, we designed this study to compare morning with afternoon exercise by asthmatic children in an exercise training program. Subjects and Methods Subjects Sixty-nine children with persistent modBraz J Med Biol Res 39(1) 2006 erate asthma, 8-11 years of age, were enrolled in this prospective trial. The children were randomly assigned to 3 groups of 23 subjects each: morning training group (morning), afternoon training group (afternoon), and non-training group (control). Although the children were physically active, none was following a regular exercise training program. The children were in a stable phase of the disease, with no exacerbation during the 15 days before the beginning of the tests. The inclusion criteria were physiciandiagnosed asthma classified according to the Global Initiative for Asthma (13) and clinical stability in the 6 weeks preceding the tests. Exclusion criteria were use of oral steroids in the previous 8 weeks, physical disability, and other pulmonary or systemic disease. All children included in the study were taking budesonide, 400 µg/day, and an inhaled ß-agonist (albuterol) as needed for at least 1 month before evaluation for the study. None were taking oral steroids, theophylline, a long-acting ß-agonist, a leukotriene modifier, or cromone. All medication was offered and the prescription was not modified during the study period. Medical follow-up was performed by the same staff physician. The study was approved by the Institutional Ethics Committee of the University of São Paulo Medical School at Ribeirão Preto. Written informed consent was obtained from the children and their parents. Patient transportation (home to study site, round trip) was provided by the investigators. Protocol A clinical history was obtained from all subjects, followed by physical examination, anthropometry and FEV1 measurement. On a different day, patients performed an exercise challenge test after measurement of resting heart rate. One day before the initial sessions of exercise training, number of sit- 73 Exercise training for asthmatic children ups in 60 s and 9-min running distance were evaluated for the three groups. The subjects of all three groups were evaluated before and after a 4- (...truncated)