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Physical exercise is known to be beneficial to the general control of asthma. However, the benefits specifically on asthma at night has not been well studied.
Asthma is a chronic disorder of the lungs that affects millions of people of all ages. Asthma is characterized by inflammation that causes airway obstruction and hyper-responsiveness. It is associated with flare-ups of wheezing, chest tightness, coughing, and difficulty breathing. Asthma at night is common in those who suffer from asthma and can disrupt sleep, cause tiredness during the day, impair cognition, and negatively affect the quality of life.
Evidence has suggested that nighttime asthma is different from asthma during the day, however, its mechanism is not completely understood since patients with optimal medical treatment can still experience asthma at night. Although physical exercise is beneficial to general asthma control, its specific effects on asthma at night have not been studied. To explore this further, researchers from Canada performed a review of studies to determine the effects of physical exercise on asthma at night and published their findings in PLOS ONE.
In their systematic review, the researchers found studies that had results on asthma symptoms at night before and after a physical activity intervention. Their main inclusion criteria were:
- Trials with asthma patients
- Trials with a physical activity intervention of at least 20 minutes per day, at least twice weekly for at least four weeks
- Trials evaluating nighttime asthma symptoms or sleep quality affected by asthma before and after physical activity
They included 11 studies in the review. Five were studies done in children and six were done in adults (over the age of 18). The included studies used different assessment questionnaires to evaluate sleep quality and the symptoms of asthma at night. Some of the questionnaires used included the Asthma Control Questionnaire (ACQ), Asthma Quality of Life Questionnaire (AQLQ), and the Paediatric Asthma Quality of Life Questionnaire.
Exercise reduced nighttime asthma prevalence and symptoms
The researchers found that physical activity in children twice weekly for at least six weeks reduced the prevalence of nighttime asthma symptoms. Children who did supervised aerobic physical exercise twice weekly for eight weeks had improvements in their asthma symptoms at night.
Non-obese asthmatic adults saw a reduced prevalence and frequency of nighttime asthma, and better quality of sleep when supervised physical exercise was done for at least 12 weeks. Similar results of improved asthma at night and sleep quality were seen in obese asthmatic adults when supervised physical exercise was done for at least 10 weeks.
In both adults and children, the studies showed that physical activity improved airway inflammation, which can help with overall asthma control during the day and at night.
Only a small number of studies were included in the review
This systematic review is limited by several factors. There were a small number of studies included for review, and the studies themselves had a small number of participants. The variations in physical activity intervention routines and duration, and the methods of evaluating outcomes also limited the findings. Medication usage was not reported in all the studies, which could have affected the results since medications can affect asthma control and the ability to exercise.
Mechanism of how exercise reduces asthma symptoms is currently unknown
Regardless of the study limitations, the researchers conclude that their findings demonstrate the benefits of physical activity on nighttime asthma by reducing the prevalence and frequency of symptoms. The underlying mechanism for how physical activity improves asthma at night remains unknown and would require further research. Future studies may lead to recommendations on physical activity routines as an alternative or complementary treatment in asthma patients.
Written by Maggie Leung, PharmD
Reference: Francisco, C. D., Bhatawadekar, S. A., Babineau, J., Reid, W. D., &Yadollahi, A. (2018). Effects of physical exercise training on nocturnal symptoms in asthma: Systematic review. Plos One,13(10).doi:10.1371/journal.pone.0204953