Mini-symposium: The Clinical Applications of Exercise Testing in ChildrenExercise Testing in Children with Lung Diseases
Introduction
Exercise is a complex activity which requires the integrative involvement of multiple organ systems - the pulmonary, cardiovascular, haematopoietic, musculoskeletal and neuropsychological systems.1 Exercise testing is an important diagnostic tool in the assessment of the cardiorespiratory status of the child. By placing the pulmonary system under the stress of exercise, subtle functional deficits in the lung may be identified that were not apparent during conventional static pulmonary function testing. Exercise testing is a dynamic assessment of pulmonary function and its utility in detecting early functional deficits due to early lung disease is gaining popularity. Exercise testing can not only help ascertain if exercise capacity is reduced but also define the aetiology of the reduced exercise capacity.
The importance of habitual activity and exercise in both healthy children and children with chronic diseases has been well documented in the literature. A systematic review by Strong et al.3 concluded that there was good evidence for the beneficial effects of habitual activity on musculoskeletal health, cardiovascular health, lipid and lipoprotein levels, self concept and academic performance in children.2 Strong et al.3 also demonstrated evidence for the beneficial effects of habitual activity on adiposity in overweight youth, blood pressure in mildly hypertensive adolescents, and in children with anxiety and depression.2
Children with lung diseases may theoretically have impaired habitual activity because of pulmonary limitation. Unless the pulmonary disease is severe, reduced habitual activity is unlikely to be due to respiratory limitation.3 Other co-existing factors such chronic deconditioning may be significant contributors to impaired habitual activity. Exercise limitation in these children may also be self-imposed or imposed upon them by care-givers because of misperceptions of physical fragility.4 Gender differences in habitual activity have been noted in children with chronic suppurative lung diseases such as cystic fibrosis.5, 6 The aetiology of these gender differences is unclear. Regardless of the cause, regular exercise improves the sense of wellbeing of children and may reduce the rate of decline in lung function in children with cystic fibrosis.6 Physical inactivity is also a risk factor for obesity,2 a condition associated with a myriad of co-morbidities, including insulin resistance, dyslipidaemia, hypertension and sleep disordered breathing.7 Obesity and its co-morbidities can also further contribute to exercise limitation in these children.
In summary, children with respiratory disease may have reduced habitual activity either due to primary respiratory limitation or secondary causes. A negative feedback loop may be created where reduced habitual activity leads to deconditioning, prompting a further reduction in exercise capacity. This will impact on the child's general health and well being, as well as self esteem. Formal exercise tests will help to determine if the aetiology of reduced exercise capacity in children with underlying respiratory disease is due to cardio-respiratory limitation or deconditioning.
Section snippets
Role of exercise testing in children with lung disease
While spirometry and other pulmonary function tests have traditionally been useful in the diagnosis and guidance of management for children with lung disease, these tests measure only static or resting lung function indices and do not reliably predict functional and exercise capacity.1 Exercise testing provides a more accurate functional evaluation and serves as a useful adjunct in the management of children with lung diseases.
Children with lung diseases may have exercise testing for any of the
Physiological responses to exercise
A discussion of exercise testing in children requires a basic understanding of exercise physiology. For a detailed description of exercise physiology we refer the readers to the work of Wasserman et al.9 as it is beyond the scope of this review (Table 2, Table 3, Table 4).
During exercise, patients with mild lung disease achieve optimal alveolar ventilation by increasing tidal volume.10 However, as the severity of lung disease progresses and in children with restrictive lung disease (either
Modalities, measurements and protocols in exercise testing for lung diseases
Exercise testing in children can be done informally as a field test or formally as a cardiopulmonary exercise test (CPET) in a laboratory on a treadmill or cycle ergometer with metabolic measurements using breath by breath exhaled gas analysis.
The main advantage of the formal test is that it measures airflow, peak oxygen consumption (VO2), carbon dioxide production (VCO2), and heart rate during exercise. Together with the measured or estimated work rate (WR) applied during the exercise test,
Asthma & Exercise induced bronchoconstriction
Exercise induced bronchoconstriction is the transient airway narrowing brought on by exercise or physical activity.28, 29 In most cases, EIB reflects airway inflammation and bronchial hyper-reactivity from an underlying respiratory disease such as asthma. In the presence of symptoms or known diagnosis of asthma, the term “exercise induced asthma” is often used interchangeably with EIB.30 However, EIB is not limited to those with asthma, and can also be present in elite athletes in the range of
Cystic fibrosis lung disease
Cystic fibrosis is a disease affecting multiple organ systems, with the greatest morbidity and mortality arising from the respiratory component of the disease. Lung disease in CF is characterised by viscid mucous production leading to bronchiolar obstruction and infection, and progressive deterioration in pulmonary function.44
The role of exercise in maintaining lung function in children with CF has been studied in detail. Most studies are of short term duration and last less than 3 months.
Bronchopulmonary dysplasia
Bronchopulmonary dysplasia (BPD) was well described in 1967 in prematurely born infants with severe respiratory distress syndrome (RDS) who developed a form of chronic lung disease after receiving positive pressure mechanical ventilation and oxygen supplementation.60 With the use of antenatal steroids, surfactant replacement and gentler mechanical ventilation strategies over the past 3 decades, the “classic” form of BPD with markedly hyperinflated cystic radiographic appearance of the lung is
Exercise testing as an outcome measure
Exercise testing is an important tool in assessing the response to a given intervention, and as an outcome measure in clinical trials.72 The intervention may be a therapy for exercise induced asthma or weight control or treatment of arthritis.73, 74
Conclusion
Exercise testing plays an important role in children with respiratory diseases. Together with resting pulmonary function tests, exercise tests help us understand how specific respiratory diseases affect exercise capacity in children. This knowledge can be applied in the optimal management of the diseases in terms of treatment, assessment of response to treatment and prognosis.
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Cited by (18)
Exercise testing for young athletes
2024, Paediatric Respiratory ReviewsAssociations between obesity, asthma and physical activity in children and adolescents
2020, Apunts Sports MedicineCitation Excerpt :A number of studies found lower physical activity levels in children with asthma, whereas others reported no difference in physical activity levels between asthmatic children and healthy peers.80 Furthermore, physical activity and exercise limitation were significantly reduced in 30% of children with asthma.81 The principal factor may be their relative hyperventilation during exercise, which causes dyspnoea and exercise-induced bronchoconstriction (EIB).82
PULMONARY REHABILITATION IN CHILDREN
2017, Revista Medica Clinica Las CondesDiffusion capacity in children: What happens with exercise?
2013, Paediatric Respiratory ReviewsCitation Excerpt :Habitual physical activity can reduce the rate of decline in lung function in patients with CF.4 Until lung function has become moderately to severely reduced (<60% predicted), exercise tolerance in children is not impaired.5 More often poor exercise tolerance is a result of chronic deconditioning or imposed exercise limitation by the individual or caregivers.3 Exercise testing can highlight whether the underlying cause of exercise limitation is due to pulmonary limitation or deconditioning.
Physical activity and exercise in children with chronic health conditions
2013, Journal of Sport and Health ScienceCitation Excerpt :Testing of normal children and those with cardiovascular disease should follow the guidelines of the American Heart Association.109 Exercise challenge testing protocols used to diagnose lung diseases such as asthma are discussed by Teoh et al.80 Regardless of the method used, the test should provide information regarding the function of interest and should be conducted in a manner that provides valid and reliable diagnostic data.110 Evaluation of children with CP is influenced by individual ambulation limitations.7
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