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As a group, children with a chronic disease or disability are less active than their healthy peers. There are many reasons for suboptimal physical activity, including biological, psychological and social factors. Furthermore, the lack of specific guidelines for ‘safe’ physical activity participation poses a barrier to increasing activity. Physical activity provides significant general health benefits and may improve disease outcomes. Each child with a chronic illness should be evaluated by an experienced physician for activity counselling and for identifing any contraindications to participation. The present statement reviews the benefits and risks of participation in sport and exercise for children with juvenile arthritis, hemophilia, asthma and cystic fibrosis. Guidelines for participation are included.
En tant que groupe, les enfants ayant une maladie ou une incapacité chronique sont moins actifs que leurs camarades en bonne santé. De nombreuses raisons expliquent une activité physique sous-optimale, y compris des facteurs biologiques, psychologiques et sociaux. De plus, l’absence de lignes directrices précises sur la participation à des activités physiques « sécuritaires » représente un obstacle pour accroître l’activité. L’activité physique procure d’importants bienfaits généraux pour la santé et peut améliorer l’issue des maladies. Un médecin d’expérience devrait évaluer chaque enfant ayant une maladie chronique pour lui donner des conseils sur les activités physiques qu’il peut pratiquer et pour en déterminer les contre-indications. Le présent document de principes porte sur les bienfaits et les risques de la participation au sport et à l’exercice pour les enfants ayant l’arthrite juvénile, l’hémophilie, l’asthme ou la fibrose kystique. Les lignes directrices régissant leur participation sont exposées.
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Sports medicine pioneers, such as Oded Bar-Or, recognized the need to study exercise risks and benefits in children with chronic disease (1). The Canadian Paediatric Society and the Canadian Academy of Sport Medicine endorse the present statement regarding issues in children with juvenile idiopathic arthritis (JIA), hemophilia, asthma and cystic fibrosis (CF).
JIA (previously known as juvenile rheumatoid arthritis) has a prevalence of one in 1000 children (2). There are seven subtypes of JIA, likely representing different pathogenic mechanisms (3). Chronic arthritis is defined by the presence of joint swelling, or by two or more of the following: joint pain, warmth and limited range of motion for at least six weeks. Constitutional signs or symptoms include anorexia, weight loss, growth failure and fatigue. Extra-articular manifestations include ocular, cardiac, pulmonary and hematopoietic involvement. JIA persists into adulthood in up to 55% of patients, and may have a major impact on physical or psychosocial function. Children with JIA have reduced vigorous physical activity levels, sports participation and decreased fitness (4).
Muscle atrophy, weakness and anemia contribute to reduced fitness, but deconditioning from reduced physical activity is likely the greatest cause. Reduced participation because of disease symptom severity, treatment-related side effects or worries that exercise may aggravate disease is problematic.
Physical activity should be encouraged in all children. The psychosocial benefits of group participation cannot be understated. Exercise can have positive biological effects by reducing loss of proteoglycans and cartilage damage, and optimizing bone mineral density. Active children have lower obesity risks, which can worsen joint load.
Research suggests that children with JIA can participate in aquatic or land-based weight-bearing exercise programs without disease exacerbation (4). Aquatic exercise encourages range of motion, strength and fitness, with less stress on joints. Weight-bearing activity helps promote bone health.
Most published studies are small, not randomized, have great variation in study design and use different exercise modalities. The exercise intensity, frequency and duration also vary. Despite these differences, the results are generally consistent, suggesting that an exercise program (a minimum of six weeks) improves aerobic fitness; allows better muscle strength and function; decreases disease activity; improves self-efficacy, energy level and quality of life; and reduces pain and medication use, with no clear effect on function during activities (4–8). Importantly, sports participation does not appear to exacerbate disease (9). The 2002 Exercise and Physical Activity Conference Arthritis Working Group guidelines recommend moderate fitness and strengthening exercises for children with JIA (8).
Conventionally, affected children were advised to limit strain on arthritic joints for fear it may aggravate joint pain or swelling, increasing risk of injury. Muscle atrophy surrounding active joints and periarticular osteopenia may increase the risk of fracture. The effect of tissue loading during exercise on joint surfaces and growth plates in children with arthritis is unknown, and requires further study.
Young children with JIA may have gross motor delays, affecting sport readiness. Children with cervical spine arthritis are at greater risk of spinal cord injury (especially during contact sports), and those with temporomandibular joint disease may sustain dental injury. Complications of JIA, such as to uveitis and its sequelae (visual impairment), may increase the risk of eye injury. Myocarditis and pericarditis in systemic arthritis, and aortic valve insufficiency or aortic root anomalies in HLA-B27-associated arthritis, may increase the risk of cardiovascular complications with exercise (10).
Children with long-standing JIA may have difficulties with endurance sports. Greater submaximal energy expenditures are reported, suggesting increased metabolic demands for routine physical activity (11). A meta-analysis of five JIA studies (12) found that aerobic fitness in children with JIA was 22% lower than their healthy peers. Most research suggests aerobic fitness is not related to disease severity or activity but rather to disease duration (12–14).
Hemophilia is an X-linked recessive inherited bleeding disorder caused by the absence, deficiency or dysfunction of plasma coagulation factor VIII or IX. Hemophilia has an incidence of one per 5000 newborns. Clinical phenotype and risk of hemorrhage varies from mild to severe, and is related to functional plasma factor levels (15).
Children with severe hemophilia (less than 1% to 2% of normal factor levels) have spontaneous bleeding even without trauma. Joint or muscle hemorrhage, easy bruising and prolonged bleeding after trauma are common, and severe bleeding (intracranial, vital organs, airway) may occur. Repeated joint hemorrhage causes synovitis, leading to joint degeneration and arthropathy. Hemophilia is characterized by joint contractures, limited range of motion and chronic pain. The knees, ankles and elbows are most commonly affected. Prophylactic treatment with the deficient factor reduces spontaneous bleeding and the risk for hemophilic arthropathy.
Regularly active children at hemophilia camps have fewer bleeding episodes than their sedentary peers (16). Greater muscle strength around affected joints may help to protect joints from hemarthrosis, increase joint stability and reduce injury risk (17). Prophylactic physical therapy improving periarticular muscle strength was demonstrated to reduce the frequency of hemorrhage (17,18). Proprioceptive training may decrease joint damage and improve athletic performance (19). Weight-bearing exercise can improve bone health in children with severe hemophilia who have reduced bone mineral density (20). Aerobic exercise may have a beneficial effect on coagulation. Vigorous exercise increases factor VIII levels transiently in healthy individuals, and submaximal exercise can modify coagulation parameters in those with mild to moderate hemophilia (21).
Fitness, anaerobic power and muscle strength are lower in children with hemophilia (19,21). Affected children may restrict activity due to parental concern, musculoskeletal pain or deconditioning. Although hemophilia itself does not negatively affect fitness or athletic performance, chronic hemophilic arthropathy may lead to impaired neuromuscular function, diminished muscle strength and endurance. Participation in collision or contact sports can result in a life-threatening bleeding event. The actual risk of muscular, articular and intracranial hemorrhage depends on the individual child’s hemorrhagic tendency, history of bleeds, prophylactic treatment and sport participation.
Asthma is the most common paediatric chronic disease, with more than 300,000 Canadian children affected (22). Higher rates appear to be associated with poor socioeconomic status, obesity and low physical activity levels. Asthma is a chronic inflammatory disorder of the airways, characterized by airway hyper-responsiveness and reversible airflow limitation. Typical presenting symptoms include shortness of breath, cough and wheezing. Asthma is associated with greater bronchial hyper-reactivity to viral infections, cigarette smoke, inhaled allergens, emotional stress, environmental factors and exercise. Exercise and emotions trigger bronchospasm but minimal inflammation. Rarely is exercising the only trigger, making ‘exercise-induced bronchospasm’ (EIB) better terminology.
Almost 90% of asthmatic patients and 40% of individuals with allergic rhinitis experience EIB. In children, EIB may be the first presentation of asthma. Overall prevalence in high school, college and Olympic athletes is 12% (23), although this is probably underestimated (24). Exercise-related dyspnea is often mistakenly diagnosed as EIB; however, bronchial hyper-responsiveness is not associated with exercise-related dyspnea (25).
In patients with EIB, bronchoconstriction typically occurs after 8 min to 15 min of physical activity and resolves within 60 min. Running and other land-based cardiovascular exercises (rarely swimming) are common triggers. One popular hypothesis regarding EIB pathogenesis is the evaporation of water lining the airways secondary to higher ventilatory rates during and after exercise (26). Alternatively, cold, dry air may cause an osmotic gradient across mast cells, resulting in mediator release. Fifty per cent of asthmatic children without EIB symptoms can be diagnosed using an exercise challenge pulmonary function test (PFT) (26,27). A drop of 10% to 15% in forced expiratory volume in 1 s (FEV1) from baseline, following vigorous exercise for approximately 6 min to 8 min, is diagnostic of EIB. The sensitivity and specificity of exercise PFT in children are up to 63% and 94%, respectively (28). Eucapnic voluntary hyperventilation testing is the preferred challenge test for EIB in athletes, because pharmacological challenge tests have low sensitivity in this setting (29).
Asthma management should include identification of disease severity and known triggers, and the creation of a written action plan. Those with persistent symptoms and/or abnormal baseline PFT results require ongoing anti-inflammatory treatment with inhaled corticosteroids and/or leukotriene antagonists. Beta-2 agonists are used as rescue medication or before exercise to prevent EIB. Children with mild intermittent disease triggered by exercise may benefit from nonpharmacological interventions (nose breathing and warm-up exercises) as well as pre-event inhaled beta-2 agonists. Those in prolonged activities may benefit from a long-acting beta-2 agonist (formoterol) with rapid onset. Athletes should take these agents 15 min to 30 min before exercise (30). Those who compete nationally and internationally require a therapeutic use exemption form, with documentation of asthma or EIB to use certain medications (27,30). Athletes are strongly advised to consult the Canadian Centre for Ethics in Sport (www.cces.ca), the World Anti-Doping Agency (www.wada-ama.org) and their international sport federation to determine the current required documentation.
Children with asthma exhibit similar activity levels as their unaffected peers (31). Both have similar self-perceptions or physical self-concept. Disease severity and parental concerns present possible barriers.
Physical and/or psychosocial benefits of exercise are evident. Bronchial hyper-responsiveness increases with decreasing hours of exercise per week (32). Swimming can increase aerobic fitness and decrease asthma morbidity (33). Exercise training can improve aerobic capacity; however, PFTs do not change significantly (34).
Exercise may decrease EIB severity by increasing the threshold for triggering bronchospasm. Approximately 50% of affected individuals can experience this ‘refractory period’ up to 4 h after initial exercise, resulting in decreased bronchoconstriction during subsequent exercise (35). In some cases, athletes can warm-up with exercise 45 min to 60 min before scheduled activities to reduce their subsequent asthmatic symptoms, and to improve exercise capacity and quality of life.
High-intensity exercise can trigger EIB by increasing minute ventilation and respiratory heat/water losses, leading to a greater drop in FEV1 (36). Permanent bronchial changes may occur in endurance athletes, who seem to have higher rates of bronchial hyper-responsiveness (37). Certain sports expose individuals to dry, cool air (38), environmental allergens and pollutants, which may trigger flares. Athletes in running and winter sports have more reported symptoms (39). Breathing humid air during swimming may be protective (40), but potential risks from exaggerated parasympathetic tone (‘diving reflex’) and chlorine-related airway irritation that triggers bronchoconstriction may occur (33). It is controversial whether asthma patients are at higher risk of scuba diving injury. They should have normal spirometry (especially residual volume) at rest and in response to exercise before being certified to dive.
Asthma-related deaths of individuals younger than 20 years of age, although rare, have been reported in both competitive and recreational sports (eg, basketball and track) (41).
CF is the most common lethal autosomal recessive disease in Canada, affecting one in 3600 Caucasian live births (42). Men and women are equally affected, although men have a longer life expectancy (43). CF is caused by mutations in the CF transmembrane conductance regulator protein, a complex chloride channel located in all exocrine tissues (44). Abnormal chloride transport leads to viscous secretions in the pulmonary, gastrointestinal, endocrine and reproductive systems, and greater salt loss in sweat. Diagnostic sweat chloride testing remains the gold standard. Sixty per cent are diagnosed by one year of age and 90% by 10 years of age (42). Rapid diagnosis using genetic and newborn sweat chloride testing show promise (42). Pulmonary disease is the most common cause of morbidity and mortality, but early diagnosis and improvements in therapy have increased mean survival rates to 33 years of age (45).
Physicians emphasizing exercise, in addition to routine CF treatment, help CF children develop positive attitudes toward exercise. Some may become triathletes or marathon runners (46). Disease severity is variable among children with CF, affecting individual exercise tolerance.
CF children with high aerobic fitness experience slower deterioration in lung function and greater survival rates (47–49). Training programs can improve exercise tolerance, particularly in those with low fitness levels (50). Enhanced lung mucous clearance can occur during intense exercise (51). Swimming, walking and jogging can improve strength and endurance of respiratory muscles (52). Strength training may improve fat-free mass, weight gain, muscle strength and FEV1 in affected patients (53).
Children with CF may cough with exercise, causing brief oxygen desaturation. However, there is no evidence that this effect causes significant injury (46,54). Some children cough because of underlying asthma. Major limitations to exercise are degrees of lung disease and subnormal ventilatory capacity. These limitations may be a consequence of bronchial narrowing (edema), bronchospasm, mucous plugging and reduced alveolar ventilation (55). Lung parenchyma destruction results in decreased diffusing capacity leading to oxygen desaturation, CO2 retention and cyanosis (55,56). Desaturation of arterial oxygen from significant ventilation-perfusion mismatching, intrapulmonary right-to-left shunting or cor pulmonale with congestive right heart failure (57) occurs. Cardiac dysfunction is noted in patients with advanced CF (resting FEV1 lower than 50% predicted) who have lower stroke volumes or cardiac output, and in mild CF patients during submaximal exercise testing. Maximal heart rate during testing is often lower than in healthy peers (58). All CF patients can develop localized air trapping, increasing the risk of air embolus or pneumothorax during scuba diving.
Resting energy expenditure is 5% to 25% higher in CF youth (59–62), limiting exercise tolerance. Chronic malnutrition may cause lower muscle mass or strength (respiratory or skeletal), impairing sport performance (63). These working muscles have poor oxidative efficiency, contributing to early fatigability (63).
Affected children have greater sweat-related salt losses, making exercise in hot or humid environments challenging (64). Prolonged exercise (1.5 h to 3 h) can lead to hyponatremic dehydration (65). Prevention by ingesting flavoured sodium chloride-containing drinks (50 mmol/L) above thirst levels is recommended (65). CF-related diabetes mellitus makes hypoglycemia and dehydration (polyuria) potential concerns with prolonged exercise; hence, additional carbohydrate supplementation is required (66). Multilobular biliary cirrhosis and portal hypertension are frequent complications of CF liver disease, leading to esophageal varices and splenomegaly. Those with splenomegaly or liver dysfunction have a higher risk of organ damage during contact or collision sports.
Physical activity and sport are primary means of exercise and social activity in childhood. Through participation, children can develop fitness, social skills and relationships. Despite chronic disease, each individual has a unique exercise tolerance and physical capacity.
This position statement was jointly prepared by members of the Canadian Paediatric Society’s Healthy Active Living and Sport Medicine Committee, and the Canadian Academy of Sport Medicine’s Paediatric Sport and Exercise Medicine Committee. It was also reviewed by the following groups of the Canadian Paediatric Society: Community Paediatrics Committee, Psychosocial Paediatrics Committee, Respiratory Health Section and Paediatric Rheumatology Section.
CANADIAN PAEDIATRIC SOCIETY – Healthy Active Living Committee
Members: Drs Claire LeBlanc, Edmonton, Alberta (Chair); Tracy Bridger, St John’s, Newfoundland; Kristin Houghton, Vancouver, British Columbia; Stan Lipnowski, Winnipeg, Manitoba; Peter Nieman, Calgary, Alberta; John Philpott, Toronto, Ontario; Tom Warshawski, Kamloops, British Columbia
Liaison: Dr Laura Purcell, London, Ontario (Canadian Paediatric Society, Paediatric Sport and Exercise Medicine Section)
CANADIAN ACADEMY OF SPORT MEDICINE – Paediatric Sport and Exercise Medicine Committee
Members of Working Group: John Philpott (Chair), Laura Purcell (Past-Chair), Tim Rindlisbacher (Secretary), Merrilee Zetaruk, Kristin Houghton, Anthony Luke, Claire LeBlanc, Devin Peterson, Elaine Joughin, Laura Cruz
Principal authors: J Philpott, K Houghton, A Luke; Canadian Paediatric Society, Healthy Active Living and Sports Medicine Committee and the Canadian Academy of Sport Medicine, Pediatric Sport and Exercise Medicine Committee
The recommendations in this statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. All Canadian Paediatric Society position statements are reviewed, revised or retired as needed on a regular basis. For the most current version, please consult the “Position Statements” section of the CPS Web site (www.cps.ca/english/publications/statementsindex.htm).