Exercise Testing of Children and Adolescents
To achieve optimal results during exercise evaluations of children, the proper testing environment is critical. The laboratory should be physically attractive to children, containing age-appropriate pictures of interest. The lab should be a minimum of 400 to 600 ft2 (37-56 m2) and have good lighting and ventilation. Room temperature should be maintained between 20° and 22° C (~72° and 76° F) with a relative humidity of less than 60%. Enthusiastic, compassionate, and encouraging staff members who enjoy working with children are essential in successful pediatric exercise testing. With younger children, it is necessary to proceed much more slowly than with adults. Age-appropriate language should be used to describe each piece of equipment and the desired objectives during the test. Pictures of children performing various aspects of the exercise test are also useful in helping younger children to understand what is expected and to feel more at ease. Using this approach, treadmill evaluations have been routinely performed on children as young as 4 years of age.
The use of appropriately sized equipment and protocols is critical. Since children achieve steady state faster than adults, treadmill protocols using 2 or 3 min stages are appropriate. The mode of exercise is also important in determining the results. In children and adolescents, treadmill testing will produce .VO2max values 7% to 10% greater than cycle ergometers, and treadmill running has been found to elicit .VO2max values 6% to 10% higher than treadmill walking. Test protocols should be designed to last between 8 and 12 min.
From a test administration perspective, children consistently rate submaximal exercise lower on RPE charts than do adolescents and adults. Younger children are often intimidated about communicating with unfamiliar adults in new situations. The test administrator must continuously monitor the child by asking frequent questions to assess his or her status as the test progresses. To avoid false positive answers and early test termination, refrain from asking leading questions or describing specific symptoms (e.g., chest or leg pain, dizziness, shortness of breath). Younger, unfit adolescent clients may require strong verbal encouragement to achieve satisfactory intensity levels during exercise evaluation.
Exercise prescriptions for children should take into consideration the attention span of the child as well as the extent to which the parent(s) provide appropriate role models. Prescribed activities should be enjoyable and relatively nonspecific, with increased movement as the initial goal, especially if the child has a long history of physically inactivity.
Benefits of Exercise Testing
The potential benefits of conducting exercise tests in children with various diseases or disabilities include the following:
- Documenting any impairment in cardiac or pulmonary functional capacity
- Detecting and managing exercise-induced asthma
- Detecting myocardial ischemia
- Assessing physical work capacity
- Assessing the results of rehabilitation programs
- Documenting functional changes during the course of a progressive disease
- Providing indications for surgery, therapy, or additional tests
- Assessing cardiac rate and rhythm as well as blood pressure response
- Assessing exercise-related symptoms
- Evaluating the effects of therapy
- Increasing confidence, in the child and parents, in the ability of the child to exercise safely
Risks of Exercise Testing
Although less validated than in adults, exercise testing in children is considered relatively safe and is generally thought to carry a much lower risk than testing in adult clients. The use of side rails and handrails can help reduce the potential risk of falling. Detailed guidelines for conducting pediatric exercise tests are available from the American Heart Association and the American College of Sports Medicine (ACSM).
General Physical Activity Concerns for Children With a Chronic Health Condition or Disability
Special care is taken in working with children, as any child constantly changes during growth and development and each child does so at different rates. When children or adolescents present with a disease or disability, these growth and development concerns may be even more significant due to the effect of the health status on the maturation process. Although physical activity should be expected to provide many of the same benefits to all children, the individual’s health status may impose limitations. A condition or its treatment may retard growth and affect the development of functional systems integral to physical performance, thereby limiting the individual’s ability to participate in activity. Parental apprehension about the child’s involvement in activity must be considered and adequate measures taken to address those concerns. This will require reassurance by the physician, program professionals, and activity leaders. Parents should be allowed to observe (unobtrusively) all sessions and must be fully informed of all details of the child’s participation.
Fitness and health assessments for children and adolescents with chronic diseases or disabilities are essentially the same as for normal children, with the addition of precautions appropriate to the condition. Besides condition-specific clinical evaluations to facilitate appropriate exercise prescription and intervention, assessments of body composition, neuromuscular function, and aerobic and anaerobic fitness should be performed in children with chronic diseases and disabilities. Methodologies and protocols suitable for these children are discussed in detail in numerous sources.
The benefits, risks, and precautions that apply to healthy children are generally the same for those affected by disease or disability. The primary benefit of participation in physical activity for all children is improved quality of life with respect to social, psychological, and physical well-being. For the child affected by disease or disability, the therapeutic consequences of exercise can be significant. Self-esteem, self-efficacy, and self-concept, especially as the child ages, can be greatly enhanced if he or she can have a nearly normal lifestyle of activity. Furthermore, for these children, regular exercise should have the same primary preventive benefits with respect to other diseases, such as coronary artery disease, osteoporosis, hypertension, diabetes, and obesity.
Depending on the particular characteristics of a disease or disability, special consideration must be given to the intensity of an activity, the environmental conditions, and the risk for contact injury. Very-high-intensity efforts can lead to injuries in any child, but those with chronic lung disease such as cystic fibrosis, congenital heart defects, or sickle cell disease have an increased risk of injury and must be considered accordingly. Children are less able than adults to accommodate very high or very low environmental temperatures, and those with a compromised health status may be even less able to adapt to such environmentally stressful conditions. Activities like climbing and diving may not be appropriate for children with certain conditions. Each case should be evaluated on its own merits.
Selected Diseases and Disorders of Children and Youth
As already discussed, all children respond and adapt to exercise somewhat differently than do older youth and adults. Those who are affected by disease or disability may display even greater variation. This section addresses response issues within selected conditions, as well as how the role of physical activity in the growth and development of normal children might be altered by the child’s health status.
Congenital and Acquired Heart Defects
In every 1,000 live births, approximately eight infants have some type of heart defect ranging from mild to very severe. Most children with congenital heart defects (CHD) do not require activity restrictions and can participate in normal physical activity. However, some children with severe or very complex CHD may need to avoid strenuous activity or competitive sport. Common forms of CHD include atrial and ventricular septal defects, patent ductus arteriosus, and atrioventricular canal. These conditions can range from mild to severe. Some, as in the case of small septal defects, may repair themselves spontaneously; others may require significant surgical intervention. Usually no special modifications in exercise testing modes are necessary for children with CHD. Many individuals with these defects can participate in a wide range of physical activities without modification. Those with pulmonary hypertension, arrhythmia, or evidence of myocardial dysfunction, however, may need to restrict their exercise to low-intensity activities as indicated by the 2005 Bethesda conference guidelines.
Cyanotic defects result in decreased oxygen delivery to the body with a subsequent alteration in skin coloration. This coloration is dark blue or purplish when the condition is severe. Numerous defects constitute this class of CHD (e.g., tetralogy of Fallot, tricuspid atresia, and pulmonary atresia; transposition of the great arteries; truncus arteriosus; and total anomalous pulmonary venous connection). A detailed description of the complex anatomy and physiology associated with each of these defects is beyond the scope of this chapter. Children with cyanotic defects often have mild to moderate decreases in their aerobic capacity. Those with significant residual problems following surgical repair may be more limited. Limitation in competitive sport increases as the degree of residual problems increases after surgery. Children with good surgical repair of these defects and those with no (or minimal) residual effects can often participate in various types of competitive sports (refer to the Bethesda conference guidelines for full recommendations). Postsurgery clients who experience oxygen desaturation during exercise require individualized exercise prescriptions.
Obstructive CHD occurs when one of the heart valves or blood vessels returning to or carrying blood from the heart becomes stenotic or atretic. The most common obstructive conditions are coarctation of the aorta and pulmonary and aortic stenosis. Defects of this type are classified from trivial to severe. As the severity of the defect increases, the potential for functional impairment also increases. Physical activity and competitive athletic competition restrictions are likely at the most severe levels of obstructive CHD. Children with mild to moderate obstructive CHD can normally participate in unrestricted or low-intensity levels of physical activity if the Bethesda conference guidelines are followed. Valvular stenoses may worsen as the child with CHD grows. Thus, regular assessment via echocardiography, exercise testing, and perhaps cardiac catheterization is usually necessary. Most children with obstructive CHD can perform modified Balke protocols as well as cycle ergometer protocols without significant alteration. Exercise evaluation of children with severe obstructive CHD may be contraindicated.
Any of these conditions or their treatments can have either a temporarily or permanently deleterious effect on growth and development. This should be addressed as appropriate with the child and his or her parents. Physical activity may be among the most effective means by which those effects can be offset.
The increased incidence of childhood obesity is well documented The Centers for Disease Control and Prevention (CDC) has compiled a normative table based on body mass index (BMI) for age and gender. Although some variation in the interpretation of the values exists, many consider children with a BMI between the 85th percentile and the 94th percentile to be overweight. Children at the 95th percentile and above are considered obese. Regardless of the interpretation or the definitions used, there is concern about the effects of obesity on health, both acutely and long term. The most serious acute risk in children, type 2 diabetes, is discussed next. The long-term chronic health conditions include cardiovascular disease, some types of cancer, and arthritis. Contributing factors to overweight and obesity include excessive energy intake and lack of caloric expenditure. Thus, poor eating habits, sedentary lifestyles, and lack of physical activity are the most frequently investigated issues concerning childhood overweight and obesity. Recommendations regarding overweight and obesity are presented in chapter 25.
Although treatment for diabetes mellitus (DM) has greatly advanced in recent years, the disease can make life difficult for children and their families. The freedom and spontaneity of childhood can be severely affected. Insulin-dependent diabetes mellitus (IDDM), the type previously associated with early onset and affecting only 5% to 10% of the population, is no longer the only concern for children. Increases in sedentary behavior and the resulting obesity markedly increases the incidence of childhood non-insulin-dependent diabetes mellitus (NIDDM), which was previously expected to occur in middle-aged persons. Thus, an increasing number of young people will be exposed to the consequences of DM for much longer time periods.
There is evidence regarding the benefits of exercise in the management of NIDDM, and to a lesser extent IDDM, through several mechanisms. The primary mechanisms include an increase in sensitivity to insulin, increases in glucose transport protein (GLUT-4), and glycogen synthase activity. Intestinal absorption of glucose may also be affected by exercise. A physically active lifestyle may aid in preventing or delaying the onset of NIDDM, primarily through the control of obesity, in all age groups. Additional benefits of regular activity include serum lipid reduction, increased aerobic fitness, and overall improvement in quality of life. The negative impact on social and psychological well-being can be mitigated for the child through involvement in a normally active lifestyle.
Precautions that should be considered for the diabetic (IDDM) child involved in physical activity include careful attention to preventing hypoglycemia by monitoring and regulating insulin levels and glucose intake. Special attention must be given to both the intensity and duration of the activity. High-intensity activity and physical exhaustion in young people with IDDM may cause an abnormal reaction, resulting in sustained hyperglycemia. Also, careful management of wounds and other injuries must be maintained. The stabilization of glucose levels is much more difficult in cases of IDDM than in those of NIDDM. Glucose control is much more structured, resulting in an even more severe intrusion into the life of the child. Nevertheless, the benefits are worth the effort. The more knowledgeable the child is about his or her daily care and the more involved, the more successful the management. If the diabetic child can get through the adolescent years in otherwise good condition, without excessive weight gain or other chronic conditions, the prognosis for health in the future is likely better. Exercise recommendations for individuals with diabetes are discussed in chapter 24.
A limited amount of research has been done on the implications of exercise testing and therapy for children affected by various progressive neuromuscular disorders (both congenital and acquired). Because the focus of this type of problem is on the muscular system, including muscular strength, endurance, power, and the metabolic cost of movement, all testing and therapeutic procedures should address these areas. Another area of concern relates to children with gait and coordination disorders that are often subclinical, thereby frequently receiving little or no attention.
Exercise testing can be effective in assessing and tracking delayed development or progressive deterioration in coordination as well as the efficacy of interventions. Although there are relatively few controlled studies, some evidence indicates that therapeutic modalities involving exercise training (aerobic, anaerobic, and resistance) may be beneficial in slowing the progression of some conditions and in maintaining or improving functional abilities. The difficulties involved in designing and carrying out the type of studies necessary to provide conclusive clinical data are significant. However, it seems reasonable that having affected children involved in appropriate physical activity would do no harm. Indeed, this would most likely yield some benefits related to normalizing growth and development.
Bronchial asthma (which includes exercise-induced asthma), and cystic fibrosis (CF), are the most commonly occurring chronic pulmonary diseases among children. Both of these conditions result in limitations on exercise tolerance and in cardiorespiratory responses that vary from those normally expected in children. Although chronic asthma attacks may be initiated by a number of environmental factors, such as allergens and pollution, exercise-induced asthma has been attributed to several mechanisms. These vary from the rather simple cooling, drying, and rewarming of the airways with increased ventilation to more complex effects involving chemical inflammation mediators. CF is an inherited condition of genetically defective sodium and chloride ion transport, which results in extracellular dehydration. Multiple organs and functions are affected by the thick mucus, which blocks ducts, tubules, and small airways. The function of affected organs, especially the lungs, is impaired to the point of causing early death. Although both asthma and CF can be life threatening, long-term survival and a relatively normal life can be expected with well-managed asthma. CF has a poor prognosis, however. Nevertheless, the benefits of regular exercise in persons with these disorders have been demonstrated. These relate mostly to improvement in aerobic fitness for both persons with asthma and those with CF and to increased ventilatory muscle endurance and strength in the individual with CF. The possibility of increased mucus clearance has also been reported, although benefits in pulmonary function are limited, if present at all. Caution is necessary when individuals with CF are exposed to heat and altitude. They are usually capable of normal thermoregulation, but special attention must be paid to fluid and electrolyte replacement. There is a risk of oxygen desaturation if oxygen tension in the environment is low.
The usefulness of exercise testing in diagnosis and prognosis determination for both conditions has been well documented. Determination of exercise tolerance and aerobic fitness not only is beneficial for the health care provider, but also instills confidence in both clients and parents.