PT Weekly: Pediatric Cardiomyopathy and Exercise Therapy

Cardiovascular Disease describes a range of conditions that affect your heart which include; blood vessel diseases, such as coronary artery disease; heart rhythm problems (arrhythmias); and heart defects you’re born with (congenital heart defects), among others. The term “heart disease” is often used interchangeably with the term “cardiovascular disease.”

Cardiovascular disease generally refers to conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain (angina) or stroke.

Other heart conditions, such as those that affect your heart’s muscle, valves or rhythm, also are considered forms of heart disease.

Cardiomyopathy is a term that is used to describe a pathology of the heart muscle. There are a number of types of cardiomyopathy.

Below we explain three of them.

Dilated cardiomyopathy

This is a term used to describe an enlarged heart. The heart muscle is quite saggy and cannot pump as well as normal. Sometimes the pump may not be able to pump efficiently around the body and this leads to a build up of fluid in the lungs and cause breathlessness.

There are a number of causes of cardiomyopathy; heart attack , high blood pressure, alcohol. Sometimes however it is difficult to find a cause. This is called an idiopathic cardiomyopathy.

Hypertrophic Cardiomyopathy

This diagnosis is reached when there is thickening of the heart muscle for no reason. It is different to thickening due to high blood pressure or athletic training. Excessive exertion is limited in this condition but moderate level exercise can be beneficial.

Restrictive cardiomyopathy

This is a condition where the heart muscle becomes quite stiff. This means that the heart cannot fully relax so it cannot fill up with blood as well so in turn cannot pump blood around the body efficiently.

Children with cardiomyopathy carry significant risk of morbidity and mortality. New research and technology have brought about significant advancements to the diagnosis and clinical management of children with cardiomyopathy. However, currently heart transplantation remains the standard of care for children with symptomatic and progressive cardiomyopathy. Cardiovascular rehabilitation programs have yielded success in improving cardiac function, overall physical activity, and quality of life in adults with congestive heart failure from a variety of conditions.

There is encouraging and emerging data on its effects in children with chronic illness and with its proven benefits in other pediatric disorders, the implementation of a program for with cardiomyopathy should be considered. Exercise rehabilitation programs may improve specific endpoints such quality of life, cardiovascular function and fitness, strength, flexibility, and metabolic risk. With the rapid rise in pediatric obesity, children with cardiomyopathy may be at similar risk for developing these modifiable risk factors.

However, there are potentially more detrimental effects of inactivity in this population of children. Future research should focus on the physical and social effects of a medically supervised cardiac rehabilitation program with correct determination of the dosage and intensity of exercise for optimal benefits in this special population of children. It is imperative that more detailed recommendations for children with cardiomyopathy be made available with evidence-based research.

1. Types of Exercise

The individual sessions of a cardiac rehabilitation program should be divided into component parts; aerobic, resistance and flexibility training. All three of these components contribute differently to the general health of individuals. In the prescription of an individualized rehabilitation program, the F.I.T.T. Principle (Frequency, Intensity, Time, and Type) should be implemented, where each component of the exercise program satisfies this principle. Frequency refers to how often the exercise sessions are completed (e.g. two times per week), Intensity is the level of exertion during exercise (e.g. 60% of maximal heart rate), Time refers to the duration of the exercise session (e.g. 45 minutes), and type refers to the specific activity completed (e.g. treadmill). An example of the FITT principle applied to the aerobic component would consist of activity two times per week, in 30-minute sessions, at 50–75% of maximal heart rate, on a cycle ergometer. Similar to the food pyramid for nutrition, a physical activity pyramid indicates the amounts and types of physical activity that should be practiced.

a. Aerobic Training

Aerobic exercises are defined as “any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature” . Aerobic exercises are comprised of activities that cause the lungs and heart to function at higher levels in order to provide adequate substrates to working muscles over an extended period of time. According to the American Heart Association (AHA) and the American College of Sports Medicine (ACSM), aerobic exercises should be performed at least five days per week. The options for aerobic exercises are endless and the selection of activities that are fun and/or entertaining to the child should remain front and center when prescribing them. Fun activities will promote sustainability and compliance. Recent studies have shown promising results in children who use virtual reality game systems to augment physical activity.

b. Resistance Training

Resistance training is composed of dynamic movements with progressive overload to increase and improve muscular strength. Previous studies may have been misinterpreted and caused great alarm regarding the safety and long-term adverse consequences of resistance training programs in children. Current evidence suggests that both prepubescent and adolescent children, can increase muscular strength by following a strength-training regimen without additional risk of injury.

Furthermore, exercise intervention studies in children, with a resistance-training component, have been published and adverse events have not been reported. Authors acknowledge the potential for injury is greater in this population, but emphasize the need for trained personnel and close supervision of the pediatric participants. Resistance training is recommended 2–3 times per week incorporating all major muscle groups.

For children and adolescents, the goal of a resistance-training program should aim to improve overall body strength with muscular hypertrophy deemphasized.

Circuit training programs that emphasize aerobic conditioning while engaging in resistance training have been proven beneficial, in children. Careful selection of equipment is necessary and important as placing a small child on adult-sized equipment may lead an unnatural alignment of joints and muscle groups. In general, resistance-training machines are safer than free weights as they allow a fixed pattern of movement, and are easier to learn. Free weights require much more coordination and accessory strength for proper completion of the exercise thus placing a child at greater risk for injury.

Training protocols that prescribe a higher number of repetitions, rather that greater weight, are more effective for children during their first stages of resistance training. There is no evidence that children lose flexibility with strength training. Soon after beginning a strength-training program, it is common to appreciate significant improvements in strength. Initially there are improvements in motor learning, and efficiency of the task due to neuromuscular adaptations to exercise although no significant changes occur at the muscle fiber level. After the acute response, muscle hypertrophy occurs. Hypertrophy is defined by increases in size of the muscle (through increase in myofibrils). Hypertrophy leads to more metabolically active tissue thus generating and utilizing more energy.

c. Flexibility Training

Flexibility training progressively increases the range of motion of a joint or set of joints over a period of time.. Flexibility exercises can be completed in both dynamic or static positions. Benefits include increased range of motion, muscular relaxation, less chance of injury and less muscular soreness, to name a few.

Flexibility exercises should be preceded by warm-up activities to increase local blood flow to the working muscles. Flexibility exercises should be performed 2–3 times per week and to include exercises for all major muscles groups. All stretches should be performed to the point of mild discomfort, with a sustained stretch for 30–60 seconds.

2. Effects of Exercise on Children with Cardiomyopathy

There is a dearth of information regarding the effect of cardiac rehabilitation programs for children with cardiomyopathy. However, it is reasonable to expect that implementing an exercise rehabilitation program in the context of state-of-the-art medical therapies may provide added benefits for children with cardiomyopathy, since these children have lower functional capacities.

The decrease in functional capacity is caused, in part, by their cardiovascular disease, but overall physical inactivity is also a contributing factor. Ideally, improved cardiac function and other cardiac biomarkers would provide the greatest evidence for the benefit of exercise rehabilitation in pediatric cardiomyopathy, but functional improvements such as quality of life and decreasing any concomitant cardiac risk factors are equally important.