Current research clearly establishes the importance of physical activity and physical fitness to health, both in adults and children. However, taking into account the current low levels of physical activity and fitness among children, it is crucial that physical activity and fitness be promoted beyond the school and school day and into the home and community.
One of the key components of physical fitness is the exercising of the cardiovascular system. Thus, the purpose of this article is to discuss the cardiovascular adaptations to aerobic exercise in children, as well as its practical application.
Cardiovascular Adaptations to Aerobic Exercise
The cardiovascular systems of children seem to respond differently to exercise when compared to adults.1,2 One of the main adaptations to aerobic training is the ability of the heart to increase its pumping capacity (Cardiac Output L/min-CO) in response to increasing work load which, in turn, brings about an increase in maximum oxygen consumption (Vo2Max). The initial increase in CO at the onset of exercise is met by an increase in heart rate (HR) and stroke volume (SV). Stroke volume usually increases up to an intensity of 50 to 60 percent of Vo2Max, whereas HR continues to increase to maximum intensity. Similar to adults, children who undergo a well-controlled aerobic training program (i.e., treadmill running at > 80 percent of Vo2Max, three times per week for one hour for a duration of 13 weeks) do improve their cardiovascular fitness (i.e., Vo2Max).
However, the Vo2Max increases in children (5 to 10 percent) are lower than those usually seen in adults (15 to 30 percent) for similar training programs.2,3 For instance, children have lower cardiac output at a given oxygen consumption (Vo2) when compared to adults. In addition, heart rate recovery has been reported to be faster in children as compared to adults. Further, there appear to be no differences in gender as related to gains in cardiovascular fitness in children after an aerobic training program.3,4
In summary, children can increase their cardiovascular fitness when engaged in an aerobic training program.
In order to improve the cardiovascular component of physical fitness, the following guidelines should be taken into consideration when developing a supervised conditioning program for children. Note: Each child should receive an individualized program based on his or her strengths and weaknesses. The program described below is just a sample.
• Frequency: 3 times per week
• Intensity: Moderate
• Duration: 30 to 40 minutes
• Phase: 4 weeks
• Warm Up: 8 to 10 minutes. It should include dynamic activities such as brisk walking, skipping, light jogging, and jumping jacks, followed by static stretching (i.e., calves, hamstrings, lats).
• Aerobic Activity: Begin with 5 to 10 minutes total and gradually increase the duration at 5-minute increments up to 25 to 30 minutes (i.e., walking, cycling, swimming, jogging).
• Cool Down: Static stretches: hamstrings, quadriceps, calves, lats, piriformis, and neck.
In addition, according to the Council for Physical Education for Children, children should be involved in physical activity on most days of the week for 30 to 60 minutes (i.e., moderately intense activity).5
Children can improve their cardiovascular systems when properly trained. Thus, given the evidence that both increased physical activity and physical fitness in children are associated with improved risk factors for cardiovascular disease,6-9 it is important that children participate in a variety of physical activities to develop and maintain an acceptable level of cardiovascular fitness.
Dr. Kim Christensen is director of Chiropractic Rehab & Wellness services at PeaceHealth Hospital, Department of Rehab & Wellness, Physical Medicine & Rehabilitation in Longview, WA. A graduate of Western States Chiropractic College, he has been in active practice for 30 years. He is a postgraduate faculty member of numerous postgraduate chiropractic colleges and directs the chiropractic diplomate program. He may be reached by calling 1-360-414-2700 or e-mailing [email protected].
3. Mandigouts S, Lecoq AM, Courteix D, Guenon P, Obert P. Effect of gender in response to an aerobic training programme in prepubertal children. Acta Pediatric 2001;90:9-15.
5. Council for Physical Education for Children (COPEC). Physical Activity for Children: A Statement of Guidelines. Reston, VA: NASPE; 1998.
8. DuRant R, Baranowski T, Rhodes T, et al. Association among serum lipid and lipoprotein concentrations and physical activity, physical fitness, and body composition in young children. J Pediatrics 1993;123(2):185-193.