Cardiovascular responses to exercise in childhood

Article Abstract:

Pediatricians are often consulted about children's exercise and physical fitness. Hence, they should be aware of the normal cardiovascular responses, or processes in the heart and circulation, that are activated in response to exercise. The cardiovascular responses to exercise in children and the differences in responses between adults and children are discussed. Exercise increases the energy expenditure of the body, which is measured by the amount of oxygen consumed (VO2). Oxygen is supplied to exercising tissue in relation to the intake of oxygen by the respiratory system and the delivery of oxygen by the blood to the tissues. Oxygen delivery is regulated by the cardiac output (CO), or the amount of blood pumped into the arteries per unit time. The increase in CO is determined by the heart rate (HR) and stroke volume (SV), the amount of blood emptied from the left ventricle at each heart beat. SV is affected by the distensibility, or ability to stretch, of the ventricles, and the force of contraction of the ventricle in relation to the pressure in the aorta, a main artery. Catecholamine hormones increase muscle contractility and heart rate and decrease systemic vascular resistance (SVR), the force in the blood vessels against which blood flows. The changes in these cardiovascular parameters with exercise are discussed. In conclusion, an increase in intensity of exercise is associated with increased VO2, CO, and HR. In addition, SV increases to maximum or highest levels at one-third of the maximum exercise intensity. An increase in CO is associated with an increase in systemic blood pressure and a decrease in SVR due to dilation of the blood vessels. The maximum oxygen consumption and ventilatory threshold, or point at which lactate accumulates in the blood, may serve as indicators of aerobic power in children. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Physiological aspects, Exercise, Exercise physiology, Cardiovascular system, Circulatory system, Exercise for children, Sports medicine

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Management of cardiovascular disease risk factors in children: a national survey of primary care physicians

Article Abstract:

A national survey of family physicians, general practitioners, and pediatricians showed that there were significant differences in the methods they used to treat factors associated with increased risk of cardiovascular disease in children between 2 and 18 years of age. Younger children tended to be screened more by pediatricians and were treated with conservative measures. Although older children were screened less by general practitioners, they tended to receive more aggressive therapy. Only 9 percent of physicians routinely measured blood cholesterol levels in children, whereas 72 percent of children who were screened had a family history of cardiovascular disease. Although most physicians measured blood pressure routinely, the age at which routine blood pressure measurements were started differed among physicians. Fifty-four percent of physicians had prescribed agents to lower blood pressure in children, while 12 percent had prescribed drugs to lower lipid levels. Although 50 percent of physicians were prepared to provide counseling on diet, only 14 percent were successful. Less than one-third of the physicians were able to identify hypertension, hypercholesterolemia (high blood cholesterol levels), and smoking as major cardiovascular risk factors. (Consumer Summary produced by Reliance Medical Information, Inc.)

Cardiovascular diseases, Prevention, Risk factors, Pediatric diseases, Coronary heart disease, Diseases

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