Comportamento das variáveis cardiovasculares, ventilatórias e metabólicas durante o exercício: diferenças entre crianças e adultos

Abstract

With the growing popularity and emphasis on the benefits of physical conditioning in children, it is important to understand the physiological aspects of exercise in the pediatric population. Children should not be seen as "miniature adults" 1 ; they are unique and have singular traits at each phase of growth. Development of the skeletal muscle, nervous, and endocrine systems largely determines their physiological and metabolic limits under physical exertion 1,2. Currently, there is a growing interest in research on growth and physiological development in children and adolescents, and consequently on the mechanisms involved in the cardiorespiratory and metabolic behavior of the pediatric population during physical exercise. In fact, certain authors 2-5 attribute the different physiological and metabolic responses observed in children during physical exercise to their level of biological maturation, since as they grow, they also develop in almost all functional capacities. In an elegant study carried out by Vinet et al 3 , it was noted that prepubertal children have the lower values of cardiac output at peak exercise when compared to young adults. As to cellular metabolism, several studies have observed that children have less efficient glycolytic activity during physical exercise compared to adults 1,5-7. During the pubertal growth spurt, important hormones (somatotropin, growth factors similar to insulin, and sexual steroid hormones) are released into the blood stream 1,2. There is an increase in lean body mass, and this change in body composition has a positive influence on the development of physical capacities and performance during puberty. Therefore, several aspects of biological adaptations to exercise in children and adolescents should be considered. Which physiological alterations in response to exercise occur with age, when children and adolescents have the same absolute energy expenditure in performing their tasks? Are there significant differences in cardiovascular, ventilatory, and metabolic responses to different demands (submaximal or maximal) of exercise in the growing individual? (Tab. 1) We present various studies that show the possible morphofunctional mechanisms that characterize cardiovascular, ventilatory, and metabolic responsiveness during physical effort observed in children.