[Relationship between physical activity and physical fitness in children and adolescents].

Physical activity in adults is associated with a lower risk of obesity, cardiovascular disease, high blood pressure, diabetes, cancer, and premature death. There is considerable evidence that cardiovascular disease has its origins in childhood and adolescence. Lipid and lipoprotein profiles, blood pressure, and adiposity in young people tend to persist over their lifetimes (tracking).1 There is also evidence that behavioral patterns of physical activity in childhood are maintained throughout adulthood.2 Childhood and adolescence are therefore key to the primary prevention of cardiovascular disease and other conditions associated with a sedentary lifestyle. This is particularly true when we take into account the difficulty involved in modifying adult lifestyles. Although it is usually assumed that more active children will have higher levels of physical fitness, and that the relationship is causal, the assumption may no longer be valid in the light of current knowledge. Only a small amount of the variation in different measures of physical fitness in children and adolescents can be attributed to physical activity. Measures of physical activity and physical fitness also show great variability. In order to examine the relationship between these 2 concepts in more detail, it is perhaps best to start by defining them. The terms “physical activity,” “physical exercise,” and “physical fitness” are often confused. Although they are closely related, they should not be treated as synonyms. “Physical activity” refers to any bodily movement produced by skeletal muscle which requires consumption of energy. “Physical exercise,” on the other hand, is defined as any planned, structured, and systematic physical activity designed to improve or maintain one or more components of physical fitness. “Physical fitness” in turn can be interpreted as a measure of the capacity to perform Relationship Between Physical Activity and Physical Fitness in Children and Adolescents