Mini review: physical activity and fitness and its relations to cardiovascular disease risk factors in children.

OBJECTIVES: This paper aim to review the newest literature linking physical inactivity and low fitness to metabolic disorders including cardiovascular disease (CVD) risk factors and obesity.
METHODS: There is a rationale for early prevention of CVD if (a) children have a risk factor profile, where risk for future disease is increased, (b) physical activity and CVD risk factors track into adulthood, and (c) increased physical activity can improve the risk factor profile. We reviewed the evidence for a progressive evolution of atherosclerosis starting in childhood, and also that physical activity decreases the rate of the process through several mechanisms. Among the central mechanisms mediating the effect of physical activity are (a) increased insulin sensitivity, (b) a non-insulin-dependent glucose uptake, which causes lower insulin release, (c) an improved ratio between HDL and LDL cholesterol because of increased activity of lipoprotein lipase, and d) improved function of other metabolic hormones and enzymes for fat metabolism.
RESULTS: The association between CVD risk factors and physical activity/fitness is weak, when risk factors are analysed isolated. In the normal healthy population of children, studies have shown that risk factors cluster and this clustering is strongly related to low physical activity or fitness. In European children it has been found that as many as 15% of 9-y-old children has clustered risk. Most of the overweight and obese children are among these, but many of the children are lean inactive children, who may later become overweight because of insulin resistance.
CONCLUSION: It can be concluded that there is a large potential for primary prevention of CVD in European children, and lifestyle changes including increased physical activity as one of the key actions should be initiated.