Effect of acute and chronic exercise on ghrelin and adipocytokines during pubertal development.

It is important to understand the factors that regulate the development of obesity during adolescence due to the increased risk of adult obesity, metabolic syndrome and the deleterious health effects of early puberty which may increase the risk of breast cancer later in life. Leptin, ghrelin, and adiponectin are peptides that affect energy homeostasis and insulin action. Similar to findings in adults, steady-state exercise does not change leptin concentrations and aerobic training without a change in body weight. A small amount of available data suggest that acute exercise does not increase circulating adiponectin concentrations in adolescents; however, it is very possible that more rigorous exercise protocols could acutely affect circulating adiponectin levels. Training studies indicate that shorter lengths of exercise training have a stronger effect on increases in adiponectin concentrations in male than female adolescents. It appears that if training is extended, increases in adiponectin levels will accompany improvements in insulin sensitivity. There are no studies of acute or chronic exercise on high-molecular weight adiponectin in adolescents and since this is thought to be the bioactive form of adiponectin, these studies are definitely needed. Investigations have demonstrated that exercise training increases total ghrelin levels in adolescents and that ghrelin is sensitive to reductions in body fat or increases in energy expenditure in this population. These findings are similar to those in adults. Moreover, there is evidence that luteinizing hormone is a predictor of total ghrelin levels in girls and suggests that ghrelin is a biomarker of energy imbalance across the menstrual cycle.