Endocrinology and Pediatric Exercise Science-The Year That Was 2017.

The Pediatric Exercise Science "Year That Was" section aims to highlight the most important (to the author's opinion) manuscripts that were published in 2017 in the field of endocrinology and pediatric exercise science. This year's selection includes studies showing that 1) in pubertal swimmers, there is a decrease in insulin-like growth factor-1 (IGF-I) and IGF-binding protein-3 (IGFBP-3) during intense training (a catabolic-type hormonal response) with an anabolic "rebound" characterized by a significant increase of these growth factors during training tapering down. Moreover, it was shown that changes of IGF-I and IGFBP-3 paralleled changes in peak and average force but not with endurance properties, showing decreases during intense training and increases during tapering; 2) a meta-analysis showing that growth hormone administration elicits significant changes in body composition and possible limited effect on anaerobic performance but does not increase either muscle strength or aerobic exercise capacity in healthy, young subjects; and 3) short-term exercise intervention can prevent the development of polycystic ovary syndrome in a dose-dependent manner in letrozole-induced polycystic ovary syndrome rat model with high-intensity exercise being most effective. The implication of these studies to the pediatric population, their importance, and the new research avenues that were opened by these studies is emphasized.