Medicine & Science in Sports & Exercise:
F-23 Free Communication/Poster - Bone: June 1, 2007 1:00 PM - 6:00PM ROOM: Hall E
1Univ of Tartu, Tartu, Estonia.
2University of Bologna, Bologna, Italy.
PURPOSE: To assess the influence of pubertal status and regular physical activity on ghrelin concentration; and to examine the association of fasting plasma ghrelin concentration with bone mineral parameters in prepubertal and pubertal boys with different physical activity pattern.
METHODS: In total, 63 healthy schoolboys aged between 10 and 16 years were divided into swimming (n=29) and control (n=34) subjects. The subjects were matched for body mass index (BMI), generating 9, 11 and 8 matched pairs for groups I (Pubertal stage I), II (Pubertal stages II & III) and III (Pubertal stage IV), respectively.
RESULTS: Significant maturation effect for bone mineral density (BMD) and lumbar apparent volumetric BMD (BMAD) values were observed for control and total groups during the pubertal development, while no further maturation effect for BMD and BMAD values were observed in swimmers between Pubertal stages II & III and Pubertal stage IV. Plasma ghrelin concentration was not differnt in swimmers at different maturation levels. Control boys at Pubertal stages II & III and Pubertal stage IV had significantly lower values for ghrelin compared to prepubertal (Pubertal stage I) control boys. Control boys at Pubertal stage IV had significantly lower values for ghrelin concentration compared to the swimmers at the same maturation level. Plasma ghrelin was significantly related to total BMD, lumbar BMD and BMAD values. The correlation of plasma ghrelin with total BMD was no longer significant after adjustment for age, biological maturation, height and fat free mass. In contrast, plasma ghrelin was still related to lumbar BMD (r=−0.256; p=0.049) and BMAD (r=−0.279; p=0.032) after adjustment for these confounding variables. However, the correlation of plasma ghrelin with total BMD, lumbar BMD and BMAD was no longer significant (r<-0.129; p>0.332) after adjustment for age, biological maturation, testosterone and IGF-I values.
CONCLUSION: Ghrelin concentration was decreased during puberty in physically inactive boys, while ghrelin concentration remained relatively unchanged in regularly physically active boys. Plasma ghrelin concentration was related to BMD and BMAD independent of body size values. However, this association was mediated through sex hormones and IGF-axis.