Journal of Obesity & Metabolic Syndrome

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Korean J Obes 2009; 18(3): 102-115

Published online June 1, 2009

Copyright © Korean Society for the Study of Obesity.

Comparisons of 12 Week Combined Exercise Intervention-mediated Changes
of Body Composition, Physical Fitness, and Metabolic Syndrome Risk Factors
According to IGF-I Gene Polymorphism in Obese Adolescent Boys

Nayoung Ahn, Kijin Kim*

Department of Physical Education, Keimyung University

Abstract

Background: The influence of Insulin-like growth
factor I (IGF-I) is considered to be an important
stimulatory factor in body composition, bone growth, cell
proliferation and metabolism.
Methods: The study analyzed the polymorphism of the
IGF-I gene among subjects composed of middle-school
male students (N = 21 obese group, N = 19 non-obese
group). Subjects' body composition, blood profiles, and
physical fitness were assessed. The changes in these
factors, prior to and post-exercise intervention, were
compared according to the difference in terms of IGF-1
gene polymorphism.
Results: Out of the total number of subjects, 62.5% had
one or two 19 CA (cytosine-adenosine) repeat, 71.4%
among the obese group and 52.6% among the normal
weight group. According to the IGF-1 gene polymorphism,
5 students (12.4%) were complete 19CA repeat (192 bp
allele) homozygous, 20 students (49.6%) were 19CA
repeat heterozygous, and 15 students (38%) were 19CA
repeat non-carriers. Body composition factors, such as
body fat ratio, had a tendency to be greater among the
homozygous group compared to either the heterozygous or non carrier groups, however no significant difference was
noted. Although no significant difference was noted in the
genotype polymorphism for either grip strength (Right) or
PEI, there was an increase in non-carrier group. Body fat
and HOMA-IR decreased in both groups, especially in the
obese group after the 12 week exercise intervention. In
contrast to the non-carrier groups, there was a significant
increase in change (P = 0.033) in sit up among the
homozygous and heterozygous groups of the obese group.
There was no significant difference in polymorphism of
grip strength (Right) among the homozygous group of the
obese group, however, it was far greater than that of the
other groups. Body composition of homozygous groups
increased in the IGF-I gene polymorphism but failed to
increase in other groups.
Conclusion: Grip strength and sit-up improved in
homozygous groups of the obese group after the 12 week
exercise intervention. However, further studies involving
greater number of subjects are needed to compare the
effects of exercise intervention in relation to IGF-I gene
polymorphism.

Keywords: IGF-I polymorphism, Adolescent, Exercise
intervention, Body composition