Effect of exercise training on erythrocyte insulin-like growth factor-I receptor binding in adolescent males

IGF-I receptor 275124A>C (rs1464430) polymorphism and athletic performance

OBJECTIVES

To examine the prevalence of the Insulin-Like Growth Factor-I receptor (IGF-IR) 275124A>C polymorphism, known to be associated with exercise-related cardiac hypertrophy, among elite endurance and power athletes.

DESIGN

One hundred and fifty-nine athletes (118 men and 41 women, age: 35.9±12.2 yrs) participated in the study.

METHODS

We hypothesized that presence of the A allele will be significantly more common among endurance athletes (n=77) compared to power athletes (n=82) and non-physically active controls (n=68). Athletes within each group were further divided according to their individual best performance into elite athletes (those who had represented the country in international track-and-field or triathlon competitions or in the Olympic Games) and national-level athletes.

RESULTS

The prevalence of the AA genotype was significantly higher (p<0.05) in the endurance athletes group (49%) compared to the power athletes group (33%), but did not differ from the control group (46%). There was no significant difference in the prevalence of the AA genotype between elite and national level endurance athletes (44% versus 52%, respectively). In contrast, among power athletes, the prevalence of the AA genotype was significantly lower in the elite compared to national level athletes (17% versus 42%, respectively; p<0.05).

CONCLUSIONS

The results of the present study may suggest that the IGF-IR AA polymorphism is beneficial for endurance-type sports, but is not associated with elite endurance performance. In contrast, the presence of the AA genotype may be a disadvantage in power sports. All together the results of the present study suggest that IGF-IR polymorphism may differentiate between the two edges of the endurance-power athletic performance spectrum.

Hormonal response to Taekwondo fighting simulation in elite adolescent athletes

Exercise training efficiency depends on the training load, as well as on the athlete's ability to tolerate it. The aim of the present study was to evaluate the effect of fighting simulation (3 fights, 6 min each, 30 min rest between fights) on anabolic (IGF-I, LH, FSH, estradiol, and testosterone) and catabolic hormones (cortisol) in elite, male (n = 10) and female (n = 10) adolescent (12-17 years) Taekwondo fighters. Blood samples were collected before the first and immediately after the third fight. The fighting simulation practice led to significant (p < 0.05) decreases in IGF-I (males -27.1 ± 25.6, females -22.4 ± 36.3 ng/ml), LH (males -0.7 ± 1.2, females -2.3 ± 3.3 U/L), and FSH (males -0.9 ± 0.5, females -1.5 ± 1.1 U/L), and to a significant increase (p < 0.05) in cortisol (males 141.9 ± 30.1, females 64.1 ± 30.6 mcg/dL) in both genders. Fighting simulation decreases in testosterone (males -1.9 ± 1.6, females -0.02 ± 0.06 ng/mL), and free androgen index (males -20.1 ± 21.5, females -0.3 ± 0.5) were significant (p < 0.05) only in male fighters. Exercise had no significant effect on estradiol, sex-hormone-binding globulins or thyroid function tests. Our data demonstrate that the physiologic and psychologic strain of a Taekwondo fighting simulation day led to a catabolic-type circulating hormonal response.