Effects of endurance training on blood lipid profiles in adolescent female distance runners

The purpose of this study was to investigate the cross-sectional and longitudinal effects of endurance training on the relationships of body composition, blood lipid profiles and sex hormones in adolescent female distance-runners. We cross-sectionally compared body composition, blood lipid profiles and blood sex hormones of non-athletes (n=7) and distance-runners (n=8), with the similar lower level of BMI (17.1 kg/m(2) vs. 18.7 kg/m(2), respectively). After the cross sectional comparison on the influence of endurance training, body composition, blood lipid profiles and blood sex hormones were examined at pre- and post-one year endurance training in the distance-runners (n=6) to determine longitudinal effects. %Fat in distance-runners revealed a tendency to be lower than that in non-athletes (23.8+/-3.5 vs 27.3+/-2.5%). Both groups showed good blood lipid profiles, such as high levels of high density lipoprotein-cholesterol (HDL-c), HDL-2c, and apolipoprotein A-I (ApoA-I). However, the estrogen (E(2)) level of distance-runners was less than one third of that in non-athletes (30.5+/-11.3 vs 112.9+/-66.2 pg/ml, p<0.01). In addition, the blood E(2) levels (pg/ml) were significantly associated with the internal fat mass (IF, kg) in all subjects (r=-0.613, p<0.05, n=15). On the other hand, the overall body composition and good blood lipid profiles in the longitudinal comparison were maintained to a constant level for one year endurance training, except for significant elevations in the two enzyme activities and E(2) level (LPL activity: from 145.3+/-40.8 to 362.2+/-65.8 ng/ml, HTGL activity: from 0.054+/-0.020 to 0.173+/-0.080 micromole/ml/min, E(2): from 30.7+/-13.2 to 65.6+/-24.2 pg/ml, p<0.05). These results suggest that the lipid profiles such as HDL-c and Apo A-I in adolescent female distance-runners could be rather affected by endurance training, despite the low level of E(2) for a long term.