The purpose of this study was to ascertain whether exercise training cardiac adaptation exists in student rugby athletes, to define an adaptive pattern and to observe the student rugby athletics cardiac adaptive process. Subjects consisted of 42 male senior high school student rugby athletes, who participated in sports in junior high school, and a control group of sedentary students from the same senior high school who were matched for age. Student athletes were measured once a year over a three-year period. Left ventricular internal dimension at the end-diastole (LVIDd) and left ventricular posterior wall thickness at the end-diastole (PWT) were both measured by echocardiography. Because all subjects were growing adolescents, allometric scaling data (which is LVIDd/BSA^0.5 and PWT/BSA^0.5) was used for comparison, to preclude the effect of differences in body size on LVIDd and PWT. Cross-sectional comparisons of athletic students with controls were conducted for each of the three senior high school grades, respectively. The data of student athletes during the three-year study was used for longitudinal comparisons. The results of cross-sectional comparisons showed that LVIDd/BSA^{0, 5} in a student athlete group consisting of the three grades combined was greater than the corresponding control group (P<0.05, P<0.01, respectively) . PWT/BSA^0.5 in the athletic group was greater than the control group for the third grade level (P<0.05) . The results of the longitudinal comparison revealed that no significant differences were present in LVIDd/BSA^0.5 during the three-year investigation (P>0.05, respectively) . PWT/BSA^0.5 at the second and third grade level were obviously greater than at the first grade level (P<0.05, respectively) ; however, no dif. ference between the second and third grade levels existed. The results of this present study suggest that regular rugby exercise training during senior high school obviously induced left ventricular posterior wall thickening in the athletic students. An enlarged left ventricular cavity was observed at the first grade level of senior high school and did not significantly change during three years of senior high school.

Masked obesity is the presence of obesity based on percent body fat (%BF) when the body mass index (BMI) shows an absence of obesity. To examine the relationship between masked obesity and arteriosclerosis risk factors, we compared both serum lipid levels and the prevalence of hyperlipidemia in male and female high school freshmen with and without masked obesity. Subjects consisted of 403 male and 326 female high school students aged 15∼16 years. Of these, 34(8.4%) males and 36(11.0%) females had masked obesity, defined as 17≤BMI<23.60 and %BF≥25% in males, and 17≤BMI<24.17 and %BF≥30% in females, while the remaining 300 males and 246 females were not obese, having 17≤BMI<23.60 and %BF<25% and 17≤BMI<24.17 and %BF<30%, respectively. For both sexes, serum total-cholesterol (TC), low-density lipoprotein cholesterol (LDLC), triglycerides and the arteriosclerotic index (AI) were significantly higher (p<0.05∼0.01) in those with masked obesity. And many of the subjects with masked obesity had abnormal levels of TC, LDLC and AI, compared with those who were not obese (p<0.05∼0.01). Additionally, we compared both serum lipid levels and the prevalence of hyperlipidemia between subjects with masked obesity and control groups with the same BMI values. As a result, subjects with masked obesity had high serum lipid levels and a prevalence of hyperlipidemia. These results support the existence of masked obesity and suggest that masked obesity is associated with increased serum lipid levels, and thus could be a risk factor for arteriosclerosis in male and female high school freshmen.

The purpose of this study was to investigate the effects of short-term living and training at an altitude of 1, 300 to 1, 800 m on physiological responses of high school elite endurance athletes. Fifteen male and seven female senior high school elite athletes, aged from 15 to 18, from three different sports (cross-country skiing, long-distance running and endurance cycling), participated in our study. The short-term (6 days) altitude exposure did not elicit abnormal responses of body tempera-ture, body weight, blood pressure or urine samples. There were also no significant changes in blood parameters examined before and after altitude exposure. Resting heart rate (HR) increased at altitude and presented an initial peak value followed by a steady decline on the following days of altitude exposure. Blood lactate concentration and exercise peak llR examined by submaximal 20-m shuttle run test decreased after the ascent to altitude and still showed lower values at postaltitude than at prealtitude. We conclude that 6-day living and training at an altitude of 1, 300 to 1, 800 m elicits positive decrements of exercise blood lactate and exercise peak HR as well as adaptive changes of resting IlR for these high school elite endurance athletes, which are probably related to an attenuation of muscle glycogen utilization and alterations in the autonomic neural system taken at altitude.