ABSTRACT
[Purpose] This study aimed to examine the correlation of visfatin level to pancreatic endocrine hormone level, homeostasis model assessment of insulin resistance (HOMA-IR) index, and HOMA ß-cell index in hydraulic resistance exercise. Furthermore, it investigated the relationship between visfatin level and other variables affected by exercise in overweight women. [Subjects and Methods] The exercise group trained for 12 weeks, 70 minutes/day, 5 days/week. Visfatin level, pancreatic endocrine hormone level, HOMA-IR index, and HOMA ß-cell index were measured before and after the intervention. Based on the blood insulin and glucose concentrations, HOMA-IR index, the indicator of insulin resistance, and HOMA ß-cell index, the indicator of insulin secretion level, were assessed. [Results] Interaction effects on visfatin level, insulin level, HOMA-IR index, and HOMA ß-cell index were observed. Interaction effects on glucagon and glucose levels were not observed between the intervention groups. The correlations of visfatin level to insulin, glucagon, and glucose levels, and HOMA-IR and HOMA ß-cell indexes were not significant for any of the subjects. [Conclusion] Therefore, the 12-week resistance exercise affected body composition, visfatin level, insulin level, HOMA-IR index, and HOMA ß-cell index. Finally, visfatin was not related to insulin, glucagon, and glucose levels, and HOMA-IR and HOMA ß-cell indexes.
ABSTRACT
The purpose of this study was to investigate differences in the prevalence of obesity among Korean adolescents and to determine the relationship of obesity prevalence with weekly frequency of physical education (PE) classes. In 2009, 72,399 students from grades 7 to 12 participated in the fifth Korea Youth Risk Behavior Web-based Survey (KYRBWS-V) project. Body mass index (BMI) and the frequency of PE classes attended were assessed by the KYRBWS- V. BMI was computed to classify the participants as underweight, normal weight, overweight, and obese. The association between the frequency of PE classes and BMI were examined using one-way ANOVA and logistic regression analysis. The differences in the weekly frequency of PE classes and the BMI values among both the boys and girls were significant (p < 0.001). A post-hoc test showed that underweight boys and girls attended the PE classes more frequently (p < 0.001), and overweight girls attended these classes less frequently (p < 0.01) than the other groups did; moreover, obese boys and girls, compared to boys and girls in the other groups, attended less number of PE classes per week while at school (p < 0.05). Besides, the odds ratio (95% confidence interval, CI) for normal-weight vs. underweight boys attending 1 PE class, 2 PE classes, and ≥ 3 PE classes per week were 1.168 (1.011-1.349, p = 0.035), 1.621 (1.450-1.812, p < 0.001), and 3.023 (2.704-3.381, p < 0.001), respectively, compared with those for boys who did not attend PE classes. The OR (95% CI) of normal-weight vs. obese boys attending ≥ 3 PE classes attended across normal vs. obese boys was 0.862 (0.762-0.974, p = 0.017), compared with those of boys who did not attend PE classes. The OR (95% CI) for normal-weight vs. underweight girls who attended 2 PE classes and ≥ 3 PE classes per week were 1.235 (1.131-1.349, p < 0.001) and 2.238 (2.048-2.446, p < 0.001), respectively, compared with those of girls who did not attend PE classes. The OR (95% CI) of for normal-weight vs. overweight girls who attended ≥ 3 PE classes per week were 0.886 (0.787- 0.997, p = 0.045) and 0.772 (0.679-0.878, p < 0.001), respectively, compared with those of girls who did not attend PE classes. The OR (95% CI) for normal-weight vs. obese girls who attended 2 PE classes and ≥ 3 PE classes per week were 0.788 (0.675-0.919, p = 0.002) and 0.709 (0.599-0.838, p < 0.001), respectively, compared with those of girls who did not attend the PE class. Increase in the frequency of PE classes should be considered in any attempt for curbing weight-related problems in Korean adolescents. Key pointsIncrease in the frequency of PE classes is a factor that should be considered to improve weight status.
ABSTRACT
Previous research clearly indicates a linear relationship between exercise intensity and growth hormone (GH) release and that this relationship is influenced by sex. The present study examined the GH response to increasing exercise duration in young men and women. Fifteen healthy subjects (8 men and 7 women) completed three randomly assigned exercise sessions (30, 60, and 120 min) at 70% of peak oxygen consumption. Blood samples were collected every 10 min beginning 30 min before exercise, for a total of 240 min. Total integrated GH concentration (IGHC) increased with increasing exercise duration for men and women (601, 1,394, and 2,360 microg/l.4 h; 659, 1,009 and 1,243 microg/l.4 h for 30, 60, and 120 min of exercise, respectively). Regression analysis revealed that IGHC (logarithmically transformed) was significantly influenced by exercise duration (logarithmically transformed) (120 min > 60 min > 30 min) and that a significant sex-dependent effect was present even after adjustments for fitness level and percent body fat (men > women). The slope of the regression line was greater for men than for women (1.003 vs. 0.612; P = 0.013), but the average height of the regression line was greater for women (7.287 vs. 6.595; P < 0.001). Although GH secretory pulse half-duration was greater in women (P = 0.001), and GH half-life was greater in men (P = 0.001), they were not affected by exercise duration. The total mass of GH secreted during exercise increased with exercise duration (P < 0.001) but was not affected by sex (P = 0.137). Results from the present investigation indicate that when exercise intensity is constant, exercise duration significantly increases IGHC and that this relationship is sex dependent.