Chang-Duk Ha

Effect of walking exercise on abdominal fat, insulin resistance and serum cytokines in obese women

[Purpose] The purpose of the study was to investigate the effect of 12-week walking exercise on abdominal fat, insulin resistance and serum cytokines in obese women. [Methods] Following baseline measurements, obese women (N = 20) who met obesity criterion of BMI at 25 kg/m2 or greater were randomly assigned to the control (n = 10) or exercise groups (n = 10). Women assigned to the exercise group participated in a walking exercise (with an intensity of 50-60% of predetermined VO2max, a frequency of 3 days per week and duration of 50-70 minutes targeting 400 kcal of energy expenditure per session) for 12 weeks, while women assigned to the control group maintained their sedentary lifestyle. After the 12-week walking intervention, post-test measurements were conducted using the same procedure as the baseline measurement. Analyses of variance with repeated measures were used to evaluate any significant time by group interactions for the measured variables. [Results] With respect to body fat parameters, significant time-by-group interactions were found in the abdominal subcutaneous (p = < 0.001) and visceral adipose tissues (p = 0.011). The exercise group had significant reductions in both subcutaneous and visceral adiposity, and the control group had no significant changes in those parameters. Similarly, there were significant time by group interactions in fasting glucose (p = 0.008), HOMA-IR (p = 0.029), serum TNF-α (p = 0.027), and IL-6 (p = 0.048) such that the exercise group had significant reductions in those parameters, with no such significant changes found in the control group. The exercise group also had a significant increase in serum adiponectin (p = 0.002), whereas the control group had no significant change in the parameter. [Conclusion] In summary, the current findings suggest that walking exercise can provide a safe and effective lifestyle strategy against abdominal obesity and serum insulin resistance markers in obese women.

Serum Vitamin D, Physical Activity, and Metabolic Risk Factors in Korean Children.

PURPOSE The purpose of this study was to investigate the relationship of serum vitamin D levels with lifestyle factors, including body fatness and physical activity (PA) parameters, and the clustering of metabolic risk factors in the Korean pediatric population. METHODS Serum 25-hydroxyvitamin D levels, accelerometer-based PA, and body fatness and metabolic syndrome parameters were assessed in a sample of children of Korean descent (N = 310). Correlation and multivariate linear regression were used to explore the relationships among serum vitamin D levels, lifestyle factors, and the clustering of metabolic risk factors in the study sample. RESULTS Serum vitamin D levels were negatively associated with body fatness parameters, including body mass index, percent body fat, and waist circumference, but positively associated with accelerometer-based PA including low, moderate, and vigorous levels. In addition, serum vitamin D levels were inversely related to total cholesterol, triglycerides, fasting glucose, and insulin. A stepwise linear regression model showed that both low serum vitamin D levels and decreased vigorous PA were independent predictors for individual variation in the clustering of metabolic risk factors in this study sample. CONCLUSION The results of this study suggest that an increase in vigorous PA and vitamin D intake should be two major targets of public health inventions against the clustering of metabolic risk factors in the Korean pediatric population.

Relationship of PGC-1α Gene Polymorphism With Insulin Resistance Syndrome in Korean Children:

This study aimed to investigate the associations between peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) gene Gly482Ser polymorphism (rs8192678) and parameters of insulin resistance in a sample of Korean children. A total of 286 children aged 10 to 12 years old were recruited from local elementary schools. Measured variables included body fat, blood pressures, blood lipids, glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and accelerometer-based physical activity (PA). Significant differences in percentage body fat (P = .016), insulin (P = .013), and HOMA-IR (P = .007) were found according to Gly482Ser genotype, with no significant genotype differences in the other measured variables. The genotype-specific differences in insulin (P = .136) and HOMA-IR (P = .067) were significantly attenuated when adjusted for age, sex, Tanner stage, body fat, and PA. The findings of the study suggest that the genetic effects of the PGC-1α genotypes on parameters of insulin resistance might be modulated by lifestyle factors, including PA and body fatness.

Roles of physical activity and cardiorespiratory fitness on sex difference in insulin resistance in late elementary years

[Purpose] Little is known about the potential role of lifestyle factors in sex differences in insulin resistance in late elementary school children. [Methods] In this cross-sectional study, we compared sex differences in Tanner scales, body fat, physical activity (PA) and fitness, and insulin resistance markers in elementary school children (boys, n = 69 and girls, n = 81) aged 12-13 years. Body composition was assessed with a standardized protocol. Cardiorespiratory fitness was measured as oxygen consumption during an incremental treadmill exercise. Fasting blood samples were collected for blood chemistry assays including lipids, glucose, insulin and homeostasis model assessment for insulin resistance (HOMA-IR), leptin, and adiponectin. Daily PA was measured with an accelerometer for 7 consecutive days, and they were classified as low-, moderate-, and vigorous-PA. Independent t-tests were used to compare mean differences in the measured variables between boys and girls. There were significant sex differences in Tanner scales, body mass index, percent body fat, and waist circumference (WC). [Results] Girls had significantly higher values in Tanner scales (p < 0.001) and percent body fat (p < 0.001) than boys. Boys had significantly higher values in body mass index (p = 0.019) and waist circumference (p < 0.001) than girls. Boys also had significantly higher values in VO2max (p < 0.001) and low (p < 0.001), moderate (p < 0.001), and vigorous (p < 0.001) PAs. With respect to metabolic risk factors, girls had significantly higher serum levels of triglycerides (p = 0.005), insulin (p < 0.001), and HOMA-IR (p < 0.001) and significantly lower high-density lipoprotein cholesterol (p = 0.015) than boys. [Conclusion] In summary, the current findings of the study showed that the increased risk for insulin resistance in girls over boys is associated with higher Tanner scale and percent body fat in conjunction with poor cardiorespiratory fitness and physical inactivity, suggesting that exercise intervention to promote physical activity and fitness is imperative for general health promotion of school children, with a special focus on girls.

Association between serum vitamin D status and metabolic syndrome in Korean young men.

PURPOSE This study examined the relations of serum vitamin D levels to body fatness, cardiorespiratory fitness (CRF), and metabolic risk factors in young adults in Korea. METHODS Between 2007 and 2009, 799 young men completed a health examination. Body fatness, CRF based on a maximal treadmill exercise test, and measurements of metabolic risk factors were measured in study participants. Participants were classified by serum vitamin D levels as deficient (<12.5 ng·mL), insufficient (≥12.5 to <20 ng·mL), and sufficient (>20 ng·mL) and by CRF as unfit (lowest 20%) and fit (remaining 80%) based on age-standardized distribution of V˙O2max values in this study population. Body fatness, CRF, and metabolic risk factors were evaluated according to serum vitamin D classification. A clustered metabolic risk score was computed by summing standardized scores for waist circumference, resting blood pressures, triacylglycerols, the inverse of high-density lipoprotein cholesterol, glucose, and insulin. RESULTS Linear decreases in body fatness and metabolic risk factors were observed, as was a linear increase for CRF across incremental vitamin D categories. A linear decrease was found in the clustered metabolic risk score across incremental vitamin D categories. Compared to the fit group (reference), the unfit group had significantly higher risks for serum vitamin D inadequacy before and after adjusting for age, smoking, and body fatness parameters. CONCLUSIONS The findings of the study suggest that increasing vitamin D intake, eating a healthy diet, and getting enough outdoor physical activity should be promoted as nonpharmacologic means to improve CRF and prevent a clustering of metabolic risk factors in young adults.

The effect of physical activity on serum IL-6 and vaspin levels in late elementary school children.

[Purpose] This study investigates the effects of physical activity on serum IL-6 and vaspin in late elementary school children. [Methods] Those who (n = 220) completed the 7-day physical activity monitoring underwent a second round of measurements including body fat, serum glucose and insulin, and serum IL-6 and vaspin. One way ANOVAs followed by LSD post hoc tests were used to test for significant differences in dependent variables across incremental physical activity levels at p=0.05. Multivariate stepwise linear regression analyses were used to determine significant predictors for serum IL-6 and vaspin levels at p=0.05. [Results] The results showed significant inverse linear trends for body fat parameters across incremental physical activity levels (from low to high); the lower the body fat, the higher the physical activity levels. On the other hand, there were no significant linear trends for insulin resistance markers or dietary intake across incremental physical activity levels. Multiple stepwise linear regression analyses were used to determine significant predictors for individual variations in serum IL-6 and vaspin in the study population. We found that body mass index (p=0.002) and low- and moderate-intensity physical activities (p=0.002 and p=0.0045, respectively) were significant determinants of serum IL-6. In addition, low- and moderate-intensity physical activities (p=0.01 & p=0.022, respectively) were significant determinants of serum vaspin levels in this study population. [Conclusion] In summary, the findings of the current study suggest that promotion of physical activity along with a healthy diet should be key components of lifestyle interventions to improve serum cytokine profiles associated with insulin resistance syndrome in late elementary school children.

Serum Vitamin D status and its relations to body fatness and fitness and risk factors in young adults

The study examined the relations of serum vitamin D levels to body fatness, cardiorespiratory fitness (CRF), and metabolic risk factors in young adults in Korea. A total of 593 young men completed a health examination, body fatness, maximal treadmill exercise test, and assessment of metabolic risk factors. Participants were classified by serum vitamin D levels as deficient (< 20 ng/mL), insufficient (20~30 ng/mL), and sufficient (> 30 ng/mL). Body fatness, CRF, and metabolic risk factors were evaluated according to serum vitamin D classification. Significant inverse trends in body fatness and metabolic risk factors were observed, as was a significant linear trend for CRF across incremental vitamin D categories in this study population. Serum vitamin D levels were negatively associated with body fatness parameters, blood pressures, total cholesterol, triglycerides, and insulin and positively associated with high-density lipoprotein cholesterol and CRF. Compared to the BMI-based lean group, the obese groups had significantly higher odds ratio for serum vitamin D insufficiency before and after adjusting for age, CRF, and physical activity. Similarly, compared to percent body fat- and waist circumference-based lean groups, the obese groups had significant higher odds ratios for serum vitamin D insufficiency. In conclusion, the current findings of the study suggest that along with vitamin D intakes, body fat loss and outdoor physical activity should be promoted as non-pharmacologic means to improve metabolic risk factors in young adults.

The Relationship between Depressive Symptoms and Modifiable Lifestyle Risk Factors in Office Workers

Background This study investigated the relationship between depressive symptoms and physical fitness, obesity indices, and vitamin D status in office workers. Methods The subjects were 514 adults with more 30 years of experience as office workers in the city of Seoul. Lifestyle risk factors, obesity indices, physical fitness, and serum vitamin D levels were assessed with a standardized protocol. The Beck Depression Inventory (BDI) was used to assess depression status. Vitamin D status was assessed by measuring serum 25-hydroxyvitamin D concentrations. Based on the BDI scores, participants were classified into no depression (ND, BDI ≤9), mild depression (MiD, 10≤BDI≤15), and moderate depression (MoD, 16≤BDI≤23) groups. Results Compared with the high cardiorespriatory fitness group, the low cardiorespiratory fitness (men OR=2.618, women OR=1.596) an middle cardiorespiratory fitness group (men OR=1.256, women OR=1.110) had significantly higher odds ratio for having depressive symptoms, even after adjustment for age, hypertension, diabetes, hyperlipidemia, cardiovascular disease, alcohol intake, smoking, body mass index (BMI), percent body fat (%BF), and waist circumference (WC). Compared with the insufficient or deficient vitamin D group, the sufficient vitamin D group had significantly lower odds ratios for having depressive symptoms (men OR=0.121, women OR=0.114), even after adjustment for age, hypertension, diabetes, hyperlipidemia, cardiovascular disease, alcohol intake, smoking, BMI, %BF, and WC. Conclusion Vitamin D supplementation and outdoor activities should be key components of a lifestyle intervention against office workers’ depression.