Kijin Kim

Associations of visceral adiposity and exercise participation with C-reactive protein, insulin resistance, and endothelial dysfunction in Korean healthy adults

The aim of the current study was to examine the associations of visceral adiposity and exercise participation with C-reactive protein (CRP), insulin resistance, and endothelial dysfunction in Korean adults selected from the general population. We studied 160 Korean adults (aged 41.3 +/- 13.0 years; n = 38 men and n = 122 women) who volunteered in a health promotion program. Subjects were divided into 2 groups based upon spontaneous exercise participation for using a cross-sectional approach. We measured anthropometric factors (body mass index [BMI], percentage body fat, waist-hip ratio [WHR], and abdominal fat area by computed tomographic scanning), blood pressure (BP), blood levels of glucose, lipids, fibrinogen, CRP, leptin, hemoglobin A(1c), homeostasis model assessment (HOMA), and carotid intima media thickness (IMT; via ultrasonography). Associations among the variables were assessed by Pearson partial correlation and linear regression, controlling for age and sex. Independent t tests were used to assess differences between exercise participants and nonparticipants. Significance was accepted at P < .05. As expected, the measures of adiposity (BMI, percentage body fat, WHR, abdominal fat area) were highly correlated with each other (r = .49-.86, P < .01). Blood levels of high-sensitivity CRP (hsCRP), leptin, and HOMA were modestly correlated with all measures of adiposity. Visceral fat area was the most important predictor of hsCRP, explaining 19.6% of the variance using stepwise linear regression analysis (P < .01). As visceral fat area tertiles increased from low to high, a significant stepwise increment in blood levels of CRP (P < .001), HOMA (P = .005), and left carotid IMT (P = .035) was observed. However, hsCRP and HOMA were not significantly different when compared across whole-body fat tertiles. Systolic BP, diastolic BP, and left carotid IMT were modestly correlated with WHR and visceral fat area (P < .05); but systolic BP and diastolic BP were also correlated with BMI and percentage body fat (P < .05). Therefore, the relative importance of central adiposity as opposed to total body fatness in endothelial dysfunction is unclear. Compared with the nonexercise group, exercise participants had significantly lower (P < .05) WHR, visceral fat area, ratio of visceral fat area to subcutaneous area, hsCRP, hemoglobin A(1c), and HOMA, with no significant differences in BMI, percentage body fat, and physical fitness. Central obesity with high visceral fat is strongly associated with blood level of hsCRP, insulin resistance, and endothelial dysfunction-related factors in healthy Korean adults. In addition, exercise participation, even in the absence of difference in physical fitness, may be protective against development of central obesity and insulin resistance in this understudied Korean population.

Endurance exercise training reduces gallstone development in mice

Gallstones form when the ratio of bile cholesterol to bile acids and phospholipids is elevated, causing cholesterol to precipitate. Physical inactivity is hypothesized to increase gallstone development, but experimental evidence supporting this is lacking, and potential mechanisms for the antilithogenic effects of exercise have not been described. The purpose of this study was to examine the effect of endurance exercise training on gallstone formation and the expression of genes involved in bile cholesterol metabolism in gallstone-sensitive (C57L/J) mice. At 10 wk, 50 male mice began a lithogenic diet and were randomly assigned to an exercise-training (EX) or sedentary (SED) group (n = 25 per group). Mice in the EX group ran on a treadmill at approximately 15 m/min for 45 min/day for 12 wk. At the time animals were euthanized, gallstones were collected, pooled by group, and weighed. The weight of the gallstones was 2.5-fold greater in the SED mice compared with EX mice (143 vs. 57 mg, respectively). In the EX mice, hepatic expression of the low-density lipoprotein receptor (LDLr), scavenger receptor class B type 1 (SRB1), and sterol 27 hydroxylase (Cyp27) was increased by approximately 2-fold (P < 0.05 for each). The LDLr and SRB1 increase cholesterol clearance by low-density lipoprotein and high-density lipoprotein particles, respectively, while Cyp27 promotes the catabolism of cholesterol to bile acids. Taken together, these data indicate that exercise promotes changes in hepatic gene expression that increase cholesterol uptake by the liver but simultaneously increase the catabolism of cholesterol to bile acids, effectively reducing cholesterol saturation in the bile. This suggests a mechanism by which exercise improves cholesterol clearance from the circulation while simultaneously inhibiting gallstone formation.

Effects of an elastic band resistance exercise program on lower extremity muscle strength and gait ability in patients with Alzheimer’s disease

[Purpose] This study examined the effects of a resistance exercise programs aiming to improve muscular function in order to prevent and treat Alzheimer’s disease in elderly people. [Subjects and Methods] Elderly patients with mild dementia were randomly assigned to an elastic band resistance exercise group (74.21±6.09 years). The experimental group (n=23) performed upper and lower extremity exercises three times per week for five months. Physical fitness was measured according to chair leg squat, one-leg stance, timed up-and-go test, 2-minute walking test, and gait ability before and after exercise. [Results] Static balance ability in which the participant stood on one foot with eyes open (left and right) increased significantly, but the dynamic balancing ability in the timed up-and-go test did not improve significantly. Cardiorespiratory function and gait speed improved significantly. [Conclusion] The five-month elastic band resistance exercise program improved muscle strength and endurance, cardiovascular function, and gait speed. Therefore, it may be an effective rehabilitation program for elderly patients with Alzheimer’s disease.

Effects of Cold Environment Exposure and Cold Acclimatization on Exercise-Induced Salivary Cortisol Response

Abstract Objective.—Considering the adverse effects of exercise-induced cortisol secretion on health in athletes, it is important to determine the environmental and individual factors that contribute to the variations in exercise-induced cortisol secretion. In this study, the effects of cold environment exposure and cold acclimatization on exercise-induced salivary cortisol responses were investigated. Methods.—Short track skaters (n  =  11), who usually practice under cold conditions, and inline skaters (n  =  11), who usually practice under room temperature conditions, participated in a randomized crossover study. All participants cycled for 60 minutes at 65% V˙o2 max under cold (ambient temperature: 5 ± 1°C, relative humidity 41% ± 9%) and room temperature (ambient temperature: 21 ± 1°C, relative humidity 35% ± 5%) conditions. The participants had a 120-minute bed rest recovery phase at room temperature after both exercise bouts. Cortisol levels were measured in saliva samples collected pre-exercise and postexercise at 1 minute, 30 minutes, 60 minutes, and 120 minutes. Results.—Both short track and inline skaters exhibited clear cortisol responses to exercise under cold and room temperature conditions. The magnitude of the cortisol response, however, was different between skaters and conditions. The inline skaters exhibited significantly higher cortisol values under cold conditions than under room temperature conditions (7.6 nmol/L and 4.2 nmol/L, respectively). However, the short track skaters exhibited significantly higher cortisol values under cold conditions compared to room temperature conditions (8.7 nmol/L and 5.4 nmol/L, respectively). Conclusions.—The effects of cold environment exposure on exercise-induced cortisol response were different between skaters who usually practice under cold or room temperature conditions. These results can be interpreted as acclimatization to either cold or room temperature conditions attenuating the cortisol response, suggesting that acclimatization may be beneficial in reducing the exercise-induced cortisol response.

Exercise-induced PGC-1α transcriptional factors in skeletal muscle

Skeletal muscle is adapting to the needs of the body by changes of various gene expression that control mitochondrial biogenesis, angiogenesis, and the composition of muscle fiber types. Recently, it was revealed that PGC-1α, which is an auxiliary transcription factor, plays a key role in the aforementioned adaptation phenomena. It means that various signal transduction systems within muscle directly affect the expression and activation of PGC-1α and also PGC-1s activates various programs for muscle adaptation. Therefore, this review assessed PGC-1α to understand the reaction and adaptation phenomena of muscle against the biological stimulus such as exercise and came to the conclusion that PGC-1α and PGC-1β significantly affect skeletal muscle in various ways, and also have an affect on the increase of exercise capacity, inducing of angiogenesis and the prevention of muscle atrophy and degeneration.

PHYSIOLOGICAL AND LEUKOCYTE SUBSET RESPONSES TO EXERCISE AND COLD EXPOSURE IN COLD-ACCLIMATIZED SKATERS

We investigated physiological responses and changes in circulating immune cells following exercise in cold and thermoneutral conditions. Participants were short track skaters (n=9) who were acclimatized to cold conditions, and inline skaters (n=10) who were not acclimatized. All skaters were young, and skating at a recreational level three days per week for at least one year. Using a cross-over design, study variables were measured during 60 min of submaximal cycling (65% V.O2max) in cold (ambient temperature: 5±1°C, relative humidity: 41±9%) and thermoneutral conditions (ambient temperature: 21±1°C, relative humidity: 35±5%). Heart rate, blood lactate and tympanic temperature were measured at rest, during exercise and recovery. Plasma cortisol, calprotectin and circulating blood cell numbers were measured before and after 60 min of cold or thermoneutral conditions, and during recovery from exercise. Heart rate was lower in both groups during exercise in cold versus thermoneutral conditions (P<0.05). The increase in total leukocytes during recovery was primarily due to an increase in neutrophils in both groups. The cold-acclimatized group activated neutrophils after exercise in cold exposure, whereas the non-acclimatized group activated lymphocyte and cortisol after exercise in cold exposure. Lymphocyte subsets significantly changed in both groups over time during recovery as compared to rest. Immediately after exercise in both groups, CD16+ and CD69+ cells were elevated compared to rest or before exercise in both conditions. Acclimatization to exercise in the cold does not appear to influence exercise-induced immune changes in cold conditions, with the possible exception of neutrophils, lymphocytes and cortisol concentration.

Effects of exercise and diet composition on expression of MCP-1 and oxidative stress-related mRNA of adipose tissue in diet-induced obese mice

The aim of the study was to analyze how the expression of MCP-1, HIF-1α, NOX2, ERK1, ERK2, and Mn-SOD mRNA, which are related to inflammation and oxidative stress and which can influence the accumulation of macrophage in obese adipose tissue, differed according to a high-fat diet, change of diet composition, and exercise. Obesity was induced using a high-fat diet (45% fat) for five weeks. This investigation analyzed how the change of diet composition for eight weeks and long-term exercise training affected the expression of mRNA in epididymal white adipose tissue. For the experiment, 56 four-week-old C57BL/6 mice were used. Their epididymal white adipose tissue was extracted and used in RT-PCR analysis to find the expression level of mRNA. A high-fat diet for 13 weeks showed a significant increase in the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA in epididymal adipose tissue. Change in diet composition and exercise decreased the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA. Particularly, the group combining a high-fat diet and exercise had a significant increase in the expression of Mn-SOD mRNA in epididymal adipose tissue; however, it showed a significant decrease in MCP-1, HIF-1α, and NOX2. These results suggest that the antioxidant effect and weight loss by exercise decreased inflammation and oxidative stress.

High-density lipoprotein cholesterol (HDL-C) in cardiovascular disease: effect of exercise training

Decreases in high-density lipoprotein cholesterol (HDL-C) levels are associated with an increased risk of coronary artery disease (CAD), whereas increased HDL-C levels are related to a decreased risk of CAD and myocardial infarction. Although HDL prevents the oxidation of low-density lipoprotein under normal conditions, it triggers a structural change, inhibiting antiarteriosclerotic and anti-inflammatory functions, under pathological conditions such as oxidative stress, inflammation, and diabetes. HDL can transform into various structures based on the quantitative reduction and deformation of apolipoprotein A1 and is the primary cause of increased levels of dysfunctional HDL, which can lead to an increased risk of CAD. Therefore, analyzing the structure and components of HDL rather than HDL-C after the application of an exercise training program may be useful for understanding the effects of HDL.

Effect of Taekwondo Training on Physical Fitness and Growth Index According to IGF-1 Gene Polymorphism in Children.

This study analyzed the effect of regular Taekwondo training for 16 weeks on physical fitness and growth index depending on different IGF-1 gene polymorphisms. The subjects of the study were 44 male students who were 8 year years old. The IGF-1 gene showed the highest frequency of 18 CA repeat (190 bp) in 50% of subjects, and was found in the homozygote (n=11), heterozygote (n=22) and non-carriers (n=11). The results of the physical fitness and growth index among the gene polymorphism groups indicated no significant differences but the expected height of the non-carrier group was significantly high (p<0.05). After Taekwondo training, the homozygote group and the non-carrier groups demonstrated significant (p<0.05) increase in grip strength and in time in the standing with one leg while closing eyes test, respectively. Only the homozygote group had a significant (p< 0.05) increase in thigh circumference. IGF-1 concentration significantly (p<0.05) increased in the heterozygote group, while HOMA-IR significantly (p<0.05) decreased in the homozygote group. Furthermore, there was a significant (p<0.05) decrease in glucose in both the homozygote and the non-carriers groups. The difference between physical fitness and growth index depending on the IGF-1 gene polymorphism after Taekwondo training did not show consistent impact.

Combined influence of dietary restriction and treadmill running on MCP-1 and the expression of oxidative stress-related mRNA in the adipose tissue in obese mice.

[Purpose] This study suggests that the negative effects of inflammation caused by obesity could be prevented through diet restriction and exercise. [Methods] In this study, 44 C57/BL6 male mice at about 4 weeks old (Orient bio, South Korea) were given a high fat diet for 5 weeks to make them obese. To help the mice lose weight, their dietary intake was limited and they were exercised on the treadmill for 8 weeks, and during that period, we analyzed the changes of MCP-1, ERK, Mn-SOD, HIF-1, and NOX in epididymal adipose tissue. There ND control group and obese group with high fat diet (HFD), and it is divided into four groups; HFD-ND-EX group, HFD-ND-nonEX group, HFD-DR-EX group and HFD-DR-nonEX group. [Results] During their progress, the mRNA expressions of HIF-1α and ERK2 decreased, as did the expression of MCP-1 contained in the nucleus by suppressing oxygen free radicals, which was observed after the exercise program. However, dietary restriction without exercise training triggered an increase in the mRNA expression of MCP-1. [Conclusion] To put this in perspective, combining exercise and dietary intake restriction likely prevented an influx of macrophages by reducing the number of fat cells, whereas only dietary restriction was not effective against reducing inflammation.