Ju Yong Bae

Exercise Training Improves Cardiac Autonomic Nervous System Activity in Type 1 Diabetic Children

[Purpose] We investigated the effect exercise training has on cardiac autonomic nervous system (ANS) and cardiovascular risk profiles in children with type 1 diabetes mellitus (DM). [Subjects] Fifteen type 1 DM children (all boys; 13.0±1.0 years of age) were enrolled in the study. [Methods] The subjects received exercise training three times a week in a 12-week program. Each child was asked to walk on a treadmill to achieve an exercise intensity of VO2max 60%. ANS activity was measured by power spectral analysis of the electrocardiogram (ECG). Blood samples were obtained for serum lipid profiles. To evaluate Doppler-shifted Fourier pulsatility index (PI) analysis, a 5-MHz continuous wave Doppler (VASCULAB D10) set was used to measure forward blood flow velocity (FLOW) in the radial artery. [Results] Total and low-frequency (LF) power of heart rate variability increased significantly after exercise intervention. Total cholesterol (TC) levels were significant lower after exercise intervention. Total and high-frequency (HF) power were significantly correlated with higher TC levels, but diastolic blood pressure and HF was significantly correlated with lower TC levels. [Conclusion] Regular exercise intervention should be prescribed for children with type 1 DM.

The effects of detraining and training on adipose tissue lipid droplet in obese mice after chronic high-fat diet

BackgroundIt is well known that exercise promotes lipolysis by stimulating the lipid droplet (LD) signaling pathway. However, few studies have been conducted to examine the effect of detraining with high fat diet (HFD) and training effects after long-term HFD. Here, we investigated the effect of detraining and training on adipose tissue LD pathway in diet-induced obese mice after continuous HFD.MethodsSeventy male C57BL/6 mice were randomly assigned into a Normal diet + Sedentary group (ND, n = 10) or a High-fat diet + Sedentary group (HF, n = 50); in the HF group, obesity was induced by a 45% fat chow for six weeks. For the subsequent eight weeks, the HF group was randomly subdivided into an HF (n = 30) or an HF + training group (HFT, n = 20), and the HFT group was subjected to treadmill training while on an HFD. Following this eight-week period, the HFT group stopped exercising (HFT-DT group, n = 10), and the mice in the HF group were randomly subdivided into an HF (n = 10) or an HF + training group (HF-T, n = 10). After training and detraining, abdominal visceral fat was obtained and analyzed by histological staining and western blot.ResultsTreadmill exercise decreased body weight and fat mass (P <0.05), and increased the levels of PKA, perilipin1, CGI-58, ATGL, and HSL (P <0.05) after eight weeks of training. Following eight weeks of detraining, the levels of PKA and HSL were decreased (P <0.05); however, exercise after chronic HFD increased the levels of PKA, perilipin1, CGI-58, ATGL, and HSL (P <0.05), and decreased body weight and fat mass (P <0.05).ConclusionsRegardless of dietary restrictions, exercise is an effective treatment for obesity, owing to the regulation of LD signaling proteins. Moreover, the effects of regular exercise after chronic HFD were similar to those of exercise in the absence of HFD. Therefore, although obesity is induced by chronic HFD, exercise without dietary change is sufficiently effective for obesity treatment regardless of the preceding HFD period.

Exercise and dietary change ameliorate high fat diet induced obesity and insulin resistance via mTOR signaling pathway

[Purpose] The purpose of this study was to investigate the effect of exercise and dietary change on obesity and insulin resistance and mTOR signaling protein levels in skeletal muscles of obese rats. [Methods] Sixty male Sprague-Dawley rats were divided into CO (Normal diet) and HF (High Fat diet) groups in order to induce obesity for 15 weeks. The rats were then subdivided into CO, COT (CO + Training), HF, HFT (HF + Training), HFND (Dietary change), and HFNDT (HFND + Training) groups (10 rats / group). The training groups underwent moderate-intensity treadmill exercise for 8 weeks, after which soleus muscles were excised and analyzed. Data was statistically analyzed by independent t-test and One-way ANOVA tests with a 0.05 significance level. [Results] Fasting blood glucose, plasma insulin, and HOMA-IR in the HF group were significantly higher, as compared with other groups (p <.05). Protein levels of insulin receptor subunit-1 (IRS-1), IRS-2, and p-Akt were significantly higher in the HFT, HFND, and HFNDT groups, as compared with HF group. In addition, the protein levels of the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal S6 protein kinase 1 were significantly decreased by exercise and dietary change (p <.05). However, mTORC2 and phosphoinositide 3-kinase were significantly increased (p <.05). [Conclusion] In summary, despite the negative impact of continuous high fat intake, regular exercise and dietary change showed a positive effect on insulin resistance and mTOR signaling protein levels.

The effect of exercise on expression of myokine and angiogenesis mRNA in skeletal muscle of high fat diet induced obese rat.

[Purpose] The purpose of this study was to investigate the effect of regular treadmill exercise on the mRNA expressions of myokines and angiogenesis factors in the skeletal muscle of obese rats. [Methods] Thirty two male Sprague-Dawley rats (4weeks old) were divided into the CO (control) and HF (high fat diet) groups. Obesity was induced in the HF group by consumption of 45% high-fat diet for 15 weeks. These groups were further subdivided into training groups (COT and HFT); the training groups conducted moderate intensity treadmill training for 8 weeks. Soleus muscles were excised and analyzed by real-time quantitative PCR. [Results] mRNA expression of myokines, such as PGC-1α, IL-6, and IL-15, in the COT and HFT groups (which conducted regular exercise), were higher as compared with the CO and HF groups (p < 0.05). Also, the levels in the HF group were significantly lower when compared with CO group (p < 0.05). Expression of angiogenesis mRNA, namely mTOR, VEGF, and FLT1, were significantly lower in the HF group, as compared to the CO group (p < 0.05). In addition, COT group had a higher expression of mTORC1, mTORC2, VEGF and FLT mRNA, than the CO group (p < 0.05); the HFT group also had higher expressions of mTOR, VEGF and FLT1 mRNA than the HF group (p < 0.05). [Conclusion] These results indicate that mRNA expression of myokines was increased through the activity of muscle contraction, and it also promoted the mRNA expression of angiogenesis due to activation of mTOR. Thus, we conclude that not only under normal health conditions, but in obesity and excess nutritional circumstances also, regular exercise seems to act positively on the glycemic control and insulin sensitivity through the angiogenesis signaling pathway.

Correlation between basic physical fitness and pulmonary function in Korean children and adolescents: a cross-sectional survey.

[Purpose] The purpose of the present study was to determine whether there was a correlation between basic physical fitness and pulmonary function in Korean school students, to present an alternative method for improving their pulmonary function. [Subjects and Methods] Two hundred forty healthy students aged 6–17 years performed physical fitness tests of hand-grip strength, sit and reach, Sargent jump, single leg stance, and pulmonary function tests of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) using a Quark PFT. [Results] Muscle strength and power of boys improved in the late period of elementary school and middle school. Muscle strength of girls improved in the late period of elementary school. Analysis of factors affecting pulmonary function revealed that height, weight, BMI, and body fat significantly correlated with spirometric parameters. Right hand-grip strength, left hand-grip strength, and Sargent jump also significantly correlated with FVC and FEV1. [Conclusion] In order to improve the pulmonary function of children and adolescents, aerobic exercise and an exercise program to increase muscle strength and power is needed, and it should start in the late period of elementary school when muscle strength and power are rapidly increasing.

Effects of treadmill exercise on skeletal muscle mTOR signaling pathway in high-fat diet-induced obese mice.

[Purpose] The aim of this study was to investigate the effects of regular treadmill exercise on skeletal muscle Rictor-Akt and mTOR-Raptor-S6K1 signaling pathway in high-fat diet-induced obese mice. [Subjects and Methods] Four- week-old C57BL/6 mice were adopted and classified into normal diet group (ND, n = 10), normal diet and training group (NDT, n = 10), high-fat diet group (HF, n = 10), and high-fat diet and training group (HFT, n = 10). The exercise program consisted of a treadmill exercise provided at low intensity for 1–4 weeks, and moderate intensity for 5–8 weeks. [Results] The Western blot method was used to measure the expression of mTOR, Raptor, S6K1, Rictor, and Akt proteins in the soleus muscle. mTOR levels were significantly higher in the HF group than in the ND and NDT groups. Raptor/mTORC1 and S6K1 levels were significantly higher in the HF group than in all the other groups. Akt levels were significantly lower in the HF group than in the NDT group. The risk of obesity may be associated with the overactivation of the mTOR-Raptor-S6K1 signaling pathway and a decrease in Akt levels. [Conclusion] This study also indicates that performing aerobic exercise may be associated with the downregulation of the mTOR-Raptor-S6K1 pathway.

Brain function factors after high acceleration exposure in Korea Air Force cadets

Fighter pilots perform a variety of physical activities to improve and maintain their fitness, but there is a lack of research on brain function factors for high acceleration exposure. Therefore, the aim of this study was to investigate the differences of physical fitness between success and failure group, and to examine the changes in blood brain function factors after exposure to high acceleration condition. Air force cadets were participated and divided into the success (n=38), failure within 10 s (failure group A, n=19), failure within 20 s (failure group B, n=10) and failure within 30 s (failure group C, n=12) groups after conducting G-tolerance test. In terms of muscle mass, the failure group C showed significantly higher values than the failure group A (p<0.05). In the sit-up test, the success group showed significantly higher values than the failure group D (p<0.05). BDNF and CTSB levels were significantly increased in the success group and the failure group D after acceleration exposure (p<0.05). As can be seen from the results of this study, high acceleration exposure caused a significant increase in the CTSB level in the success group that is considered to be the result of high strength isometric movement of the human body to withstand high pressure. Therefore, the results of this study suggested that to improve muscle strength is essential to withstand high acceleration conditions.

Effects of combined open kinetic chain and closed kinetic chain training using pulley exercise machines on muscle strength and angiogenesis factors.

[Purpose] This study investigated the effects of combined open kinetic chain and closed kinetic chain training using pulley exercise machines on muscle strength, anaerobic power, and blood levels of angiogenesis factors. [Subjects and Methods] Twenty male university students were equally divided between control and pulley training groups. The pulley-training group underwent 8 weeks of combined training. Open kinetic chain training consisted of 2 sets of 10 repetitions at 60% of one repetition maximum; closed kinetic chain training consisted of 2 sets of 10 repetitions of resistance exercise using the subject’s own body weight. Isokinetic strength (trunk and knee), anaerobic power, vascular endothelial growth factor, angiopoietin-1, angiopoietin-2, and follistatin were analyzed. [Results] After 8 weeks, flexor and extensor muscle strength significantly increased in the trunk and knee; average and peak power also increased significantly. Angiopoietin 1 increased 25% in the control group and 48% in the pulley training group; vascular endothelial growth factor and follistatin increased significantly in the pulley-training group after 8 weeks. [Conclusion] Eight weeks of combined training using pulley exercise machines effectively increased biochemical factors related to muscle growth, as well as muscle strength in the trunk and knees.