Comparison of association between physical activity and resting metabolic rate in young and middleaged Korean adults

( Hyejung Hwang ),( Won-sang Jung ),( Jisu Kim ),( Hun-young Park ),( Kiwon Lim ) 한국운동영양학회 2019 Physical Activity and Nutrition (Phys Act Nutr) Vol.23 No.2

[Purpose] The purpose of this study was to comparatively investigate the correlation among body composition, resting metabolic rate (RMR), and physical activity (PA) between young and middle-aged Korean adults. [Methods] A total of 53 [male n=23, female n=30] subjects were included in this study, among whom 34 subjects were healthy young adults [male n=18, female n=16] and 19 were middle-aged adults [male n=5, female n=14]. The body composition and RMR of all the participants were measured after overnight fasting (≥8 h). The Korean version of the WHO Global Physical Activity Questionnaire (GPAQ) was used to assess physical activity. [Results] Body composition was not significantly different between young adults and middle-aged adults. Whole-body bone mineral density and bone mineral contents (BMC) were significantly lower in middle-aged adults than in young adults. Total blood cholesterol (TC) and blood glucose levels were significantly higher in middle-aged adults (TC; 195.21 ± 43.34, glucose; 103.57 ± 12.61 mg/dL) than in young adults. RMR was significantly lower in middle-aged adults (1619.57 ± 290.28 kcal/day) than in young adults (1894.37 ± 405.00 kcal/day). In middle-aged adults physical activity (PA). PA (METs, min, EE) was inversely correlated with fat mass (FM, kg, and %) and blood triglyceride (TG) level in young adults. In middle-aged adults, PA showed a significant positive correlation with lean body mass (LBM), FM (%), and RMR. Furthermore, PA EE showed significant interrelatedness with BMC among middle-aged adults. [Conclusion] These results demonstrated that high PA levels enable LBM and RMR maintenance in middle- aged adults. Furthermore, in young adults, more PA is required to induce change in body composition.

The effects of red ginseng intake on central and peripheral fatigue in non-trained and trained mice

( Hyejung Hwang ) 한국체육학회 2015 전국체전기념 한국체육학회 학술발표회 Vol.2015 No.-

Exercise training is a process of enhancing one’s performance level by using the adaptability of the body towards certain exercise stimulus. Fatigue is an inevitable physiological phenomenon that develops in accordance with training that is caused by the peripheral and central nervous systems. Fatigue is mainly divided into central nervous system fatigue, which the cerebrum perceives, and peripheral fatigue, which occurs in muscle and nerve tissues. There are a few natural substances that are so-called adaptogen in Korea, including Korean ginseng and red ginseng (RG), as well as otherfamiliar medicinal herbs. Ginsenoside (Rg1, Rb1, Rg2, etc.) is known to be the main ingredient that shows such effects in RG. Also, it has been found to have beneficial effects on physical and brain activity. This study aims to analyze energy utilization from RG administration alone and from the combination of RG administration and exercise, and to investigate the mechanism and the effect of RG administration on exercise-induced fatigue by analyzing 5-HT mRNAs, a central nervous system fatigue factor that is induced during pre-exercise, post-exercise, and recovery, energy utilization during resting and exercise (a peripheral fatigue factor), and glycogen contents in tissues and change in proteins related to energy control through 2 weeks intervention of RG and treadmill training in an animal model. In study 1, the resting metabolic rate was measured for 24 hours before and after the 2 week experimental periods. The total amount of food intake was significantly higher in the RG group than in the control group (CON) (p<0.05), whereas mean body weight was the same. Oxygen uptake during 24 hours both before and after the experimental session was the same between the two groups. Resting carbohydrate oxidation and fat oxidation were the same between the two groups. Likewise, there was no difference in the expression of mRNAs related to energy substrate utilization in skeletal muscle (gastrocnemius) between the groups. Accordingly, we suggest that for the administration of red ginseng at rest to be more effective, a follow-up study (Study 2) was needed as the administration of RG at rest was different from that during exercise. In study 2, the neurotransmitter associated with central fatigue, TPH and 5-HTT mRNAs appeared to be not significantly different in the brain. And, in the RG group with treadmill exercise training (RG-Tr), the expression of 5-HTT and 5-HT1A and 5-HT2A m RNA in the hypothalamus, dorsal raphe and hippocampus were lower compared to the CON-Tr group. The inhibition of expression of 5-HTT and the 5-HT receptors (5-HT1A and 5-HT2A) was shown to be effective on fatigue caused by exercise. However, in this study brain analysis showed only a tendency, not a significant difference, which was caused by the limited number of analyzed subjects (n=3). The changes in energy utilization parameters associated with peripheral fatigue, and the resting metabolic rate for 24 hours were measured before and after the 2 week experimental periods. There was no change in resting metabolism between the CON-Tr and RG-Tr groups. However, the increased fat oxidation occurred after the initial 20 min of the 1 hour exercise period. Also it significantly saved glycogen in the liver. The glycogen saving effect tended to increase in white gastrocnemius after the 2 week training, immediately after 1 hour of exercise. Nevertheless, there were no changes in related expression of mRNA related to carbohydrate or fat metabolism in the gastrocnemius muscle. In conclusion, sole intake of RG did not induce any noticeable effect on resting (study 1). However, RG intake did have an effect on the response to body’s changing conditions from exercise, which induces strenuous impact to body like disruptive homeostasis and induced exercise stress. Therefore, the results of our study taken together, show that the intake of RG is an effective ergogenic aid in improving endurance exercise. From this study, it is seen that further research on finding a supplement (ergogenic aids) that helps improve exercise ability is required.

Muscle oxygenation, endocrine and metabolic regulation during lowintensity endurance exercise with blood flow restriction

( Hyejung Hwang ),( Sahiro Mizuno ),( Nobukazu Kasai ),( Chihiro Kojima ),( Daichi Sumi ),( Nanako Hayashi ),( Kazushige Goto ) 한국운동영양학회 2020 Physical Activity and Nutrition (Phys Act Nutr) Vol.24 No.2

[Purpose] The present study investigated the effect of endurance exercise with blood flow restriction (BFR) performed at either 25% maximal oxygen uptake (V3 O2 max) or 40% V3 O2 max) on muscle oxygenation, energy metabolism, and endocrine responses. [Methods] Ten males were recruited in the present study. The subjects performed three trials: (1) endurance exercise at 40% V3 O2 max without BFR (NBFR40), (2) endurance exercise at 25% V3 O2 max with BFR (BFR25), and (3) endurance exercise at 40% V3 O2 max with BFR (BFR40). The exercises were performed for 15 min during which the pedaling frequency was set at 70 rpm. In BFR25 and BFR40, 2 min of pressure phase (equivalent to 160 mmHg) followed by 1 min of release phase were repeated five times (5 × 3 min) throughout 15 minutes of exercise. During exercise, muscle oxygenation and concentration of respiratory gases were measured. The blood samples were collected before exercise, immediately after 15 min of exercise, and at 15, 30, and 60 minutes after completion of exercise. [Results] Deoxygenated hemoglobin (deoxy-Hb) level during exercise was significantly higher with BFR25 and BFR40 than that with NBFR40. BFR40 showed significantly higher total-hemoglobin (total-Hb) than NBFR40 during 2 min of pressure phase. Moreover, exercise-induced lactate elevation and pH reduction were significantly augmented in BFR40, with concomitant increase in serum cortisol concentration after exercise. Carbohydrate (CHO) oxidation was significantly higher with BFR40 than that with NBFR40 and BFR25, whereas fat oxidation was lower with BFR40. [Conclusion] Deoxy-Hb and total Hb levels were significantly increased during 15 min of pedaling exercise in BFR25 and BFR40, indicating augmented local hypoxia and blood volume (blood perfusion) in the muscle. Moreover, low-and moderate-intensity exercise with BFR facilitated CHO oxidation.

The Comparisons of Children's Emotional and Behavioral Problems and the Roles of Grandparents in Nuclear and Extended Families

Hwang, Hyejung 대한가정학회 2003 Human Ecology Research(HER) Vol.41 No.12

본 연구에서는 핵가족과 확대가족의 구조가 한국 초등학교 아동의 문제행동에 미치는 영향을 비교하였다. 서울과 인천에 거주하는 417명의 초등학생을 대상으로 그들의 문제행동을 Chidren's Behaviour Questionnair(CBQ: Rutter, 1967)에 의해서 교사가 평가하였으며, 아동은 그들 조부모의 역할을 Grandmother's Role Questionnair(GRQ: Suh, 1991)에 의해서 평가하였다. 그 결과, 확대가족의 아동은 핵가족의 아동보다 문제행동을 덜 보였으며, 확대가족의 조부모가 손자녀를 정서적으로 지지하고 돌보아주며 생활에 간섭하는 역할을 하는 반면에 핵가족의 조부모는 손자녀를 훈계하는 역할을 주로 하는 것으로 나타났다. 즉, 확대가족에서의 조부모는 손자녀의 정서적인 안정을 뒷받침하고 또한 부모의 스트레스를 완화시키며 가족의 화목한 분위기를 증진시키는 등의 역할을 통해서 손자녀에게 직접적, 간접적으로 영향을 미치며, 이러한 조부모의 역할은 아동의 문제행동에 근간이 되는 가족의 역동성에 영향을 미친다고 본다.

Effects of Endurance Training for 4weeks on Resting Metabolic Rate and Energy Metabolism During Exercise in Mouse

Hyejung Hwang,Jisu Kim,Yerim Jeon,Kiwon Lim 한국식품영양과학회 2012 한국식품영양과학회 학술대회발표집 Vol.2012 No.10

유·초등 연계교육에 대한 우리나라와 미국의 유아교사와 초등교사의 인식 비교

황혜정(Hyejung Hwang) 한국열린교육학회 2009 열린교육연구 Vol.17 No.1

본 연구에서는 유초등 연계교육에 대한 우리나라와 미국 교사의 인식차이를 알아보고, 우리나라와 미국 각각에서 학교급에 따른 교사의 인시에도 차이가 있었는지를 알아보고자 하였다. 연구의 대상은 우리나라와 미국의 유치원과 초등학교에 재직 중인 833명의 교사들이었다. 유초등 연계교육에 대해 작성한 질문지를 사용하여 이들의 인식을 조사하고, 이를 차이검증 하였다. 연구결과, 첫째, 우리나라 유치원 교사에 비해 미국 유치원 교사가 유초등 연계교육에 대해 더 잘 인식하고 있었다. 둘째, 유초등 연계교육에 관한 대부분의 문항에서 우리나라 초등학교 교사와 미국 초등학교 교사의 인식 간의 유의한 차이가 없었다. 셋째, 우리나라 초등학교 교사가 유치원 교사보다 유초등 연계교육에 대해서 더 잘 알고 있다고 인식하고 있으며, 병설유치원 교사는 사립유치원 교사보다 초등학교 교사와 그 인식이 더 유사하였다. 넷째, 미국의 경우 유치원교사와 초등학교 교사의 인식에는 유의한 차이가 거의 없었다. 본 연구는 공교육화가 교사의 인식에 미치는 영향을 살펴보고 연계교육을 위한 실질적인 실천방안을 마련하는데 기초자료를 제공하고자 한다. The purpose of this research was to compare the kindergarten and elementary school teacher's perceptions on the continuity of early childhood and primary education in Korea and USA. The subjects were 833 kindergarten and elementary school teachers. The instrument used in this study was questionnaire developed concerning the perceptions on educational continuity, and the data were analyzed using t and F tests. The results of this study were summarized as follows: First, the US kindergarten teachers showed higher degrees of perception in knowing the definition, aims, necessity, and practice of the educational continuity and the curriculum of the counterpart than Korean kindergarten teachers. Second, there was no significant difference in the perceptions of the Korean and the US elementary school teachers in most areas. Third, in Korea, elementary school teachers showed higher degrees of perception in knowing the definition, aims, and practice of the educational continuity and the curriculum of the counterpart than kindergarten teachers. Fourth, there was no significant difference in the perceptions of the kindergarten and the elementary school teachers in USA. These results imply that teachers' perceptions on the educational continuity between kindergarten and elementary school can be enhanced by formalizing early childhood education.

5주간의 고지방식이 섭취시 흰쥐의 에너지 대사 기질 이용과 식이지방에너지 평가에 관한 연구

황혜정(Hyejung Hwang),김지수(Jisu Kim),서혜정(Heajung Suh),임기원(Kiwon Lim) 한국식품영양과학회 2012 한국식품영양과학회지 Vol.41 No.8

This study investigated the effect of a long-term high-fat diet on energy metabolic substrate utilization in resting rats in order to revalue source fat energy efficiency during a high-fat diet and its effect on energy expenditure and body fat accumulation. Sprague-Dawley male rats at 4 weeks of age were bought from Orient Bio Con. The rats were divided into a control (CON) group and a high-fat diet (HF) group. Rats ate a high-fat diet (w/w 40%, kcal/kcal 64.9%) ad libitum for 5 weeks. Food intake and body weight were measured every day at 09:00 throughout the experimental period. Energy expenditure was measured using an animal energy metabolism chamber after 4 weeks. The final body weight did not change between the CON and HF groups, but caloric intake was significantly higher in the HF group than in the CON group (p<0.05). There was no difference between the groups in oxygen uptake, however carbon dioxide production was significantly higher in the HF group. Also, the respiratory exchange ratio was higher in the HF group. Carbohydrate oxidation was lower in the HF group than in the CON group, but fat oxidation in the HF group was greater. These results mean that energy substrate oxidation at rest is affected by diet composition, especially dietary fat content. Abdominal fat fad weights were significantly higher by 33% in the HF group than in the CON group even though the calorie intake in the HF group was higher by 6%. These results suggested that the dietary fat calorie value might have a higher Atwater value of 9 kcal/g, which mean that dietary fat calorie values could be reconsidered in body weight control scenarios such as which the obese or weight class athletes.

영아의 기본생활습관에 대한 영아 변인과 부모 변인의 상대적 영향력 연구

황혜정(Hwang, Hyejung) 한국영유아보육학회 2016 한국영유아보육학 Vol.0 No.98

본 연구는 육아정책연구소의 2차년도 한국아동패널 자료를 이용하여 영아의 기본생활습관에 미치는 영아 변인과 부모 변인의 상대적 영향력을 비교하였다. 연구대상은 12~18개월 영아 2,150명이었다. 영아 변인(성, 기질, 발달 특성)과 부모 변인(어머니의 취업 여부, 양육행동, 양육스트레스, 자아존중감, 아버지의 자녀양육 참여, 월 소득)을 독립변인으로 하고 영아의 월령을 통제하여 중다회귀분석을 실시하였다. 연구결과, 이들 변인 중 영아변인에서는 발달 특성(개인-사회성, 의사소통, 문제해결, 대근육운동), 성 및 활동성 기질, 부모 변인에서는 어머니의 온정적 양육행동과 자아존중감, 아버지의 자녀양육 참여가 영아의 기본생활습관에 영향을 미쳤으며, 이들의 설명변량은 21.1%였다. This study was performed using the 2nd Panel study on Korean children. The purpose of this study was to compare the effects of infants’ and parental variables affecting infants’ basic daily life habits. The subjects of this study were 2,150 one year-olds. The data were analyzed by multiple regression. The results were as follows: The variables which had significant effects on infants’ basic daily life habits were infants’ developments in personal-social, communication, problem solving and gross motor movement domains, temperaments and gender, mothers’ affective child-rearing behaviors and self-esteem, and fathers’ helps in child-rearing. And these variables explained 21.1% of infants’ basic daily life habits.

The Effects of Family Structures on Children's Emotional and Behavioural Problems

황혜정 경기대학교 2000 論文集 Vol.44 No.1

본 연구에서는 핵가족과 확대가족의 구조가 한국 초등학교 아동의 문제행동에 미치는 영향을 비교하였다. 연구 1에서는 650명 아동의 문제행동이 Children's Behaviour Questionnaire (Rutter, 1967)로 교사에 의해서 평가되었다. 그 결과, 확대가족의 아동은 핵가족의 아동보다 문제행동을 덜 보였다. 연구 1의 결과에 기초하여 연구 2에서는 부모의 양육태도와 가정에서의 학습준비가 아동의 문제행동에 영향을 미치는 매개 변인으로 고려되었다. 연구 2의 대상은 417명의 새로운 아동과 연구 1에서 추적된 175명의 아동이었다. 부모의 양육태도는 Parental Acceptance-Rejection Questionnaire (Rohner, 1984)에 의해서 평가되었으며, 가정에서의 학습준비는 Child's Activities Diary (연구자 제작)에 의해서 측정되었다. 연구 2의 결과에 의하면, 핵가족과 확대가족 아동의 문제행동의 차이는 부모의 양육태도의 차이와 가정에서의 학습준비의 차이에 의해서 야기되었다. 확대가족의 부모는 핵가족의 부모에 비해서 덜 거부적인 양육태도를 보여주었으며, 확대가족의 어른들은 학습준비 (예, 숙제, 읽기, 쓰기, 예습, 복습 등)를 위해서 아동과 보내는 시간이 더 많았다. 가족구조는 아동의 문제행동에 직접적으로 영향을 미칠 뿐만 아니라, 부모의 양육태도와 가정에서의 학습준비에 영향을 주어 아동의 문제행동에 간접적으로 영향을 미치기도 한다. 한편, 확대가족에서의 조부모의 역할은 위의 결과를 뒷받침한다. 즉, 조부모는 손자녀를 돌보아주고 학습활동을 도와주며 손자녀의 정서적인 안정을 뒷받침하고 또한 부모의 스트레스를 완화시키며 가족의 화목한 분위기를 증진시키는 등의 역할을 통해서 손자녀에게 직접적, 간접적으로 영향을 미친다. 이러한 조부모의 역할은 아동의 문제행동에 근간이 되는 가족의 역동성에 영향을 미친다.

Nanoscale Resistive Switching of a Copper–Carbon-Mixed Layer for Nonvolatile Memory Applications

Hyejung Choi,Myeongbum Pyun,Tae-Wook Kim,Hasan, M.,Rui Dong,Joonmyoung Lee,Ju-Bong Park,Jaesik Yoon,Dong-jun Seong,Takhee Lee,Hyunsang Hwang IEEE 2009 IEEE electron device letters Vol.30 No.3

<P>The nanoscale resistance switching property of copper-carbon-mixed (Cu-C) layer was investigated for nonvolatile memory applications. The Cu-C layer of the cross-point cell array showed typical filament switching with two orders of on/off ratio, exhibiting stable resistance switching and a narrow distribution of set and reset voltages in the nanoscale junction. In addition, we investigated the area dependence of operation current. Based on these results and current-voltage dependence on temperature, we discussed a potential switching mechanism of Cu-C layer.</P>