Group Ⅲ Mechanoreceptors Increase the Discharge of Single Renal Sympathetic Efferents in Decerebrate Cats During Tendon Stretch

Hyun-Min Choi,Hosung Nho,In-Tae Ko,Chan-Ho Park,Jong-Kyung Kim 한국생활환경학회 2008 한국생활환경학회지 Vol.15 No.4-2

The renal vasoconstriction serves to shunt blood flow from the kidney toward active skeletal muscles during exercise. However, it is not well known that the stimulation of group Ⅲ muscle afferents reflexly increases sympathoexci-tation in the renal arteries. Therefore, we recorded single renal nerve filament response to tendon stretch before and after injection of gadolinium into the popliteal artery in decerebrate cats. In control experiment, the impulse activity of single renal nerve efferent was significantly increased during tendon stretch, while gadolinium significantly reduced the renal sympathetic impulse activity. The blood pressure responses induced by the mechanoreflex activation were significantly increased in both conditions, but the pressor response was substantially attenuated after injection of gadolinium. We conclude that the mechanical component of the exercise pressor reflex may contribute to evoke the renal vasoconstriction during exercise.

Effects of Ovarian Cycle on Hemodynamic Responses during Dynamic Exercise in Sedentary Women

Choi, Hyun-Min,Stebbins, Charles L.,Nho, Hosung,Kim, Mi-Song,Chang, Myoung-Jei,Kim, Jong-Kyung The Korean Society of Pharmacology 2013 The Korean Journal of Physiology & Pharmacology Vol.17 No.6

This study tested the hypothesis that effects of the menstrual cycle on resting blood pressure carry over to dynamic exercise. Eleven healthy females were studied during the early (EP; low estrogen, low progesterone) and late follicular (LP; high estrogen, low progesterone) menstrual phases. Stroke volume (SV), heart rate (HR), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), and total vascular conductance (TVC) were assessed at rest and in response to mild and moderate cycling exercise during EP and LP. During EP, compared to LP, baseline SBP ($111{\pm}1$ vs. $103{\pm}2$ mmHg), DBP ($71{\pm}2$ vs. $65{\pm}2$ mmHg) and mean arterial pressure (MAP) ($84{\pm}2$ vs. $78{\pm}1$ mmHg) were higher and TVC ($47.0{\pm}1.5$ vs. $54.9{\pm}4.2$ ml/min/mmHg) was lower (p<0.05). During exercise, absolute values of SBP (Mild: $142{\pm}4$ vs. $127{\pm}5$ mmHg; Moderate: $157{\pm}4$ vs. $144{\pm}5$ mmHg) and MAP (Mild: $100{\pm}3$ vs. $91{\pm}3$ mmHg; Moderate: $110{\pm}3$ vs. $101{\pm}3$ mmHg) were also higher, while TVC was lower (Mild: $90.9{\pm}5.1$ vs. $105.4{\pm}5.2$ ml/min/mmHg; Moderate: $105.4{\pm}5.3$ vs. $123.9{\pm}8.1$ ml/min/mmHg) during EP (p<0.05). However, exercise-induced increases in SBP, MAP and TVC at both work intensities were similar between the two menstrual phases, even though norepinephrine concentrations were higher during LP. Results indicate that blood pressure during dynamic exercise fluctuates during the menstrual cycle. It is higher during EP than LP and appears to be due to additive effects of simultaneous increases in baseline blood pressure and reductions in baseline TVC.

Confirmation of Physical Fitness Based on Polynomial Regression Evaluation of Muscle Mass Percentage against BMI in Korean Male Junior High School Students

Nozomi Tanaka,Katsunori Fujii,Jun-Dong Kim,Hosung Nho(노호성) 한국생활환경학회 2010 한국생활환경학회지 Vol.17 No.6

This study examined physical strength and motor ability based on a polynomial regression analysis of muscle mass percentage against BMI in South Korean junior high school students. The subjects were 201 students in the first year of junior high school. Measurements of physique (body height and weight) and body composition (BMI, fat mass, body fat percentage, muscle mass, and muscle mass percentage) were carried out. In tests of physical strength, items from the physical fitness test were adopted for the Korean students, and sit-ups, sit-and-reach, push-ups, and 20-meter shuttle run were measured. In the polynomial regression analysis of muscle mass percentage against BMI, a high reverse correlation (r = 0.76) was shown. In normal body type classified by standard polynomial regression evaluation chart, the group with excessive development of muscle mass was superior to other groups in sit-ups, push-ups, and 20-meter shuttle run. No significant differences were shown in any items of physical strength in slim body type students, and the group with excessive development of muscle mass in the fat body type was superior to other groups in the 20-meter shuttle run. In other words, the level of qualitative accumulation of muscle did not influence physical strength in specific physiques like slim and fat body types. In the present study, BMI was newly placed as an index of a muscle mass percentage, and it was shown that physical strength could be readily understood by body fatness judgment based on BMI.

Effects of Ovarian Cycle on Hemodynamic Responses during Dynamic Exercise in Sedentary Women

Hyun-Min Choi,Charles L. Stebbins,Hosung Nho,Mi-Song Kim,Myoung-Jei Chang,Jong-Kyung Kim 대한생리학회-대한약리학회 2013 The Korean Journal of Physiology & Pharmacology Vol.17 No.6

This study tested the hypothesis that effects of the menstrual cycle on resting blood pressure carry over to dynamic exercise. Eleven healthy females were studied during the early (EP; low estrogen, low progesterone) and late follicular (LP; high estrogen, low progesterone) menstrual phases. Stroke volume (SV), heart rate (HR), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), and total vascular conductance (TVC) were assessed at rest and in response to mild and moderate cycling exercise during EP and LP. During EP, compared to LP, baseline SBP (111±1 vs. 103±2 mmHg), DBP (71±2 vs. 65±2 mmHg) and mean arterial pressure (MAP) (84±2 vs. 78±1 mmHg) were higher and TVC (47.0±1.5 vs. 54.9±4.2 ml/min/mmHg) was lower (p<0.05). During exercise, absolute values of SBP (Mild: 142±4 vs. 127±5 mmHg; Moderate: 157±4 vs. 144±5 mmHg) and MAP (Mild: 100±3 vs. 91±3 mmHg; Moderate: 110±3 vs. 101±3 mmHg) were also higher, while TVC was lower (Mild: 90.9±5.1 vs. 105.4±5.2 ml/min/mmHg; Moderate: 105.4±5.3 vs. 123.9±8.1 ml/ min/mmHg) during EP (p<0.05). However, exercise-induced increases in SBP, MAP and TVC at both work intensities were similar between the two menstrual phases, even though norepinephrine concentrations were higher during LP. Results indicate that blood pressure during dynamic exercise fluctuates during the menstrual cycle. It is higher during EP than LP and appears to be due to additive effects of simultaneous increases in baseline blood pressure and reductions in baseline TVC.

중년 여성의 체력과 동맥경직도의 관련성

정은지(Eunji Jung),박세정(Saejong Park),노호성(Hosung Nho) 한국생활환경학회 2013 한국생활환경학회지 Vol.20 No.2

The purpose of this study was to examine the relationship between arterial stiffness and physical fitness in middle-aged women and the independent influence of cardiorespiratory fitness (CRF) or muscle fitness (MF) on arterial stiffness. The participants performed a physical fitness test including grip strength, sit-ups, 20 m shuttle run, sit and reach, 10 m × 4 rep shuttle run and long jump. The indexes of MF (sum of the z scores for relative grip strength and sit ups) and TF (sum of the z-scores for all fitness factors) was calculated. Brachial-ankle pulse wave velocity (ba PWV) was measured to assess the arterial stiffness. The results were following: significant differences were found in total cholesterol (P < 0.05), HDLC (P < 0.05), LDLC (P < 0.01), triglyceride (P < 0.05), Framingham Risk Score (P < 0.001) and coronary heart disease risk (P < 0.001) among the levels of arterial stiffness but not in body mass index or percent body fat. There were significant negative correlations between health-related or skill-related physical fitness and CHD risk, and there were significant differences in CRF (P < 0.001), MF (P < 0.001) or TF (P < 0.001) among the levels of the CHD risk. The arterial stiffness has significant negative correlations with muscular strength (P < 0.05), muscular endurance (P < 0.001), cardiorespiratory (P < 0.001), agility (P < 0.05), or power (P < 0.05), and also with MF(P < 0.001) or TF(P < 0.001). The lowest levels of arterial stiffness presented higher CRF(P < 0.001), MF(P < 0.001) or TF(P < 0.001) and both CRF and MF were all independent factors for the arterial stiffness. These findings suggest that a comprehensive exercise program including not only cardiorespiratory endurance but also muscular strength, muscular endurance, agility and power may be needed for improving the arterial stiffness.

노인 남녀의 일상생활체력 측정을 이용한 VO<SUB>2max</SUB> 추정식 제안

김경애(Kyung-Ae Kim),노호성(Hosung Nho) 한국발육발달학회 2020 한국발육발달학회지 Vol.28 No.2

This study proposed a multiple regression equation for predicting VO2max of elderly men and women using activity of daily living variables required to conduct daily activities. The subjects of this study were 58 elderly men (72.4±5.9 yrs) and 117 elderly women (73.4±4.5 yrs) aged 65-90 who belong to the senior welfare center. The maximal graded exercise test using a cycle ergometer and activity of daily living representing muscle strength, endurance, static and dynamic flexibility, mobility, and agility were measured. For statistical processing, multiple regression analysis was performed, and the statistical significance level was α = .05. As a result, the VO_2max estimation formula for the elderly was 0.419 (standing up and sitting down a chair) + 0.199 (leg endurance against wall) + 5.383, and R²=0.406. In addition, the VO2max estimation formula for elderly women is - 0.737 (standing up from a supine position) - 0.144 (waking around two cones in a figure 8) - 0.135 (%body fat) + 0.042 (one leg balance with eyes open) + 29.395, R²=0.367 was calculated. The conclusion is that if the maximal graded exercise test is not available, it is considered that VO2max of the elderly can be predicted properly by using the estimation formula calculated based on the activity of daily living variable.

비만을 동반한 폐경이 Group 구심성 신경의 대사적 수용기에 미치는 영향

김지연(Ji-Yeun, Kim),김종경(Hosung Nho),노호성(Jong-Kyung Kim),장명재(Myoung Jei Chang) 한국생활환경학회 2012 한국생활환경학회지 Vol.19 No.6

Both obesity and menopause cause the dysfunction of autonomic nervous system. Recent human studies have reported that exercise pressor reflex (EPR)-mediated increases in blood pressure are exaggerated in obese or postmenopausal women. Whether these findings can be extended to both obese and postmenopausal women remains unclear. Mean arterial pressure (MAP), cardiac output (CO), and total vascular conductances (TVC) were measured in normal premenopausal women (NPW; n = 11; 36 ± 2 yr), normal postmenopausal women (NPOW; n = 14; 57 ± 1 yr), and overweight postmenopausal women (OPOW; n = 14; 56 ± 1 yr) at baseline, and during static handgrip at 50% maximal voluntary contraction (MVC) followed by a period of postexercise muscular ischemia (PEMI) to isolate the metabolic component of the EPR. Changes in MAP from baseline were augmented in OPOW subjects during both 50% MVC handgrip (P < 0.05), and these group differences were maintained during PEI (P < 0.05). There were no differences in heart rate (HR), stroke volume (SV), and CO during hand grip exercise and PEMI among groups. Even though there was no group difference in TVC during exercise and PEMI, the TVC tended to be abolished in OPOW group. In summary, compared with NPW subjects, OPOW group exhibit exaggerated pressor responses to handgrip exercise that are maintained during PEMI, indicating that activation of the metabolic component of the EPR is augmented in OPOW group. The exaggerated pressor response mediated by the muscle metaboreflex activation in OPOW group mainly occurs via preperial vasoconstriction with little change in CO.

유산소운동이 중년 비만여성의 대사적 수용기 자극에 따른 심혈관 반응에 미치는 영향

한우람(Woo-Ram Han),최현민(Hyun-Min Choi),노호성(Hosung Nho),김종경(Jong-Kyung Kim) 한국생활환경학회 2011 한국생활환경학회지 Vol.18 No.4

The purpose of this study was to investigate whether aerobic exercise training improves the muscle metaboreflex in obese women. Eight obese women were recruited in this study. Subjects performed 3 min static handgrip exercise and 2 min of post exercise muscular ischemia (PEMI) while heart rate (HR), stroke volume (SV), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured followed by the calculation of cardiac output, mean arterial pressure (MAP), and total vascular conductance (TVC). All subjects completed 12 wk aerobic exercise training consisting of 3 times/wk and 40 min per session. Subjects walked/ran at the exercise intensity of 50% maximum heart rate on the treadmill. In order to maintain the target heart rate, the speed and grade were manipulated every two weeks. With aerobic exercise training, SBP, DBP and MAP were significantly decreased during static exercise, while TVC was significantly increased. Both SBP and MAP responses mediated by the muscle metaboreflex were significantly decreased. These results indicate that aerobic exercise training altered the strength of the muscle metaboreflex. Thus, regular aerobic exercise training may improve impaired peripheral vasoconstriction and exaggerated blood pressure response induced by the muscle metaboreflex in obese women.

여자스포츠선수의 신체적 스트레스성 초경지연에 대한 검증

藤井勝紀(Katsunori Fujii),김준동(Jun Dong Kim),노호성(Hosung Nho) 한국발육발달학회 2011 한국발육발달학회지 Vol.19 No.1

In this study, to determine delayed menarche in individual female athletes, the age at maximum peak velocity of height and the age at menarche of female athletes were applied to the delayed menarche evaluation system developed by Fujii. The age at maximum peak velocity of BMI and the interval with age at menarche were then analyzed for girls judged to have had delayed menarche. An attempt was made to verify the frequency with which physical stress gives rise to delayed menarche. The subjects were 144 female athletes in their final year of high school who had participated in national sports tournaments during their high school years. A control group was made up of 78 girls who did not regularly participate in sports. Information including age, age at menarche, and athletic practice was obtained from a questionnaire given to the athletes and control group. Data were also obtained on the girls longitudinal growth in height and weight from the first year of elementary school (6 years old) to the final year of high school. BMI was calculated from this data, and the wavelet interpolation method was applied for changes in height and BMI with age from 6 to 17 years old. It was found that among female athletes judged to have had delayed menarche the physical stress type of delayed menarche was much more common than fat-related delayed menarche. Therefore, it is speculated that physical stress acts a large role in delayed menarche in athletes.

Beetroot 섭취가 경계성 고혈압자의 GroupIV 대사적 수용기에 미치는 영향

김보희(Bo Hee Kim),최현민(Hyun Min Choi),노호성(Hosung Nho),김경애(Kyung Ae Kim),정은지(Eun Ji Jung),김종경(Jong Kyung Kim) 한국발육발달학회 2014 한국발육발달학회지 Vol.22 No.3

It is reported that beetroot juice supplementation reduces blood pressure in healthy subjects at rest. However, It is not known that beetroot juice supplementation alters the pressor response mediated during exercise and by the muscle metaboreflex activation in prehypertension. Thus, the purpose of this study was to investigate the effects of dietary nitrate derived from beetroot (BR) on muscle metaboreflex and endothelial function in prehypertension compared with placebo (PR). Eleven prehypertensives (24±2 yrs) were recruited in this study. All subjects were assigned in a randomized, double-blind, crossover design to receive BR (70 mL/ day, ~5.6 mmol of NO3 -and PL (70 mL/day, no NO3 -) for 15 days. The subjects completed 2 min static handgrip exercise at 50% maximal voluntary contraction followed immediately by post exercise muscle ischemia(PEMI). On day 15, the same protocol was repeated after BR or PL supplementation. All subjects were continuously instrumented to measure heart rate, stroke volume, systolic blood pressure (SBP), diastolic blood pressure (DBP), and obtain cardiac output(CO), mean arterial pressure(MAP), total peripheral resistance (TPR) at rest and during static exercise and PEMI. Compared with PL, BR significantly increased resting plasma nitrate/nitrite (NOx) concentration (PL: 147.8±10.3 vs. BR: 193.7±19.2, p <.05) and decreased SBP (133±1 vs 128±2 mmHg, p <.05). Normalized flow mediated dilation (FMD) was significantly increased (BR: 2.24±0.3 vs PL: 1.86±0.2, p <.05). There were no differences in CO, MAP, and TPR between BR and PL at rest and during static exercise and muscle metaboreflex activation. Thus, this study indicates that beetroot juice supplementation improves the endothelium function and reduce blood pressure at rest, while no effects on muscle metaboreflex. Therefore, this study suggests that BR diet are regarded as healthy and associated with low incidence of cardiovascular disease in prehypertention.