• Journal of the Korean Society for Precision Engineering
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• 제25권9호
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• pp.126-134
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• 2008

Kendo is one of the popular sports in modem life. Head, wrist and thrust attack are the fast skill to get a score on a match. Human muscle skeletal model was developed for biomechanical study. The human model was consists with 19 bone-skeleton and 122 muscles. Muscle number of upper limb, trunk and lower limb part are 28, 60, 34 respectively. Bone was modeled with 3D beam element and muscle was modeled with spar element. For upper limb muscle modelling, rectus abdominis, trapezius, deltoideus, biceps brachii, triceps brachii muscle and other main muscles were considered. Lower limb muscle was modeled with gastrocenemius, gluteus maximus, gluteus medius and related muscles. The biomechanical stress and strain analysis of human muscle was conducted by proposed human bone-muscle finite element analysis model under head, wrist and thrust attack for kendo training.

• Journal of the Korean Society for Precision Engineering
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• 제24권11호
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• pp.116-125
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• 2007

Human muscle skeletal model was developed for biomechanical study. The human model was consists with 19 bone-skeleton and 122 muscles. Muscle number of upper limb, trunk and lower limb part are 28, 60, 34 respectively. Bone was modeled with 3D beam element and muscle was modeled with spar element. For upper limb muscle modelling, rectus abdominis, trapezius, deltoideus, biceps brachii, triceps brachii muscle and other main muscles were considered. Lower limb muscle was modeled with gastrocenemius, gluteus maximus, gluteus medius and related muscles. The biomechanical stress and strain analysis of human was conducted by proposed finite element analysis model under Kumdo head hitting motion. In this study structural analysis has been performed in order to investigate the human body impact by Kumdo head hitting motion. As the results, the analytical displacement, stress and strain of human body are presented.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.982-994
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• 2001

Commercially available software packages permit to position human models of various geometries in practical scenarios while respecting the anatomical constraints of the skeletal joints and of the bulk of the bodies. Beyond such features, the PAM-Comfort(sup)TM software has been conceived to provide direct access to the muscular forces needed by humans to perform physical actions where muscle force is required. The PAM-Comfort(sup)TM human models are made of multi-body linked anatomical skeletons, equipped with finite elements of the relevant skeletal muscles. The hyper-static problem of determination of muscle forces is solved by optimisation technique. Voluntary stiffening of muscles can be added to the basic contraction levels needed to perform a specific task. The calculated muscle forces obey Hills model. The model and software have been applied in several interesting scenarios of various fields of application, such as car industry, handling of equipment and sports activities.

• Proceedings of the KSME Conference
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.261-267
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• 2000

A mathematical model was developed to calculate the muscle force of lower extremity during the gait. We constructed a model of human locomotion, which includes a muscle-skeletal system with 7 segments and 16 lower limb muscles. Using a optimization technique, muscle forces variation of the lower extremity during the gait were generated and its result was verified by comparing a experimental results of EMG analysis. Moreover. the walking movement of the model could be compared quantitatively with those of experimental studies in human by inverse dynamics.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제35권7호
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• pp.785-790
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• 2011

The goal of this study is to estimate the force acting on the knee joint in the human body by using the Hilltype muscle model based on a musculoskeletal model of the human lower extremity in the sagittal plane. For estimating the force applied, the human leg is modeled using multi-body modeling. This leg model comprises biarticular muscles acting on two joints of the upper and lower limbs, and the muscles include some of the major muscles such as the hamstring. In order to analyze the uncertainty of the applied forces acting on the knee joint, statistical distributions of human body, leg part, parameters are required and to obtain the parameter's statistical characteristic of the part sample survey method is employed. Finally, by using the sensitivity information of the parameters, the force acting on the knee joint can be estimated.

• YAKHAK HOEJI
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• 제45권1호
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• pp.108-115
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• 2001

We have recently reported the development of a high efficiency expression vector, pCK, which can drive a high level of gene expression in mouse skeletal muscle. In this study, we tested the therapeutic potential of pCK expressing human VEGF165, pCK-VEGF in the rabbit ischemic hind limb model. To determine the optimal dose of plasmid DNA, various concentrations of pCK-CAT were injected into the muscle of a rabbit hind limb and the levels of CAT activity were determined. It was found that the expression level of the exogenously added gene became stable between 250 and 1,000 $\mu$g. Based on this result, we tested whether intramuscular transfer of 500$\mu$g of pCK-VEGF could actually modulate collateral vessel development in a rabbit ischemic hind limb model. It was found that relative to the control group injected with the pCK lacking the VEGF sequence, single intramuscular doses (500$\mu$g) of pCK-VEGF produced statistically significant augmentation of collateral vessels as determined by the angiographic vessel count, maximal blood flow by Doppler flowmeter and the number of capillaries by histology. These results suggest that a single 500$\mu$g-delivery of pCK-VEGF is potent enough to induce sufficient angiogenic activity and achieve therapeutic benefit on this rabbit model.

• The Korean Journal of Food And Nutrition
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• 제30권2호
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• pp.371-377
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• 2017

Muscle atrophy is characterized by a decrease in the mass of the muscle. With an increase in life expectancy and chronic illnesses, the incidence of muscle atrophy is increasing and the quality of life of patients is decreasing. Thus, reducing muscle atrophy is of high clinical and socio-economic importance. Mistletoe is a semi-parasitic plant that has been used as a traditional medicine in many countries to treat various human illnesses. It has been reported that Korean mistletoe extract (KME) has diverse biological functions including anti-tumor, anti-oxidant, anti-diabetic, anti-obesity properties, and extension of lifespan. Especially, we have recently reported that KME improves exercise endurance in mice, indicating its beneficial roles in enhancing the capacity of skeletal muscle. In this study, we investigated whether KME could activate the signaling pathway related to protein synthesis in a mouse model of muscle atrophy. Interestingly, KME efficiently activated the Akt/mTOR pathway, and Akt and mTOR are important signaling hub molecules for the acceleration of protein synthesis in muscle cells. In addition, KME also increased the activity of S6 kinase which is involved in the regulation of muscle cell size. Moreover, the ERK activity, required for transcription of ribosomal RNA for protein synthesis, was also enhanced in KME-treated mouse muscle. These data support the idea that KME increases muscle mass via increased protein synthesis. Our findings also suggest that Korean mistletoe might be a promising candidate for the development of functional foods that are beneficial for preventing muscle atrophy.

• Journal of the Korean Society for Nondestructive Testing
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• 제31권5호
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• pp.494-499
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• 2011

This paper presents the biomechanical analysis and evaluation technology of musculoskeletal system by multi-body human dynamic model and 3-D motion capture data. First, medical image based geometric model and material properties of tissue were used to develop the human dynamic model and 3-D motion capture data based motion analysis techniques were develop to quantify the in-vivo joint kinematics, joint moment, joint force, and muscle force. Walking and push-up motion was investigated using the developed model. The present model and technologies would be useful to apply the biomechanical analysis and evaluation of human activities.

• Korean Journal of Exercise Nutrition
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• 제16권2호
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• pp.65-71
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• 2012

Oxygen is the final acceptor of electron transport from fat and carbohydrate oxidation, which is the rate-limiting factor for cellular ATP production. Under altitude hypoxia condition, energy reliance on anaerobic glycolysis increases to compensate for the shortfall caused by reduced fatty acid oxidation [1]. Therefore, training at altitude is expected to strongly influence the human metabolic system, and has the potential to be designed as a non-pharmacological or recreational intervention regimen for correcting diabetes or related metabolic problems. However, most people cannot accommodate high altitude exposure above 4500 M due to acute mountain sickness (AMS) and insulin resistance corresponding to a increased levels of the stress hormones cortisol and catecholamine [2]. Thus, less stringent conditions were evaluated to determine whether glucose tolerance and insulin sensitivity could be improved by moderate altitude exposure (below 4000 M). In 2003, we and another group in Austria reported that short-term moderate altitude exposure plus endurance-related physical activity significantly improves glucose tolerance (not fasting glucose) in humans [3,4], which is associated with the improvement in the whole-body insulin sensitivity [5]. With daily hiking at an altitude of approximately 4000 M, glucose tolerance can still be improved but fasting glucose was slightly elevated. Individuals vary widely in their response to altitude challenge. In particular, the improvement in glucose tolerance and insulin sensitivity by prolonged altitude hiking activity is not apparent in those individuals with low baseline DHEA-S concentration [6]. In addition, hematopoietic adaptation against altitude hypoxia can also be impaired in individuals with low DHEA-S. In short-lived mammals like rodents, the DHEA-S level is barely detectable since their adrenal cortex does not appear to produce this steroid [7]. In this model, exercise training recovery under prolonged hypoxia exposure (14-15% oxygen, 8 h per day for 6 weeks) can still improve insulin sensitivity, secondary to an effective suppression of adiposity [8]. Genetically obese rats exhibit hyperinsulinemia (sign of insulin resistance) with up-regulated baseline levels of AMP-activated protein kinase and AS160 phosphorylation in skeletal muscle compared to lean rats. After prolonged hypoxia training, this abnormality can be reversed concomitant with an approximately 50% increase in GLUT4 protein expression. Additionally, prolonged moderate hypoxia training results in decreased diffusion distance of muscle fiber (reduced cross-sectional area) without affecting muscle weight. In humans, moderate hypoxia increases postprandial blood distribution towards skeletal muscle during a training recovery. This physiological response plays a role in the redistribution of fuel storage among important energy storage sites and may explain its potent effect on changing body composition. Conclusion: Prolonged moderate altitude hypoxia (rangingfrom 1700 to 2400 M), but not acute high attitude hypoxia (above 4000 M), can effectively improve insulin sensitivity and glucose tolerance for humans and antagonizes the obese phenotype in animals with a genetic defect. In humans, the magnitude of the improvementvaries widely and correlates with baseline plasma DHEA-S levels. Compared to training at sea-level, training at altitude effectively decreases fat mass in parallel with increased muscle mass. This change may be associated with increased perfusion of insulin and fuel towards skeletal muscle that favors muscle competing postprandial fuel in circulation against adipose tissues.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제41권8호
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• pp.691-701
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• 2017

The barbell squat is a fundamental physical exercise for strengthening the lower body and core muscles. It is an integral part of training and conditioning programs in sports, rehabilitation, and fitness. In this paper, we proposed a virtual test framework for squat exercises using a Smith machine to simulate joint torques and muscle forces, based on an integrated product-human model and motion synthesis algorithms. We built a muscular skeletal human model with boundary conditions modeling the interactions between the human body and a machine or the ground. To validate the model, EMG, external forces, and squat motions were captured through physical experiments by varying the foot position. A regression-based motion synthesis algorithm was developed based on the captured squat motions to generate a new motion for a given foot position. The proposed approach is expected to reduce the need for physical experiments in the development of training programs.