Background: Shoulder external rotation exercises are commonly used to improve the stabilizing ability of the infraspinatus. However, during exercise, excessive activation of the posterior deltoid compared to the infraspinatus causes the humeral head to move anteriorly in an abnormal position. Many researchers have emphasized selective activation of the infraspinatus during shoulder external rotation exercise. Objects: This study aims to delineate the optimal exercise method for selective activation of infraspinatus by investigating the muscle activities of the infraspinatus and posterior deltoid according to the four shoulder exercise methods and two forearm positions. Methods: Thirty healthy individuals participated in this study. The participants were instructed to perform shoulder external rotation exercises following four exercise methods: sitting external rotation (SIER); standing external rotation at 90° abduction (STER); prone external rotation at 90° abduction (PRER); side-lying external rotation (SLER), and two forearm positions (neutral, supinated). The electromyography (EMG) signal amplitude was measured during each exercise. Surface EMG signals were recorded from the posterior deltoid, infraspinatus, and biceps brachii. Results: EMG results of the infraspinatus and posterior deltoid in PRER, were significantly higher than that of the other exercises (p < 0.01). The EMG ratio (infraspinatus/posterior deltoid) in SIER was significantly higher than that of the other exercises. EMG activation of the posterior deltoid in SIER, PRER, and SLER was significantly higher in neutral than in supinated (p < 0.01). Furthermore, the EMG of the infraspinatus in SIER was significantly higher in neutral than in supinated (p < 0.01). The EMG ratio (infraspinatus/ posterior deltoid) in SIER was significantly higher in neutral than in supinated (p < 0.05.) Contrarily EMG ratios in PRER and SLER were significantly higher in supinated than in neutral (p < 0.05). Conclusion: The results show that clinicians should consider these exercise methods and forearm positions when planning shoulder external rotation exercises for optimal shoulder rehabilitation.

본 연구는 3차원 영상분석을 이용하여 백핸드 백월 보스트 동작의 운동학적 변인에 대하여 라켓과 하박의 숙련도간 기술적인 차이를 분석한 결과는 다음과 같다. 첫째, 소요시간에서 숙련자가 비숙련자보다 빠르게 나타났다. 둘째, 라켓의 변위는 다운스윙 구간에서 숙련자가 좌우와 전후는 길게, 상하는 낮게 나타났다. 셋째, 팔로스루 구간에서 라켓의 변위는 숙련자가 비숙련자보다 짧게 나타났다. 넷째, 라켓의 합성속도는 비숙련자가 높게 나타났다.

Background: Lateral epicondylitis (LE) is the most common chronic musculoskeletal conditions of the upper extremity with pain and wrist extension disability. The tendon which is most affected is the extensor carpi radialis brevis (ECRB). Previous study evaluated the effect of taping technique on patient with LE, but no study investigated the changes of electromyography (EMG) on ECRB when using dynamic taping (DT) technique. Objects: The aim of this study was to investigate the effect of DT technique using dynamic tape on muscle activity of ECRB during wrist isometric extension, isotonic extension and flexion. Methods: Twenty-one healthy subjects volunteered to participate in this study. Subjects were instructed to perform wrist isometric extension, isotonic extension and flexion without and with DT on origin area of ECRB. Wrist isometric extension was performed at 75%, 50% and 25% (%maximal voluntary contraction force), respectively, based on maximum contraction force. Isotonic extension and flexion test used dumbbell. EMG data was collected from ECRB. Results: EMG of ECRB were statistically significant decrease in wrist isotonic extension after DT (p < 0.05). Significant increase in wrist isometric extension during 25% and 50% force task (p < 0.05). Conclusion: This study applied DT technique to suppress the wrist extensor muscles in 21 healthy adults in their twenties. Change in muscle activity was compared in the ECRB muscle during wrist isometric extension, isotonic extension and flexion task. Based on the results of this study, the DT technique applied to the wrist and forearm area can reduce the load on the wrist extensors when the wrist performs various movements during daily life movements or repetitive tasks, and by using these effects, excessive stress is applied to tennis elbow patients.

Background : Although plank exercises is reported to the changes in muscle activity of the deep muscles and superficial muscles among the core muscles. However, no study has examined the effects of forearm plank exercise on tone and stiffness in the superficial back line muscle. Objective: To compare the effects of sling forearm plank exercises and mat forearm plank exercises on the superficial back line muscle tone and stiffness. Design: Randomized controlled clinical trial (single blind) Methods: The subjects were randomized to sling forearm plank exercise group (N = 8) or mat forearm plank exercise group (N = 8). The measurements were taken for each research group following exercises: the muscle tone and stiffness of upper lumbar muscles, lower lumbar muscles, long head of biceps femoris, and medial part of gastrocnemius among the superficial back line muscles. Results: Sling forearm plank exercise group Indicated statistically significant increases in stiffness of medial part of gastrocnemius (p<.05). However, mat forearm plank exercise group reported no statistically significant in muscle tone and stiffness of all measured muscles. No significant differences in measured variables were found between the groups. Conclusions: These results suggest that the forearm plank exercise performed with an unstable surface in the defined sling can increase the stiffness of calf muscle, but it is unlikely to achieve increases in muscle tone and stiffness of the overall superficial back line muscles.

This study aimed to measure the grip strength of the dominant and non dominant hands of right-handed normal adults in the supination, pronation, and neutral positions of the forearms. The subjects of this study were instructed to make the standard posture suggested by the American Society of Hand Therapists (ASHT) in order to minimize the impact of changes in the posture of the body as follows. The grips strength was statistically different between groups (p<.05). In the follow up test using Scheffe test, the grips in the neutral position and supinator position did not show any difference, while the grip in the pronation was smaller than those of the above two other positions. The grips of the mainly used forearm and non-mainly used forearm of the study target did not show any statistically significant difference in the neutral, supinator and pronation positions of the forearm. This study is expected to provide basic information for studying the impact of the positions of the forearms on grip strength, assessing the prehensility of patients in clinical settings, and setting therapeutic goals.ㅍ

The purpose of this study is to analyze the grip strength by the girth of upper arm and forearm and their muscle activities by duration of grip strength. The subjects were consisted of 20 healthy adults(10 males & 10 females) who had no medical history of neurological and surgical problems with their arms. Girth of upper arm/ forearm and maximum grip strength for 4sec and 30sec were measured. Muscle activity was by wireless electrode EMG system. Co-relation of girth of upper arm/ forearm was significantly high. Upper arm's muscle activity performed for 4sec and 30sec was significantly high. In this study. It suggests that training of upper arm should be performed with the training of grip strength because both of upper arm and forearm affected grip strength.

수공구 사용시 과도한 힘은 작업성 근골격계 질환을 일으킬 수 있는 주요 원인중 하나이다. 이와 관련하여, 수공구 파지시 인체 내부에 부과되는 근력과 외적으로 작용된 힘 간의 비율을 이해하는 것이 중요하며, 이는 근육에 부과되는 과도한 힘을 최소화 시키고, 작업에 필요한 힘의 효율성을 극대화 시키는데 필수적이라 할 수 있다. 이러한 비율과 관련하여 많은 연구가 되어 왔으나, 대부분 수리적 인체역학적 모델과 같은 간접적 추정 방법에 의거하고 있는 실정이다.

The aim of this study was to compare electromyography activity for long and lateral heads of triceps brachii muscle according to forearm positions during different triceps strengthening exercises. The muscle activities for long and lateral head of triceps brachii were measured by surface electromyography. Fifteen healthy volunteers participated for this study and performed elbow extension in three different elbow extension exercises (elbow extension in a supine position; EES, elbow extension with shoulder abduction at 90 degrees in a prone position; EESA, and elbow extension with one arm at the side of the trunk in a prone position; EESP) and forearm positions (supination, neutral, and pronation). A two-way repeated measures ANOVA was used to compare the effects of the exercise positions and forearm positions. The EMG activities of the long head of the triceps brachii increased significantly during EESP with forearm supination, whereas the activity of the lateral head of the triceps brachii increased significantly during EESA with the forearm in a neutral position (p<.05). The results of this study suggest that exercise positions and forearm positions should be considered for selectively strengthening the long and lateral heads of triceps brachii muscles.

목적 : 본 연구의 목적은 손잡이 굵기 변화에 따라 전완의 회전근력의 최대 힘 효율(peak torque), 총일량(total work), 평균파워(average power)가 각각의 굵기에서 차이가 있는지 알아보기 위함이다. 연구 방법 : 성인 남성 21명 대상으로 손잡이 굵기는 세 개(13, 16, 19cm)로 나뉘어 Biodex System 3 Pro dynamometer 등속성 근력 검사(isokinetic test)를 통해 각각의 손잡이 굵기에 대하여 2회씩 반복 측정된 측정값의 평균값을 분석에 사용하였다. 손잡이 굵기에 대하여 전완의 회내력과 회외력 값들 중에서 최대 힘 효율(peak torque), 총일량(total work), 평균파워(average power)들의 차이를 알아보았다. 결과 : 최소, 중간 그리고 최대 크기의 손잡이 굵기에 따른 최대 힘 효율, 총일량 그리고 평균파워가 유의한 차이가 있었다(p<.01). 최소, 최대 크기의 손잡이 굵기에 비해 중간 크기의 손잡이 굵기에서 최대 힘 효율, 총일량 그리고 평균파워가 상대적으로 높은 수치를 나타내었다. 최대 힘 효율, 총일량 그리고 평균파워를 비교 분석해 보았을 때 회외 동작 시 중간과 최대, 최소와 중간 간에는 유의한 차이가 있었으나(p<.05), 최소와 최대 간에는 유의한 차이가 없었다. 최대 힘 효율, 총일량 그리고 평균파워를 비교 분석해 보았을 때 회내 동작 시 중간과 최대, 최소와 중간, 최소와 최대 간에는 유의한 차이가 있었다(p<.05). 결론 : 연구 결과 손잡이를 쥐고 있는 상태에서 전완의 회전근력 변화가 손잡이 굵기 변화에 따라 회내력과 회외력이 최소, 중간 그리고 최대 크기의 손잡이 굵기에서 최대 힘 효율, 총일량 그리고 평균파워가 유의한 차이가 나타난다는 것을 알게 되었다. 향후 성별에 따른 손잡이 굵기가 전완의 회전력에 미치는 영향과 양손을 따른 비교 연구하여 적절한 손잡이 굵기를 알아보는 연구가 필요할 것이다.

The objective of this study was to compare the differences on the activity and power of the wrist flexors and extensors in subjects before the use of a wrist extension splint, after nighttime wearing of the splint, and after daytime wearing of the splint. Ten healthy male and ten healthy female students (mean: 22.4±1.2 years old) volunteered to wear custom-made wrist splints either during the night or during the day, The hand force of the wrist flexor and extensor, and grip force were measured by PowerTrack II and Dynatron, respectively. At the same time, the activities of the wrist flexor and extensor were recorded by' surface electromyography. The maximal hand force and motor unit recruitment of the flexor carpi ulnatis (FCU) increased significantly (p<.05) when tile subjects wore the wrist splints during the daytime, but the maximal hand power of the FCU decreased with nighttime use of the splints. The maximal hand power and motor unit recruitment of the extensor carpi radialis (ECR) and the ECR/FCU ratio decreased both during nighttime and daytime use. The decrement of the ECR/FCU ratio was significant (p<.05). Wearing a wrist extension splint during nighttime led to the maintenance of a lengthened position of the wrist flexor, resulting in the wrist flexor becoming weak. Wearing a wrist extension splint during the day induced the wrist flexors to be greater. In healthy people, the imbalance between the wrist flexors and extensors may be caused by the use of a wrist extension splint. This study indicates that therapists have to consider whether a splint will be effective, as well as the wearing time, when prescribing splints to people with problems of the musculoskeletal system.

This study was designed to develop an objective method of strength measurement of muscles controlling the wrist joint in normal subjects. Forty subjects (20 male, 20 female) with a mean age of 22 years, were tested isokinetically at and . Results were as follows, 1) Peak torque for wrist flexors, extensors were significantly different for both speeds, but wrist ulnar deviator, radial deviator peak torques were not, 2) Mean values for all muscle groups controlling the wrist were not significantly different for both speeds in the female group, 3) All mean values at both and were significantly different between males and females, 4) Means and standard deviations of wrist joint angle of movement at peak torque were determined.

This paper presents the kinematic modeling of the human forearm rotation constructed with a spatial four-bar linkage. Especially, a circumduction of the distal ulna is modeled for a minimal displacement of the position of the hand during the forearm rotation from the supination to the pronation. To establish its model, four joint types of the four-bar linkage are, firstly, assigned with the reasonable grounds, and then the spatial linkage having the URUU (Universal-Revolute-Universal-Universal) joint type is proposed. Kinematic analysis is conducted to show the behavior of the distal radio-ulna as well as to evaluate the angular displacements of all the joints. From the simulation result, it is, finally, revealed that the URUU spatial linkage can be substituted for the URUR (Universal-Revolute-Universal-Revolute) spatial linkage by a kinematic constraint.

This paper presents a multiple DoFs (degrees-of-freedom) prosthetic forearm and sEMG (surface electromyogram) pattern recognition and motion intent classification of forearm amputee. The developed prosthetic forearm has 9 DoFs hand and single-DoF wrist, and the socket is designed considering wearability. In addition, the pattern recognition based on sEMG is proposed for prosthetic control. Several experiments were conducted to substantiate the performance of the prosthetic forearm. First, the developed prosthetic forearm could perform various motions required for activity of daily living of forearm amputee. It was able to control according to shape and size of the object. Additionally, the amputee was able to perform ‘tying up shoe’ using the prosthetic forearm. Secondly, pattern recognition and classification experiments using the sEMG signals were performed to find out whether it could classify the motions according to the user’s intents. For this purpose, sEMG signals were applied to the multilayer perceptron (MLP) for training and testing. As a result, overall classification accuracy arrived at 99.6% for all participants, and all the postures showed more than 97% accuracy.

피부의 탄성은 주로 콜라겐, 탄력섬유 등이 풍부한 진피의 영향을 받는다. 하지만, 피부의 가장 바깥층인 각질층의 변화가 피부의 기계적인 특성에 어떠한 영향을 미치는지에 대해선 아직 명확하게 밝혀지지 않고 있다. 이에 본 연구에서는 새롭게 디자인한 시험방법을 통해 피부 깊이별 탄성 특성과 수화과정을 통한 각질층 변화가 피부 탄성 특성에 어떻게 영향을 주는지를 알아보았다. 또한 이 방법을 이용해 얼굴피부와 하박내측 피부의 특성을 비교 평가하였다. 25-40세 연령의 건강한 성인 10명을 대상으로, 피부 깊이별 탄성 특성을 연구하기 위해 CutometerⓇ의 음압을 다양하게 설정하여 얼굴피부와 하박내측 피부의 탄성 특성을 측정하여 비교 평가하였다. 음압은 100, 200, 300, 450 mbar로 구분하여 측정하였다. 또한 충분한 수화과정을 통해 각질층의 변화를 유도하고, 다양한 음압 조건에서 피부 탄성 특성을 측정하였다. 그 결과, 음압 조건을 달리함에 따라 피부 깊이에 따른 탄성 특성 측정이 가능함을 확인하였다. 그리고 하박내측 피부의 R7 값은 모든 음압조건에서 얼굴피부보다 통계적으로 유의하게 높았다(p < 0.05). 또한 수화과정에 의한 각질층의 변화는 피부탄성 특성에 영향을 줄 수 있음을 확인하였다. 특히 얼굴피부의 R7 값은 300 mbar 음압조건에서 수화전 상태의 피부에 비해 통계적으로 유의하게 변화하였다(p < 0.05). 그리고 전체적으로 얼굴피부가 하박내측 피부보다 수화과정에 더 크게 영향을 받고 있음을 알 수 있었다. 이러한 결과는 다양한 음압조건과 피부 수화 과정을 활용한다면, 각질층 및 표피층의 변화를 고려한 피부탄력특성을 평가할 수 있는 유용한 시험법이 될 것으로 사료된다.

Robot arms are being increasingly used in various fields with special attention given to unmanned systems. In this research, we developed a high payload dual-arm robot, in which the forearm module is replaceable to meet the assigned task, such as object handling or lifting humans in a rescue operation. With each forearm module specialized for an assigned task (e.g. safety for rescue and redundant joints for object handling task), the robot can conduct various tasks more effectively than could be done previously. In this paper, the design of the high payload dual-arm robot with replaceable forearm function is described in detail. Two forearms are developed here. Each of forearm has quite a different goal. One of the forearms is specialized for human rescue in human familiar flat aspect and compliance parts. Other is for general heavy objects, more than 30 kg, handling with high degree of freedom more than 7.