• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.39-50
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• 2016

Objective: The purposes of this study were to compare the kinematics of a two-arm kettlebell swing between experts and beginners and to identify the correct postures and biomechanical key points in an attempt to prevent sports injuries induced by a kettlebell swing. Methods: Four experts (height, $169.7{\pm}1.5cm$; weight, $70.5{\pm}1.8kg$; age, $32.0{\pm}1.0years$) licensed to teach kettlebell exercises and three beginners (height, $173.7{\pm}4.1cm$; weight, $78.3{\pm}3.8kg$; age, $30.0{\pm}1.4years$) with no kettlebell exercise experience participated in this study. Each participant performed 15 repetitions of a two-arm kettlebell swing using a 16-kg weight. Joint angles, angular velocities, and peak angular velocity sequences were calculated and compared between the two groups. Results: Large ranges of motion (ROM) of the pelvic angle and hip joints were detected in the experts, while beginners showed greater ROM of the shoulder joint. Peak angular velocity magnitudes and sequences were significantly different between the two groups. Experts lifted the kettlebell upward using the hip joints, pelvis, and shoulder joints (proximal to distal order) sequentially and lowered it using the reverse order of peak angular velocities from the shoulder to hip joints. Conclusion: Mobility of the pelvic segment and hip joint are required, while stability of the other joints is needed to produce appropriate two-arm kettlebell swings. The activation and coordination of the gluteal and hamstring muscles are key points in kettlebell exercises.

• Fashion & Textile Research Journal
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• v.21 no.4
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• pp.497-508
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• 2019

Snowboarder accidents at ski resorts are increasing; therefore, it is essential to wear protective wrist, hip and knee protectors when snowboarding. However, most studies focus on the improvement of gear or expansion of safety facilities with few studies on protectors that directly safeguard the body from accidents caused by tumbling. Protectors currently on the market do not properly consider the needs of the users. Therefore, this study investigates the reality of usage and satisfaction rate of those that use snowboarding protectors along with factors deemed important upon wearing them to provide the grounds for the development of comfortable protectors. Subjects were 1,058 adults in their 20s to 40s. First, a survey was conducted regarding demographic traits as well as the wearing and purchasing of protectors. Second, 325 people that purchased and wore protectors were investigated in regards to the wearing satisfaction rate of current commercial protectors. The results showed that 86% of the 1,058 subjects wore protectors; knee protectors (72%), hip protectors (57%) and wrist protectors (38%). Important factors upon purchasing and wearing satisfaction were studied according to demographic traits, snowboarding experience, and number of snowboard rides for one season. As a result, the damage rate increased along with the number of snowboard rides for one season. Important factors considered when purchasing varied significantly according to sex, age, snowboarding experience, and favored slopes. The results of this study will help in the design of comfortable protectors for snowboarders.

• Physical Therapy Korea
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• v.28 no.2
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• pp.123-131
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• 2021

Background: Only 2% of falls in older adults result in serious injuries (i.e., hip fracture). Therefore, it is important to differentiate injurious versus non-injurious falls, which is critical to develop effective interventions for injury prevention. Objects: The purpose of this study was to a. extract the best features of surface electromyography (sEMG) for classification of injurious falls, and b. find a best model provided by data mining techniques using the extracted features. Methods: Twenty young adults self-initiated falls and landed sideways. Falling trials were consisted of three initial fall directions (forward, sideways, or backward) and three knee positions at the time of hip impact (the impacting-side knee contacted the other knee ("knee together") or the mat ("knee on mat"), or neither the other knee nor the mat was contacted by the impacting-side knee ("free knee"). Falls involved "backward initial fall direction" or "free knee" were defined as "injurious falls" as suggested from previous studies. Nine features were extracted from sEMG signals of four hip muscles during a fall, including integral of absolute value (IAV), Wilson amplitude (WAMP), zero crossing (ZC), number of turns (NT), mean of amplitude (MA), root mean square (RMS), average amplitude change (AAC), difference absolute standard deviation value (DASDV). The decision tree and support vector machine (SVM) were used to classify the injurious falls. Results: For the initial fall direction, accuracy of the best model (SVM with a DASDV) was 48%. For the knee position, accuracy of the best model (SVM with an AAC) was 49%. Furthermore, there was no model that has sensitivity and specificity of 80% or greater. Conclusion: Our results suggest that the classification model built upon the sEMG features of the four hip muscles are not effective to classify injurious falls. Future studies should consider other data mining techniques with different muscles.

• PNF and Movement
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• v.22 no.1
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• pp.71-80
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• 2024

Purpose: The purpose of this study is to compare the effects of proprioceptive neuromuscular facilitation (PNF) stretching, based on ballistic stretching and the contract-relax technique, on hip joint flexibility and muscle tone in adults with shortened rectus femoris muscles. Methods: The study involved 40 adults with shortened rectus femoris muscles, identified using the modified Thomas test. Participants were randomly divided into two groups: PNF stretching, employing the contract-relax technique, and ballistic stretching. Measurements included muscle tension, hip joint range of motion, and muscle characteristics. The rectus femoris muscle shortening effect was confirmed by the modified Thomas test, while the flexibility effect was assessed through hip joint motion range. The muscle tension effect was determined using Myoton-PRO. Results: Both stretching methods resulted in significant improvements in modified Thomas test angles and frequency, with the PNF stretching group showing notably greater changes. However, neither stretching method significantly affected decrement or stiffness measurements. These findings suggest that PNF stretching may be more effective for certain outcomes compared to ballistic stretching. Conclusion: In summary, both stretching methods positively influenced flexibility and muscle tension, with PNF stretching showing a greater impact. These findings highlight the importance of selecting the appropriate stretching technique for achieving functional improvements in muscles, which could serve as valuable indicators for preventing and treating muscle injuries in both sports and daily activities.

• Physical Therapy Korea
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• v.26 no.2
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• pp.34-48
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• 2019

Background: Fall-related injuries in older adults are a major health problem, and the risks and mechanisms of these injuries should be affected by race, culture, living environment, and/or economic status. Objects: Research articles have been systematically reviewed to understand fall-related injuries in older adults in South Korea. Methods: 128 published research papers have been found through the Korea Citation Index and the Korean Studies Information Service System, and reviewed in various perspectives, including incidents, fall death rates, medical costs, causes, injury sites and types, locations where falls occurred, prevention strategies, scholarly fields interested in fall injuries, and the role of physical therapy. Results: Fall-related injuries were found to be more common in women than in men, and the number of incidents increased with age, with the highest rate found in individuals over 85 years old. Risk of fall injury was associated with education level, comorbidities, and fear of falling. Common places where falls occurred included the bathroom, living room, stairs, and hallway. Common types of injury included bruises, fractures, and sprains in the lower extremities. Intervention strategies included exercise programs, education, and protective clothing. Scholarly fields interested in fall-related injuries in older adults included medicine, nursing, physical therapy, occupational therapy, physical education, pharmacology, oriental medicine, biomedical engineering, design, clothing, and textiles. Physical therapy intervention using proprioceptive neuromuscular facilitation has been used to improve one's balance. Conclusion: Any movement during the activities of daily living can lead to a fall. Physical therapists are highly educated to analyze human movements and should be involved in more research and practices to solve fall-related injuries in older adults.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.83-93
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• 2023

The purpose of this study is to improve pain and injury through bicycle fitting and to propose rehabilitation methods. Pain and injuries caused by bicycles can be largely divided into knee and ankle pain, wrist, shoulder, neck, and back pain, and hip pain. The cause of these pains and injuries stems from incorrect bicycle fitting and posture. In order to improve these pain and injuries and prevent recurrence, appropriate bicycle fitting and rehabilitation exercise are needed. Pain and injury are divided into kinetic pain and pain by a fixed posture. In the case of kinetic pain, rehabilitation exercise is required along with inflammatory treatment, and pain by a fixed posture should understand the exact characteristics of the body and learn and practice bicycle posture according to the body's characteristics. Through this method, it can contribute to preventing the recurrence of bicycle pain and injuries and further creating an environment where a safe bicycle culture can be established.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.3
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• pp.535-542
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• 2014

The purpose of this study was to analyze the movements of the lower extremity joints during a taekwondo kick motion called 'Juchumseogi hu Apkkoaseogi yeopchagi', which was administered to players to improve their balance, stability, and range of motion for the prevention of injuries. Eight professional players and amateur players were recruited as the subjects. Kinematic data were collected by four real-time infrared cameras. The hip joint, knee joint, and ankle joint angles were measured using instruments. During the 'Juchumseogi hu Apkkoaseogi yeopchagi' kick motion, there were small and inconsistent effects on each joint. This study processed the data using the Windows SPSS Ver. 18.0 to get an independent t-test, with the setting, p< .05. Results indicated that hip joint, knee joint, and ankle joint angles were almost significantly different between professional and amateur player during 'Juchumseogi hu apgeule Apkkoaseogi' kick motion.

• Physical Therapy Rehabilitation Science
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• v.10 no.4
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• pp.406-413
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• 2021

Objective: The purpose of this study was to investigate effects of taping technique applied to knee instability. Design: Cross sectional study. Methods: Twenty-six participants with knee instabilityparticipated in this study. They were randomly assigned to the Kinesio taping (KT) group (n=13) and the dynamic taping (DT) group (n=13). Both groups applied knee stabilization taping techniques. In order to compare the effects of each taping technique, the change in the landing error scoring system (LESS) and lower extremity joint angle wasrecorded before and after the intervention. Results: Both groups significantly decreased in the change before and after the LESS (p<0.05). At the joint angle of the lower extremities, KT group significantly reduced the valgus angle at the max knee flexion (p<0.05). In DT group knee joint flexion and hip joint flexion angles were significantly increased at foot contact (p<0.05). In max knee flexion, the knee joint flexion angle was significantly increased (p<0.05). In foot contact, max knee flexion, the knee joint valgus angle was significantly increased (p<0.05). DT group showed more significant changes in knee joint flexion angle at foot contact and hip joint flexion angle at max knee flexion. Conclusions: Dynamic taping is a clinically applicable intervention method for lowering the risk of non-contact injury in participants with knee instability and for knee stability during rehabilitation exercises.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.233-239
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• 2003

Falling related injuries are categorized as the most serious and common medical problems experienced by the elderly, hip joint fracture, one of the most serious consequences of falling in the elderly, occurs in only about 1% of falling. Nevertheless, hip fracture accounts for a considerable part of the disability, death, and medical costs associated with falling. In this study, we considered the impact angle and displacement rate in falling as another factor affecting femoral strength. Using a fresh-frozen human femur, we developed system to simulate the falling condition and then conducted the experiments changing the impact angle (0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$) of proximal femur. Also, in order to analyze the relative risk due to falling to normal situation in proximal femur, we did the static test simulating the two-legged stance condition. The results showed that the change in impact angle affected the strain distribution in proximal femur, and that a large deformation in femoral neck than in other sites. Furthermore despite low impact velocity, a large deformation in proximal femur occurred in the impact test and different strain distribution was observed compare to the static case.

• Korean Journal of Applied Biomechanics
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• v.29 no.4
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• pp.255-261
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• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.