• Korean Journal of Applied Biomechanics
• /
• v.31 no.4
• /
• pp.234-240
• /
• 2021

Objective: The purpose of this study is to analyze the distance, number, duration, velocity of sprints generated during women's hockey competition by position to identify sprint patterns. Method: The data was collected in 17 matches between 2016 and 2018, 49 elite women's hockey players were tested using SPI-HPU to identify differences by position using SPSS 25.0. A total of 376 Sprint information was utilized. Results: First, women's hockey players all showed significant differences in the number of sprints, duration, distance, and max velocity depending on their positions. Second, there was a significant difference in the number of sprints in the difference between quarters. And the factors of duration, distance, and max velocity showed differences between positions. Third, according to the results, there were differences in the number of times, duration, distance, and max velocity in the difference between positions. Conclusion: These results can be confirmed the sprint patterns of depends on position during the women's hockey game and can be used as information for the development of physical and tactical training programs.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.2
• /
• pp.119-127
• /
• 2005

The purpose of this research helps to make full use for perfect performance by grasping the defects of Ropez motion performed by athlete CSM who was under the training for the 28th 2004 Athene Olympic Garnes, and by presenting complementary methods. For the better Ropez motion which had been performed by CSM for the 1st dispatch selection test and the final for the 28th Athene Olympic Game was analyzed with 3-dimensional cinematographic method. Here are the conclusions: 1. During the board contact phase, powerful kicking and rapid forward flexion motion of upper body make increasing vertical velocity of C. O. G and enlarging body angle. 2. It was indicated that rapid forward flexion motion of upper body during the board contact phase get a large body angle in horse take-off. 3. rapid forward flexion motion of upper body during the board contact phase makes a longer time at horse contacting phase. It showed that this result increased velocity of horse take-off causing by powerful blocking motion. 4. Increasing of air-borne height during pre- flight phase, makes a higher C. O. G; and larger angle of hip, angle of knee and body angle in the landing phase. And it revealed that these results have a stable landing.

• Korean Journal of Applied Biomechanics
• /
• v.29 no.2
• /
• pp.61-70
• /
• 2019

Objective: This study aimed to investigate the characteristics of the declination of the subtalar joint rotation axis and the structural features of the ankle joint complex such as rear-foot angle alignment and ligament laxity test between chronic ankle instability (CAI) patients and healthy control. Method: A total of 76 subjects and CAI group (N=38, age: $23.11{\pm}7.63yrs$, height: $165.67{\pm}9.54cm$, weight: $60.13{\pm}11.71kg$) and healthy control (N=38, age: $23.55{\pm}7.03yrs$, height: $167.92{\pm}9.22cm$, weight: $64.58{\pm}13.40kg$) participated in this study. Results: The declination of the subtalar joint rotation axis of the CAI group was statistically different from healthy control in both sagittal slope and transverse slope. The rear-foot angle of CAI group was different from a healthy control. Compared to healthy control, they had the structure of rear-foot varus that could have a high occurrence rate of ankle varus sprain. CAI group had loose ATFL and CFL compared to the healthy control. Conclusion: The results of this study showed that the deviation of the subtalar joint rotation axis and the structural features of the ankle joint complex were different between the CAI group and the healthy control and this difference is a meaningful factor in the occurrence of lateral ankle sprains.

• Korean Journal of Applied Biomechanics
• /
• v.32 no.1
• /
• pp.1-8
• /
• 2022

Objective: This study proposes a methodology to analyze important variables that have a significant impact on the putting direction prediction using a machine learning-based putting direction prediction model trained with IMU sensor data. Method: Putting data were collected using an IMU sensor measuring 12 variables from 6 adult males in their 20s at K University who had no golf experience. The data was preprocessed so that it could be applied to machine learning, and a model was built using five machine learning algorithms. Finally, by comparing the performance of the built models, the model with the highest performance was selected as the proposed model, and then 12 variables of the IMU sensor were applied one by one to analyze important variables affecting the learning performance. Results: As a result of comparing the performance of five machine learning algorithms (K-NN, Naive Bayes, Decision Tree, Random Forest, and Light GBM), the prediction accuracy of the Light GBM-based prediction model was higher than that of other algorithms. Using the Light GBM algorithm, which had excellent performance, an experiment was performed to rank the importance of variables that affect the direction prediction of the model. Conclusion: Among the five machine learning algorithms, the algorithm that best predicts the putting direction was the Light GBM algorithm. When the model predicted the putting direction, the variable that had the greatest influence was the left-right inclination (Roll).

• Clinics in Shoulder and Elbow
• /
• v.23 no.1
• /
• pp.41-47
• /
• 2020

Ulnar collateral ligament injuries have been increasingly common in overhead throwing athletes. Ulnar collateral ligament reconstruction is the current gold standard for managing ulnar collateral ligament insufficiency, and numerous reconstruction techniques have been described. Although good clinical outcomes have been reported regarding return to sports, there are still several technical issues including exposure, graft selection and fixation, and ulnar nerve management. This review article summarizes a variety of surgical techniques of ulnar collateral ligament reconstructions and compares clinical outcomes and biomechanics.

• Korean Journal of Applied Biomechanics
• /
• v.24 no.3
• /
• pp.259-267
• /
• 2014

The purpose of this study was to find the relationship between standing posture biomechanics and physical fitness in the elderly. Physical fitness variables and postural variables for 227 (140 women and 87 men) elderly individuals were tested. Physical fitness tests (Korean Institute of Sports Science, 2012) included 3m sit, walk, and return, grip test, 30 second chair sit and stand, sit and reach, figure 8 walks, and 2 minute stationary march. Postural biomechanics variables included resting calcaneal stance position (RCSP), shoulder slope, pelvic slope, knee flexion angle, leg length difference, thoracic angle, and upper body slope. In statistical analysis, multiple regression was conducted by using stepwise selection method via SAS (version 9.2). Analysis for both men and women revealed significant relationships between physical fitness and age, upper body slope, knee flexion angle, leg length difference. Pelvic and thoracic angle were only related to figure 8 walking and sit and reach in women, while RCSP and shoulder slope had no relationship with any physical fitness variables.

• Korean Journal of Applied Biomechanics
• /
• v.27 no.3
• /
• pp.219-227
• /
• 2017

Objective: The aim of this study was to analyze the effects of bobsleigh shoes on the lower extremity range of motion and start speed lap time and to develop bobsleigh shoes suitable for winter environments and Korean players based on sports science and optimized biomechanical performance. Background: The bobsleigh shoes used in the start section of the sport are one of the most important equipment for improving athletes' performances. Despite the importance of the start section, there are no shoes that are specifically designed for Korean bobsleigh athletes. Thus, Korean athletes have to wear sprint spike shoes instead of bobsleigh shoes to practice the start. Method: The subjects included four bobsleigh athletes from the Gangwon Province Bobsleigh Skeleton Federation. The study selected the bobsleigh shoe type A (company A) and type B (company B). We analyzed the lower extremity range of motion and sprint time (start line to 10 m) using a Motion Analysis System (USA). Results: In the measurement of the time required for the bobsleigh start section (10 m), the type A shoes demonstrated the fastest section record by $2.765{\pm}0.086sec$ and yielded more efficient movements, hip and knee flexion, hip extension, ankle dorsiflexion, plantar flexion, and inversion than the type B shoes. Conclusion: Type A shoes can yield a better performance via effective lower extremity movements in the bobsleigh start section. Application: In the future, functional analysis should be conducted by comparing the upper material properties, comfort, and muscle fatigue of bobsleigh shoes based on the Type A shoes to develop such shoes suitable for Koreans.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.2
• /
• pp.173-179
• /
• 2011

This study aims to analyse difference in biomechanical factors between dominant legs and recessive ones according to muscular imbalance during drop landing targeting talented children in sports. The subjects of the study were ten primary students who are attending to Sports Program for Talented Children organized by C university (age: $12.28{\pm}0.70$ year, height: $1.52{\pm}0.11$ m, and weight: $45.2{\pm}4.9$ kg). Strength legs were classified into dominant side and strengthless legs were classified into non-dominant legs. For three-dimensional analyses of the data collected, 6 video cameras(MotionMaster200, Visol, Korea) were used. To analyse ground reaction force, two force platforms(AMTI ORG-6, MA) were used and to analyse electromyograghy a 8-channeled wireless Noraxon Myoresearch made in USA was used at 1000 Hz for sampling. As a result, it was discovered that the dominants legs controlled knee bending motions more stably than strengthless legs as the maximum vertical ground reaction force was significantly high in dominant legs(p<.05), and joint moment of knee joints of the dominant legs was high(p<.05). Therefore, this study suggested that injury prevention program focusing on muscular balance as well as the existing sports programs for talented children should be developed based on results of the study and it is expected that the results will be useful for improvement of sports programs for talented children.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.585-593
• /
• 2011

The purpose of this study was to analyze, from a kinematical point of view, the high jump techniques of three women's high jump winners at the IAAF World Championships, Daegu 2011. The trends for the techniques of the world's top high jumpers were examined, with a view toward adapting these techniques to the physical characteristics of Korean women's high jumpers. It was valuable that Di Martino, who was the shortest in height, was able to win a medal by using a single arm swing take-off technique, along with a half flexed leading leg swing to attain a deep arch and clear the bar. This showed that the world's top athletes used jumping techniques with no decrease in the run-up velocity at the take-off. Furthermore, It appeared that the knee joint angle at take-off had a direct effect on the body position at take-off (H1).

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.573-584
• /
• 2011

The purpose of this study was to perform a kinematic analysis of the high jump techniques of the three men's medalists at the 2011 IAAF Championships in Daegu (August 27-September 4, 2011). In particular, a three-dimensional coordinates method was used to analyze the last three strides before touchdown, the touchdown techniques, and the movements after takeoff toward the bar. An analysis of the, data for the biomechanical characteristics of the world's best high jumpers could contribute to an improvement in the performance of a national high jumper. The first conclusion of the data analysis was that the arm movements of the gold medalist, J. Williams, had a single arm form, whereas the arm movements of the other medalists were a double arm form. Second, the difference in the knee joint angles upon touchdown and toe-off was $10^{\circ}$. Third, J. Williams achieved his maximum CM height after takeoff (1.26 m) using the maximum flexion of his knee joint. Fourth, the foot contact duration of A. Dmitrik (0.11 s) was the shortest among the medalists, and the ratio for his transformation of horizontal velocity to vertical velocity was the greatest (75.25%) among the three. Last, the maximum CM height of T. Barry was the greatest, and his foot contact duration was the longest.