Korean Journal of Sport Biomechanics最新文献

{"title":"Calculation and Comparison of Maximum Lyapunov Exponent in Different Direction: An Approach to human Gait Stability","authors":"P. Dinesh","doi":"10.5103/KJSB.2021.31.1.24","DOIUrl":"https://doi.org/10.5103/KJSB.2021.31.1.24","url":null,"abstract":"Objective: The goal of this study is to calculate and compare the Maximum Lyapunov Exponent (MLE) for the anteroposterior, mediolateral and vertical displacement of the markers attached to bony land marks of the trunk and foot.\u0000Method: Ten young and healthy male subjects (age: 26.5±3.27 years, height: 167.44±5.12 cm, and weight 69.5±7.36) participated in the study. Three-dimensional positional coordinate of eight different trunk and foot marker during walking on tread mill were analysed.\u0000Results: MLE values for anteroposterior displacement of the marker were found to be significantly different with MLE values for mediolateral and vertical displacement whereas MLE values for mediolateral displacement of the marker shows no significant difference with the MLE values for vertical displacement of the markers at significance level 0.05.\u0000Conclusion: Finding of this study suggest that it is essential to consider the displacement in all three direction to examine the real characteristic of a gait signal.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116542338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinematic Analysis of Back Somersault Pike According to Skill Level in Platform Diving","authors":"Jiho Park, Sukhoon Yoon","doi":"10.5103/KJSB.2017.27.3.157","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.157","url":null,"abstract":"Objective: The purpose of this study was to investigate kinematic differences in back pike somersault in platform diving according to skill level and to apply the findings to improve performance. \u0000Method: Korean divers participating in this study were divided into a skilled group (age: 21.6±4.16 y, height: 1.68±0.03 m, weight: 62.0±3.94 kg, career: 12.6±5.13 y) and a less-skilled group (age: 20.6±2.7 y, height: 1.72±0.05 m, weight: 64.8±6.76 kg, career: 12.2±2.49 y) and an independent t-test was performed to analyze differences between groups at the moment of takeoff. \u0000Results: The two groups showed significant differences in displacement and velocity of center of mass (COM), takeoff angle, hip joint angle, knee joint angular velocity, and hip joint angular velocity at the takeoff (p<.05), and significant differences in displacement of COM, hip joint, and ankle joint during flight (p<.05). \u0000Conclusion: For a successful back pike, the COM should rise quickly in the vertical direction and the hip joint angle and angular velocity should increase. To improve performance, the back pike turn should be practiced on the ground before an attempt on a 10-m platform, to stretch the ankle and knee joints and enable quick flexion of the hip joint when turning in flight.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128774717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison Kinematic Patterns between the Star Excursion Balance Test and Y-Balance Test in Elite Athletes","authors":"J. Ko","doi":"10.5103/KJSB.2017.27.3.165","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.165","url":null,"abstract":"Objective: The Star Excursion Balance Test (SEBT) and Y-Balance Test (YBT) have been commonly applied to measure dynamic postural stability ability. These two tests are utilized interchangeably in various settings. However, they could in fact require different movements to assess dynamic postural stability, as one uses a platform and different measuring techniques than the other. The purpose of this study was to determine if there was a significant difference in the kinematic patterns in physically active population while performing the SEBT and the YBT. \u0000Method: Seventy participants performed in the Anterior (AN), Posteromedial (PM), and Posterolateral (PL) directions of the SEBT and the YBT. The kinematics of hip, knee, and ankle in sagittal plane was calculated and analyzed. Paired-sample t-tests were performed to compare joint angular displacement in the ankle, knee, and hip between the SEBT and the YBT. \u0000Results: Significant differences in angular displacement at the hip, knee, and ankle joints in the sagittal plane between performance on the SEBT and on the YBT were observed. \u0000Conclusion: Clinicians and researchers should not apply these dynamic postural control tasks interchangeably from one task to another. There appear to be kinematic pattern differences between tests in healthy physical active population.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131964411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Foot Landing Type on Lower-extremity Kinematics, Kinetics, and Energy Absorption during Single-leg Landing","authors":"Ji-Man Jeong, Choongsoo S. Shin","doi":"10.5103/KJSB.2017.27.3.189","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.189","url":null,"abstract":"Here, landing type is divided into forefoot landing, in the toes the ground first, rearfoot landing, in which the heel touches the ground first. A previous study analyzed video of ACL injuries during athletic competition found that athletes landed rearfoot at the time of injuries, and reported that rearfoot landing Objective: The aim of this study was to examine the effect of foot landing type (forefoot vs. rearfoot landing) on kinematics, kinetics, and energy absorption of hip, knee, and ankle joints. Method: Twenty-five healthy men performed single-leg landings with two different foot landing types: forefoot and rearfoot landing. A motion-capture system equipped with eight infrared cameras and a synchronized force plate embedded in the floor was used. Three-dimensional kinematic and kinetic parameters were compared using paired two-tailed Student's t -tests at a significance level of .05. Results: On initial contact, a greater knee flexion angle was shown during rearfoot landing ( p < .001), but the lower knee flexion angle was found at peak vertical ground reaction force (GRF) ( p < .001). On initial contact, ankles showed plantarflexion, inversion, and external rotation during forefoot landing, while dorsiflexion, eversion, and internal rotation were shown during rearfoot landing ( p < .001, all). At peak vertical GRF, the knee extension moment and ankle plantarflexion moment were lower in rearfoot landing than in forefoot landing ( p = .003 and p < .001, respectively). From initial contact to peak vertical GRF, the negative work of the hip, knee, and ankle joint was significantly reduced during rearfoot landing ( p < .001, all). The contribution to the total work of the ankle joint was the greatest during forefoot landing, whereas the contribution to the total work of the hip joint was the greatest during rearfoot landing. Conclusion: These results suggest that the energy absorption strategy was changed during rearfoot landing compared with forefoot landing according to lower-extremity joint kinematics and kinetics.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124523476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Kinematics and Kinetics According to Skill Level and Sex in Double-under Jump Rope Technique","authors":"Dae Young Kim, Kyeong Hui Jang, Myeounggon Lee, M. Son, You Kyung Kim, Jin-Heem Kim, C. Youm","doi":"10.5103/KJSB.2017.27.3.171","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.171","url":null,"abstract":"Jump rope is a sport in which players jump over a rope while swinging the rope with their upper body and hands to pass it under their feet and over their heads (Miyaguchi, Demura & Omoya, 2015), and is one of the most effective aerobic exercises for cardiorespiratory health (Jones, Squires & Rodahl, 1962). Neuromuscular coordination is essential for accurate timing and maintenance of rhythm, which are critical for effective jump rope performance, and good neuromuscular coordination improves dynamic stability while performing jump rope (Ozer, Duzgun, Baltaci, Garacan & Colakoglu, 2011). Furthermore, jump rope effectively enhances muscle strength, endurance, balance, explosive power, speed, cardiopulmonary endurance, and flexibility, and is therefore used as a warm-up exercise and training program in various sports (Hawkins & Kennedy, 1980; Orhan, 2013; Solis & Thompson, 1988; Trampas & Kitisios, 2006). Jump rope is an essential component of professional training programs designed to enhance athletic performance by elite junior athletes, and several studies have reported beneficial effects on physical fitness, growth, and development in these athletes (Baker, Côté & Abernethy, 2003; Miyaguchi, Sugiura & Demura, 2014). Elite athletes often use plyometric training programs with box jumps or hurdle jumps to improve explosive power and jump performance (Komi, 1984). However, these training programs inflict a heavy load on elite junior athletes who are still undergoing physical development, and increase their risk of injury (Komori, Zushi, Konishi & Komori, 2012). For this reason, it is important to develop alternative training programs that offer effective training with a relatively low risk of injury. Jump rope is one such alternative. Jump rope has the properties of plyometric exercise, as the sport involves repeated contractions and extensions of the quadriceps femoris, gastrocnemius, and soleus muscles, thereby improving explosive power and jumping ability (Komi, 1984; Norman & Komi, 1979; Miyaguchi et al., 2014, 2015). Accordingly, jump rope is utilized in training programs for a variety of other sports, such as volleyball, basketball, soccer, gymnastics, rhythmic gymnastics, boxing, wrestling, tennis, and martial arts (Ozer et al., 2011; Trecroci, Cavaggioni, Caccia & Alberti, 2015). Korean Journal of Sport Biomechanics 2017; 27(3): 171-179 http://dx.doi.org/10.5103/KJSB.2017.27.3.171 http://e-kjsb.org eISSN 2093-9752 ORIGINAL","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128488065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Professional Body Massage on Forward Head Posture, Neck Pain, and Plantar Foot Pressure Balance in Men in their 20s","authors":"Soon-Seob Jang, J. Lee, Jeongok Yang, Bom-jin Lee, Eui-Suk Kim, Kyung-Hee Woo, Se-Jin Oh","doi":"10.5103/KJSB.2017.27.3.211","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.211","url":null,"abstract":"Due to the development of IT devices, the number of people using smartphones in present days is continuously increasing. The usage rate of smartphones has increased from 27% in 2011 to 78.8% in 2015 (Korea Communications Commission, 2015), and the number of patients with \"turtle neck syndrome\" is increasing rapidly. According to the Health Insurance Review and Assessment Service (2015), the number of patients with cervical neck disease increased 16.6% from 2,270,000 in 2011 to 2,650,000 in 2015, among which the number of people diagnosed with turtle neck syndrome increased twofold in 4 years from 606 in 2011 to 1,134 in 2015. Based on the result of the survey on the \"utilization rate of smartphone by age,\" people in their 20s took the first place with 96.4% (Health Insurance Review and Assessment Service, 2012), and the average daily usage time of smartphone by Koreans was 3 h per person. People in their 20s had the longest average daily usage time of 4 h per day (Lim, 2016). The turtle neck syndrome is a symptom in which the cervical bone is deformed into \"1\" or inverted letter \"C\" shape. Healthy cervical neck bones have the appearance of a well-curved C shape, which could be deformed if an individual’s neck is bent forward for a long time (Jeon, 2016). The turtle neck posture appears to be due to physical imbalance from maintaining a wrong posture for a long period (Hwang, 2012). Habits of maintaining wrong posture can cause deformity of the spine that causes pain and difficulty in having a healthy daily life (Im, 2003). In this way, our body parts such as the shoulder, waist, pelvis, and knee center around the vertebrate to maintain left and right symmetry of the whole body. Therefore, failure to maintain proper posture can lead to physical imbalance (Oh, 2016). Physical imbalance due to poor posture such as having the pelvis twisted to one side or the body tilted to one side can break the overall balance of the whole body and cause pain (Kim, 2013; Son, 2014; Woo, 2014; Park, 2015; Oh, 2016). A well-balanced posture affects the coordination of various joints such as upper and lower skeletal muscles and gait. Foot balance is important because it directly affects the ability to walk and increases body stability (Choi & No, 2011). This demonstrates that body balance and foot balance are Korean Journal of Sport Biomechanics 2017; 27(3): 211-217 http://dx.doi.org/10.5103/KJSB.2017.27.3.211 http://e-kjsb.org eISSN 2093-9752 ORIGINAL","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125522291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the Dynamic Balance Recovery Ability by External Perturbation in the Elderly","authors":"Da Won Park, K. Koh, Y. Park, J. Shim","doi":"10.5103/KJSB.2017.27.3.205","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.205","url":null,"abstract":"Objective: The aim of the study was to investigate the age-related ability of dynamic balance recovery through perturbation response during standing. \u0000Method: Six older and 6 younger adults participated in this study. External perturbation during standing as pulling force applied at the pelvic level in the anterior direction was provided to the subject. The margin of stability was quantified as a measure of postural stability or dynamic balance recovery, and using principal component analysis (PCA), the regularity of the margin of stability (MoS) was calculated. \u0000Results: Our results showed that in the older adult group, 60.99% and 28.63% of the total variance were captured using the first and second principal components (PCs), respectively, and in the younger adult group, 81.95% and 10.71% of the total variance were captured using the first and second PCs, respectively. \u0000Conclusion: Ninety percent of the total variance captured using the first two PCs indicates that the older adults had decreased regularity of the MoS than the younger adults. Thus, the results of the present study suggest that aging is associated with non-regularity of dynamic postural stability.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127294233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Factors on Response Variables Lap Time and Lower Extremity Range of Motion in Bobsleigh Start using Bobsleigh Shoes for the 2018 PyeongChang Winter Olympics","authors":"Seung-bum Park, Kyungdeuk Lee, Daewoong Kim, Jung-Hyeon Yoo, Jae-Hu Jung, Kyunghwan Park","doi":"10.5103/KJSB.2017.27.3.219","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.219","url":null,"abstract":"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. \u0000Background: 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. \u0000Method: 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). \u0000Results: 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±0.086 sec and yielded more efficient movements, hip and knee flexion, hip extension, ankle dorsiflexion, plantar flexion, and inversion than the type B shoes. \u0000Conclusion: Type A shoes can yield a better performance via effective lower extremity movements in the bobsleigh start section. \u0000Application: 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.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114979617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Analysis on the Variations of Ground Reaction Force during Ascent and Descent of Bus Stairs in Women","authors":"Seung-Hyun Hyun, Che-Cheong Ryew","doi":"10.5103/KJSB.2017.27.3.181","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.181","url":null,"abstract":"force has close relation with vertical height of stair during stair gait, as usual bus for public transportation has higher height of stair than that of the others of building, tracking & climb course, vehicles etc.. Stair standard of domestic bus's vertical height of bus showed 27.00±1.32 cm of 1st, 26.50±2.17 cm of 2nd stair, and 37.66±0.28 cm of 3rd stair on the basis of descending (Ryew & Hyun, 2013). Also if lined up at designated bus stoppage exactly, stair height of 19.66 cm was rather higher slightly than 18 cm of architectural standard (Yoon, 2008) except for vertical height (18 cm) of side walk block, Objective: The aim of the study was to compare & analyze on the variations of ground reaction force during ascending and descending of bus stair. Method: Simulated wooden stair of bus (raiser: 37.66 cm, width: 109 cm, tread: 29 cm) and GRF system (AMTI-OR-7/ AMTI., USA) was set up within experimental room. Adult female (n=8) performed ascending & descending of simulated bus stair, and variables analyzed consisted of TT (transfer-time), PVF (peak vertical force), LR (loading rate), DR (decay rate), CV (coefficient of variation) and AI (asymmetry index). Sample data from GRF cut off at 1,000 Hz. Results: TT showed shortest variation at phase 1 during descending, but longest variation at phase 1 during ascending of stair. PVF19 (Fz2, 100%) showed large pattern during descending than that of ascending, but rather showed small pattern during ascending of stair in case of PVF2 (Fz4). LR showed larger pattern during descending than that of ascending, but rather during ascending of stair in case of DR. Variation of CV (%) did not show difference between LR and DR, but showed higher possible occurrence of variation during descending of stair. Also AI (%) showed higher index during ascending than that of descending of stair. Conclusion: Because introduction of lowered bus stair has various realistic problems, if lined up at designated bus stopage exactly, rather can solve problems of inconvenience, reduce impulsive force and secure a stability of COG during ascending & descending of stair.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126725546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Exercise Intensity on Muscle Activity and Kinematic Variables of the Lower Extremity during Squat","authors":"Jae-Hu Jung, W. Chae","doi":"10.5103/KJSB.2017.27.3.197","DOIUrl":"https://doi.org/10.5103/KJSB.2017.27.3.197","url":null,"abstract":"Objective: The purpose of this study was to determine how exercise intensity affects muscle activity and kinematic variables during squat. Method: Fifteen trainers with >5 years of experience were recruited. For the electromyography (EMG) measurements, four surface electrodes were attached to bot...","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129738979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}