Korean Journal of Sport Biomechanics最新文献

{"title":"A Comparative Analysis of Biomechanical Factors and Premotor Time of Body Muscles between Elite College and Amateur Baseball Players during the Baseball Batting Motion","authors":"Y. Lim, Moonseok Kwon","doi":"10.5103/KJSB.2016.26.2.205","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.205","url":null,"abstract":"Purpose: The aim of this study was to analyze biomechanical factors and PMT (premotor time) of bodymuscles between elite college and amateur baseball players during the baseball batting motion.Method: Kinematic and electromyographic data were obtained for 10 elite college baseball players and 10amateur baseball players who participated in this study. All motion capture data were collected at 200 Hzusing 8 VICON cameras and the PMT of muscles was recorded using a Delsys Trigno wireless system. Thepeak mean bat speed and the peak mean angular velocities of trunk, pelvis, and bat with PMT of 16 bodymuscles were computed. These kinematic and PMT data of both groups were compared by independentt-tests (p < .05).Results: The pelvis, trunk, and bat showed a sequence of angular velocity value during baseball batting.The PMTs of right tibialis anterior, left gastrocnemius, external oblique, and erector spinae were significantlydifferent between the two groups.Conclusion: The PMT of body muscles was related to the shifting of body and rotation of the pelvis andthe trunk segment, and this action can be considered the coordinated muscle activity of the lower andupper body.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"301 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115929426","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":"A Correlational Study of Biomechanical Variables and Aesthetic Artistry in Grand Pas de Chat","authors":"Jung-Eun Jung, Kyung-Ill Lee","doi":"10.5103/KJSB.2016.26.2.183","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.183","url":null,"abstract":"The goal of jumping is to jump vertically as high as possible using one foot or both feet (Park, 2005). Of jumping movements in ballet, grand pas de chat, a technique that appears in many ballet performances, requires a high skill level. In grand pas de chat, following various preparation steps, the dancer throws the jumping leg forward, lifting it more than 90°, stretches the other leg backward in synchrony with power with two legs stretched in opposite directions as maximally as possible, and then lands on one leg. During the movement, the upper body should show soft, artistic expression, in contrast to the powerful legs, and a straight posture should be maintained until the completion of the jump. This jumping technique requires coordination among various body segments, and should be performed by effectively controlling the energy generated in each of the involved joints. In particular, lower limb muscle strength, as well as flexibility, can be an indicator of the ability to perform jumping movements in ballet with excellence, affecting the time in the air during the jump and the vertical height of the jump. Therefore, in order to improve ballet performance, it is very important for ballet dancers to strengthen the lower limb muscles. In ballet, the goal of body training is to develop interdependence among posture, balance, and harmonious movement, which is considered as the most crucial factor in aesthetics (Lee, 2000; Shim, 2004). Ballet dancers are increasingly practicing pilates or using fitness equipment for body training in order to efficiently develop ballet skills. Such exercises help ballet dancers not only with flexibility but also with muscle strengthening. To better enable ballet dancers to improve ballet skills through physical exercise training, it is necessary to provide ballet dancers with basic data on fundamental training approaches. Until now, kinematic studies on dancing movements have been only intermittently conducted. Of the studies conducted so far, Yoon (2010) has reported that the grand pas de chat movement is influenced by the type of running start, and that a forward jump using inertia is a crucial factor for grand pas de chat. In addition, Sin, Song and Choi (2009) conducted kinematic analysis on ballerinos' jumping motions and stressed the importance of the displacement of the center of gravity. Such studies as these are of significance because they not only examine techniques but also emphasize artistry. The aforementioned studies demonstrate that in dancing, jumping is not only a technique but also KJSB Korean Journal of Sport Biomechanics 2016; 26(2): 183-190 http://dx.doi.org/10.5103/KJSB.2016.26.2.183 http://e-kjsb.org eISSN 2093-9752 ORIGINAL","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125511793","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 of Lower Extremity Kinematics and Kinetics during Downhill and Valley-shape Combined Slope Walking","authors":"Ji-Man Jeong, Choongsoo S. Shin","doi":"10.5103/KJSB.2016.26.2.161","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.161","url":null,"abstract":"Objective: The purpose of this study was to determine the knee and ankle joint kinematics and kinetics by comparing downhill walking with valley-shape combined slope walking. Method: Eighteen healthy men participated in this study. A three-dimensional motion capture system equipped with eight infrared cameras and a synchronized force plate, which was embedded in the sloped walkway, was used. Obtained kinematic and kinetic parameters were compared using paired two-tailed Student ' s t -tests at a significance level of 0.05. Results: The knee flexion angle after the mid-stance phase, the mean peak knee flexion angle in the early swing phase, and the ankle mean peak dorsiflexion angle were greater during downhill walking compared with valley-shape combined slope walking ( p < 0.001). Both the mean peak vertical ground reaction force (GRF) in the early stance phase and late stance phase during downhill walking were smaller than those values during valley-shape combined slope walking. ( p = 0.007 and p < 0.001, respectively). The mean peak anterior GRF, appearing right after toe-off during downhill walking, was also smaller than that of valley-shape combined slope walking ( p = 0.002). The mean peak knee extension moment and ankle plantar flexion moment in late stance phase during downhill walking were significantly smaller than those of valley-shape combined slope walking ( p = 0.002 and p = 0.015, respectively). Conclusion: These results suggest that gait strategy was modified during valley-shape combined slope walking when compared with continuous downhill walking in order to gain the propulsion for lifting the body up the incline for foot clearance.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116775068","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":"Differences in the Joint Movements and Muscle Activities of Novice according to Cycle Pedal Type","authors":"Jeongwoo Seo, Daehyeok Kim, S. Yang, D. Kang, Jin-Seung Choi, Jinwoo Kim, G. Tack","doi":"10.5103/KJSB.2016.26.2.237","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.237","url":null,"abstract":"Objective: The purpose of this study was to compare the joint movements and muscle activities of novicesaccording to pedal type (flat, clip, and cleat pedal).Method: Nine novice male subjects (age: 24.4 ± 1.9 years, height: 1.77 ± 0.05 m, weight: 72.4 ± 7.6 kg, shoesize: 267.20 ± 7.50 mm) participated in 3-minute, 60-rpm cycle pedaling tests with the same load andcadence. Each of the subject’s saddle height was determined by the 155° knee flexion angle when the pedalcrank was at the 6 o``clock position (25° knee angle method). The muscle activities of the vastus lateralis,tibialis anterior, biceps femoris, and gastrocnemius medialis were compared by using electromyographyduring 4 pedaling phases (phase 1: 330~30°, phase 2: 30~150°, phase 3: 150~210°, and phase 4: 210~330°).Results: The knee joint movement (range of motion) and maximum dorsiflexion angle of the ankle jointwith the flat pedal were larger than those of the clip and cleat pedals. The maximum plantarflexion timingwith the flat and clip pedals was faster than that of the flat pedal. Electromyography revealed that thevastus lateralis muscle activity with the flat pedal was greater than that with the clip and cleat pedals.Conclusion: With the clip and cleat pedals, the joint movements were limited but the muscle activitieswere more effective than that with the flat pedal. The novice cannot benefit from the clip and cleat pedalsregardless of their pull-up pedaling advantage. Therefore, the novice should perform the skilled pullinguppedaling exercise in order to benefit from the clip and cleat pedals in terms of pedaling performance.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126840036","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 Joint Mobilization on Foot Pressure, Ankle Moment, and Vertical Ground Reaction Force in Subjects with Ankle Instability","authors":"N. Yoon, Yeon-Soon Seo, Y. Kang","doi":"10.5103/KJSB.2016.26.2.153","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.153","url":null,"abstract":"Objective: The purpose of this study was to investigate the effects of joint mobilization on foot pressure,ankle moment, and vertical ground reaction force in subjects with ankle instability.Method: Twenty male subjects (age, 25.38 ± 3.62 yr; height, 170.92 ± 5.41 cm; weight, 60.74 ± 9.63 kg;body mass index (BMI), 19.20 ± 1.67 kg/m2) participated and underwent ankle joint mobilization. Weightbearingdistribution, ankle dorsi/plantar flexion moment, and vertical ground reaction force were measuredusing a GPS 400 and a VICON Motion System (Oxford, UK), and subsequently analyzed. SPSS 20.0 forWindows was used for data processing and paired t-tests were used to compare pre- and post-mobilizationmeasurements. The significance level was set at α = .05.Results: The results indicated changes in weight-bearing, ankle dorsi/plantar flexion moment, and verticalground reaction force. The findings showed changes in weight-bearing distribution on the left (pre 29.51± 6.31 kg, post 29.57 ± 5.02 kg) and right foot (pre 32.40 ± 6.30 kg, post 31.18 ± 5.47 kg). There weresignificant differences in dorsi/plantar flexion moment (p < .01), and there were significant increases invertical ground reaction forces at initial stance (Fz1) and terminal stance (Fz2, p < .05). Additionally, therewas a significant reduction in vertical ground reaction force at midstance (Fz2, p < .001).Conclusion: Joint mobilization appears to alter weight-bearing distribution in subjects with ankle instability,with resultant improvements in stability.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129038796","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 Fatigue Induction on Ground Reaction Force Components, Postural Stability, and Vertical Jump Performance in Taekwondo Athletes","authors":"Seung-Hyun Hyun, Young Pyo Kim, Che-Cheong Ryew","doi":"10.5103/KJSB.2016.26.2.143","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.143","url":null,"abstract":"Objective: The purpose of this study was to investigate the effect of fatigue induction on ground reactionforce (GRF) components, postural stability, and vertical jump performance in Taekwondo athletes.Method: Ten Taekwondo athletes (5 men, 5 women; mean age, 22.30 ± 2.62 years; mean height, 174.21 ±9.20 cm; mean body weight, 67.28 ± 12.56 kg) participated in this study. Fatigue was induced by a shortperiod of strenuous exercise performed on a motorized treadmill. The analyzed variables included verticaljump performance, static stability (mediolateral [ML], center of pressure [COP], anteroposterior [AP] COP,ΔCOPx, ΔCOPy, and COP area), postural stability index values (ML stability index [MLSI], AP stability index[APSI], vertical stability index [VSI], dynamic postural stability index [DPSI]), and GRF components (MLforce, AP force, peak vertical force [PVF], and loading rate). To analyze the variables measured in this study,PASW version 22.0 was used to calculate the mean and standard deviation, while a paired t-test was usedto evaluate the pre- versus post-fatigue results. Pearson``s correlation coefficients among variables were alsoanalyzed. The statistical significance level was set at α = .05.Results: Vertical jump performance decreased significantly after the induction of fatigue, while AP COP,ΔCOPx, COP area, APSI, VSI, and DPSI increased significantly. PVF and loading rate increased significantlyafter the induction of fatigue, while the postural stability variables (AP COP, ΔCOPy, COP area, APSI, VSI,DPSI) were similarly correlated with GRF components (PVF, loading rate) after fatigue was achieved (r= .600, R2 = 37%).Conclusion: These results suggest that the induction of fatigue can decrease postural stability and exerciseperformance of Taekwondo athletes during training and competition sessions.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115351037","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":"Relationship between Attenuation of Impact Shock at High Frequency and Flexion-Extension of the Lower Extremity Joints during Downhill Running","authors":"Jiseon Ryu, Sukhoon Yoon, Sang-Kyoon Park","doi":"10.5103/KJSB.2016.26.2.167","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.167","url":null,"abstract":"Objective: The purpose of this study was to determine the interrelationship between ranges of motion ofthe knee and ankle joints on the sagittal plane and the attenuation magnitude of impact shock at highfrequency (9~20 Hz) in the support phase during downhill running.Method: Fifteen male heel-toe runners with no history of lower extremity injuries were recruited for thisstudy (age, 25.07 ± 5.35 years; height, 175.4 ± 4.6 cm; mass, 75.8 ± .70 kg). Two uniaxial accelerometers weremounted to the tuberosity of tibia and sacrum, respectively, to measure acceleration signals. The participantswere asked to run at their preferred running speed on a treadmill set at 0°, 7°, and 15° downhill. Sixoptical cameras were placed around the treadmill to capture the coordinates of the joints of the lowerextremities. The power spectrum densities of the two acceleration signals were analyzed and used in thetransfer function describing the gain and attenuation of impact shock between the tibia and the sacrum.Angles of the knee and ankle joints on the sagittal plane and their angle ranges were calculated. ThePearson correlation coefficient was used to test the relationship between two variables, the magnitude ofimpact shock, and the range of joint angle under three downhill conditions. The alpha level was set at .05.Results: Close correlations were observed between the knee joint range of motion and the attenuationmagnitude of impact shock regardless of running slopes (p<.05), and positive correlations were foundbetween the ranges of motion of the knee and ankle joints and the attenuation magnitude of impact shockin 15° downhill running (p<.05).Conclusion: In conclusion, increased knee flexion might be required to attenuate impact shock duringdownhill and level running through change in stride or cadence while maintaining stability, and strongand flexible ankle joints are also needed in steeper downhill running.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131125520","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":"Development of Core Strength Training Equipment and Its Effect on the Performance and Stability of the Elderly in Activities of Daily Living","authors":"K. Koh, Y. Park, Da Won Park, C. Hong, J. Shim","doi":"10.5103/KJSB.2016.26.2.229","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.2.229","url":null,"abstract":"The Movement Science Center of Research Institute for Sports Science and Sports Industry, Hanyang University, Seoul, South Korea Department of Physical Education, College of Performing Arts and Sports, Hanyang University, Seoul, South Korea Department of Kinesiology, University of Maryland, College Park, MD, USA Guemgang University, Nonsan, South Korea Department of Mechanical Engineering, Kyunghee University, Global Campus, Kyung-gi, South Korea Fischell Department of Bioengineering/Neuroscience and Cognitive Science (NACS) Program, University of Maryland, College Park, MD, USA","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122221096","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":"Analyses of Plantar Foot Pressure and Static Balance According to the Type of Insole in the Elderly","authors":"Kang-Ho Bae, J. Shin, J. Lee, Jeongok Yang, Bom-jin Lee, Seung-bum Park","doi":"10.5103/KJSB.2016.26.1.115","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.1.115","url":null,"abstract":"Methods: Thirteen elderly (mean age: 67.08±2.25 years, mean height: 159.63±9.64 cm, mean body weight: 61.48±9.06 kg) who had no previous injury experience in the lower limbs and a normal gait pattern participated in this study. Three models of insoles of the normal, 3D, and triangle types were selected for the test. The Pedar-X system and PedarX insoles, 3.3 km/h of walking speed, and a compilation of 20 steps walking stages were used to analyze foot-pressure distribution. Static balance test was conducted using Gaitview AFA-50, and balance (opening eyes, closing eyes) was inspected for 20 s. Oneway ANOVA was conducted to test the significance of the results with the three insoles. P-value of less than .05 was considered statistically significant.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124222957","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":"Acute Changes in Fascicle Behavior and Electromyographic Activity of the Medial Gastrocnemius during Walking in High Heeled Shoes","authors":"Jin-sun Kim, Hae-Dong Lee","doi":"10.5103/KJSB.2016.26.1.135","DOIUrl":"https://doi.org/10.5103/KJSB.2016.26.1.135","url":null,"abstract":"Corresponding Author Hae-Dong Lee Department of Physical Education, College of Sciences in Education, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Korea Tel : +82-2-2123-6188 Fax : +82-2-2123-8375 Email : xbridge1997@ yonsei.ac.kr Objective: The purpose of this study was to investigate the acute effect of walking on high heels on the behavior of fascicle length and activation of the lower limb muscles.","PeriodicalId":306685,"journal":{"name":"Korean Journal of Sport Biomechanics","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133545783","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}