检索结果-内蒙古大学图书馆

Interlimb Force Coordination in Bipedal Dance Jumps: Comparison Between Experts and Novices

JOURNAL OF APPLIED BIOMECHANICS 2018年第6期34卷 462-468页

作者： Shih, Hai-Jung Steffi Jarvis, Danielle N. Mikkelsen, Pamela Kulig, Kornelia Univ Southern Calif Div Biokinesiol & Phys Therapy Los Angeles CA 90007 USA Calif State Univ Northridge Dept Kinesiol Northridge CA 91330 USA Cedars Sinai Dept Phys Med & Rehabil Los Angeles CA USA

Bipedal tasks require interlimb coordination that improves with practice and acquisition of skills. The purpose of this study was to compare interlimb force coordination during dance-specific rate-controlled consecutive bipedal jumps (sautes) between expert dancers and nondancers. To analyze coordination of vertical ground reaction forces recorded under each leg, the vector coding approach was used. Although there were no differences in the patterns of interlimb force coordination between groups, the dancers exhibited less variability of interlimb force coordination during the transition phase from weight acceptance to propulsion as well as during the propulsion phase itself. The interlimb force coordination variability was associated with task performance only during the transition phase, which highlights the potential importance of control during this phase. In conclusion, expert dancers were better at reducing interlimb force coordination variability during the task-relevant transition phase, which was related to better performance at maintaining jump rate and jump height consistency.

关键词： variability vector coding motor control lower extremity

来源：评论

学校读者我要写书评

暂无评论

Intratrunk Coordination During High-Effort Treadmill Running in Individuals With Spinal Fusion for Adolescent Idiopathic Scoliosis

引用

JOURNAL OF APPLIED BIOMECHANICS 2017年第6期33卷 437-445页

作者： Li, Yumeng Kakar, Rumit S. Walker, Marika A. Fu, Yang-Chieh Oswald, Timothy S. Brown, Cathleen N. Simpson, Kathy J. Calif State Univ Chico Dept Kinesiol Chico CA 95929 USA Ithaca Coll Dept Phys Therapy Ithaca NY 14850 USA Univ Georgia Dept Kinesiol Athens GA 30602 USA Univ Mississippi Dept Hlth Exercise Sci & Recreat Management Oxford MS USA Pediat Orthopaed Associates Atlanta GA USA Oregon State Univ Dept Athlet Training & Kinesiol Corvallis OR 97331 USA

The purpose of the study was to determine if the intratrunk coordination of axial rotation exhibited by individuals with spinal fusion for adolescent idiopathic scoliosis (SF-AIS) during running varies from healthy individuals and how the coordination differs among adjacent trunk-segment pairs. Axial rotations of trunk segments (upper, middle, lower trunk) and pelvis were collected for 11 SF-AIS participants and 11 matched controls during running. Cross-correlation determined the phase lag between the adjacent segment motions. The coupling angle was generated using the vector coding method and classified into 1 of the 4 major, modified coordination patterns: in-phase, anti-phase, superior, and inferior phase. Two-way, mixed-model ANCOVA was employed to test phase lag, cross-correlation r, and time spent in each major coordination pattern. A significantly lower phase lag for SF-AIS was observed compared with controls. Qualitatively, there was a tendency that SF-MS participants spent less time in anti-phase for middle-lower trunk and lower trunk-pelvis coordinations compared to controls. Phase lag and anti-phase time was significantly increased from cephalic to caudal segment pairs, regardless of group. In conclusion, SF-MS participants and controls displayed similar patterns of intra-trunk coordination;however, the spinal fusion hindered decoupling of intra-trunk motions particularly between the lower trunk-pelvic motion.

关键词： intersegmental coordination locomotion kinematics spine trunk vector coding

来源：评论

学校读者我要写书评

暂无评论

Comparison of Transverse Plane Tibial and Frontal Plane Rearfoot Motion and Movement Coordination Between Runners With Medial Tibial Stress Syndrome and Healthy Controls

引用

JOURNAL OF APPLIED BIOMECHANICS 2020年第6期36卷 375-380页

作者： Langley, Ben Knight, Nick Morrison, Stewart C. Edge Hill Univ Dept Sport & Phys Act Ormskirk Lancs England NK Act Basingstoke Hants England Univ Brighton Sch Hlth Sci Brighton E Sussex England

Medial tibial stress syndrome (MTSS) is a common running-related injury. Alterations in movement patterns and movement coordination patterns have been linked to the development of overuse injuries. The aim of this study was to compare transverse plane tibial and frontal plane rearfoot motion and the coordination of these movements between runners with MTSS and healthy controls. A total of 10 recreational runners with MTSS and 10 healthy controls ran at 11 km/h on a treadmill. A 3-camera motion analysis system operating at 200 Hz was used to calculate tibia and rearfoot motion. Stance phase motion patterns were compared between groups using multivariate analysis, specifically, Hotelling T-2 test with statistical parametric mapping. A modified vector coding technique was used to classify the coordination of transverse plane tibial and frontal plane rearfoot motion. The frequency of each coordination pattern displayed by each group was compared using independent samples t tests. Individuals with MTSS displayed significantly (P = .037, d= 1.00) more antiphase coordination (tibial internal rotation with rearfoot inversion) despite no significant (P> .05) differences in stance phase kinematics. The increased antiphase movement may increase the torsional stress placed upon the medial aspect of the tibia, contributing to the development of MISS.

关键词： running injury vector coding statistical parametric mapping kinematics

来源：评论

学校读者我要写书评

暂无评论

Efficient disparity vector prediction schemes with modified P frame for 2D camera arrays

引用

JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2012年第2期23卷 287-292页

作者： Avci, Aykut De Cock, Jan Lambert, Peter Beernaert, Roe De Smet, Jelle Bogaert, Lawrence Meuret, Youri Thienpont, Hugo De Smet, Herbert Univ Ghent Ctr Microsyst Technol Dept Elect & Informat Syst B-9052 Ghent Belgium Univ Ghent IBBT Dept Elect & Informat Syst Multimedia Lab B-9050 Ledeberg Ghent Belgium Vrije Univ Brussel Brussels Photon Team B-1050 Brussels Belgium IMEC Ctr Microsyst Technol B-9052 Ghent Belgium

An efficient disparity estimation algorithm for multi-view video sequences, recorded by a two-dimensional camera array in which the cameras are spaced equidistantly, is presented. Because of the strong geometrical relationship among views, the disparity vectors of a certain view can for most blocks be derived from the disparity vectors of other views. A frame constructed using that idea is called a D frame in this work. Three new prediction schemes which contain D frames are proposed for encoding 5 x 3 multi-view video sequences. The schemes are applied to several multi-view image sequences taken from a camera-array and they are compared in terms of quality, bit-rate and complexity. The experimental results show that the proposed prediction schemes significantly decrease the complexity of the encoder at a very low cost of quality and/or bit-rate. (C) 2011 Elsevier Inc. All rights reserved.

关键词： Multi-view Video coding Camera array Disparity vector coding Estimation Complexity Scheme Prediction H.264

来源：评论

学校读者我要写书评

暂无评论

Coupling angle variability in healthy and patellofemoral pain runners

引用

CLINICAL BIOMECHANICS 2014年第3期29卷 317-322页

作者： Cunningham, Tommy J. Mullineaux, David R. Noehren, Brian Shapiro, Robert Uhl, Timothy L. CCB Res Grp Lexington KY 40506 USA Lincoln Univ Sch Sport & Exercise Sci Lincoln England Univ Kentucky Div Phys Therapy Lexington KY 40506 USA Univ Kentucky Dept Kinesiol & Hlth Promot Lexington KY 40506 USA Univ Kentucky Div Athlet Training Lexington KY 40506 USA Univ Kentucky Coll Hlth Sci Adjunct Fac Lexington KY 40506 USA

Background: Patellofemoral pain is hypothesized to result in less joint coordination variability. The ability to relate coordination variability to patellofemoral pain pathology could have many clinical uses;however, evidence to support its clinical application is lacking. The aim was to determine if vector coding's coupling angle variability, as a measure of joint coordination variability, was less for runners with patellofemoral pain than healthy controls as is commonly postulated. Methods: Nineteen female recreational runners with patellofemoral pain and eleven healthy controls performed a treadmill acclimation protocol then ran at a self-selected pace for 15 min. 3-D kinematics, force plate kinetics, knee pain and rating of perceived exertion were recorded each minute. Data were selected for the: pain group at the highest pain reached (pain 3/10) in a non-exerted state (exertion < 14/20), and;non-exerted healthy group from the eleventh minute. Coupling angle variability was calculated over several portions of the stride for six knee-ankle combinations during five non-consecutive strides. Findings: 46 of 48 coupling angle variability measures were greater for the pain group, with 7 significantly greater (P <.05). Interpretation: These findings oppose the theory that less coupling angle variability is indicative of a pathological coordinate state during running. Greater coupling angle variability may be characteristic of patellofemoral pain in female treadmill running when a larger threshold of pain is reached than previously observed. A predictable and directional response of coupling angle variability measures in relation to knee pathology is not yet clear and requires further investigation prior to considerations for clinical utility. 2013 Elsevier Ltd. All rights reserved.

关键词： vector coding Gait Kinematics Dynamical systems Running

来源：评论

学校读者我要写书评

暂无评论

A CPU BENCHMARK FOR PROTEIN CRYSTALLOGRAPHIC REFINEMENT

引用

COMPUTERS IN BIOLOGY AND MEDICINE 1990年第4期20卷 219-230页

作者： BOURNE, PE HENDRICKSON, WA COLUMBIA UNIV HOWARD HUGHES MED INST DEPT BIOCHEM & MOLEC BIOPHYS 630 W 168TH ST NEW YORK NY 10032 USA

The CPU time required to complete a cycle of restrained least-squares refinement of a protein structure from X-ray crystallographic data using the FORTRAN codes PROTIN and PROLSQ are reported for 48 different processors, ranging from single-user workstations to supercomputers. Sequential, vector, VLIW, multiprocessor, and RISC hardware architectures are compared using both a small and a large protein structure. Representative compile times for each hardware type are also given, and the improvement in run-time when coding for a specific hardware architecture considered. The benchmarks involve scalar integer and vector floating point arithmetic and are representative of the calculations performed in many scientific disciplines.

关键词： Benchmark Compile times Crystallography Multi-processor PROTIN PROLSQ RISC vector coding vector processor VLIW

来源：评论

学校读者我要写书评

暂无评论

Using Gait Variability to Predict Inter-individual Differences in Learning Rate of a Novel Obstacle Course

引用

ANNALS OF BIOMEDICAL ENGINEERING 2019年第5期47卷 1191-1202页

作者： Ulman, Sophia Ranganathan, Shyam Queen, Robin Srinivasan, Divya Virginia Tech Dept Ind & Syst Engn Blacksburg VA 24061 USA Virginia Tech Dept Stat Blacksburg VA USA Virginia Tech Dept Biomed Engn & Mech Blacksburg VA USA

This study aimed to determine whether inter-individual differences in learning rate of a novel motor task could be predicted by movement variability exhibited in a related baseline task, and determine which variability measures best discriminate individual differences in learning rate. Thirty-two participants were asked to repeatedly complete an obstacle course until achieving success in a dual-task paradigm. Their baseline gait kinematics during self-paced level walking were used to calculate stride-to-stride variability in stride characteristics, joint angle trajectories, and inter-joint coordination. The gait variability measures were reduced to functional attributes through principal component analysis and used as predictors in multiple linear regression models. The models were used to predict the number of trials needed by each individual to complete the obstacle course successfully. Frontal plane coordination variability of the hip-knee and knee-ankle joint couples in both stance and swing phases of baseline gait were the strongest predictors, and explained 62% of the variance in learning rate. These results show that gait variability measures can be used to predict short-term differences in function between individuals. Future research examining statistical persistence in gait time series that can capture the temporal dimension of gait pattern variability, may further improve learning performance prediction.

关键词： Movement variability Kinematics Inter-joint coordination vector coding Motor learning

来源：评论

学校读者我要写书评

暂无评论

Discrete and continuous joint coupling relationships in uninjured recreational runners

引用

CLINICAL BIOMECHANICS 2007年第5期22卷 581-591页

作者： Dierks, Tracy A. Davis, Irene Indiana Univ Dept Phys Therapy Indianapolis IN 46202 USA Univ Delaware Dept Phys Therapy Newark DE 19716 USA Drayer Phys Therapy Inst Hummelstown PA 17036 USA

Background. Abnormal joint coupling is thought to be related to overuse injuries in runners. However, researchers do not yet know what constitutes normal joint coupling during running, which makes abnormal coupling difficult to define. Methods. Lower extremity kinematics were collected from 40 recreational runners during stance. Joint coupling methods were applied and, for each method, means and both within- and between-subject variability were calculated. The 95% confidence interval was used to compare differences across coupling relationships and periods of stance. Findings. Timing between rearfoot eversion, tibial internal rotation, and knee flexion were relatively synchronous while relationships involving knee internal rotation were more asynchronous. The excursion ratios showed that every 2 degrees of rearfoot eversion was coupled with I I of both tibial internal rotation and knee internal rotation. vector coding results showed that just beyond maximum loading, all joint coupling relationships resulted in relatively equal amounts of motion, while the within-subject variability was similar throughout stance. The continuous relative phase results showed that the most out-of-phase coupling occurred in the periods around heel-strike and toe-off while the most in-phase coupling occurred in the period just beyond maximum loading of the leg. The continuous relative phase within-subject variability was greatest at the periods around heel-strike and toe-off and smallest just beyond maximum loading. Interpretation. With a better understanding of joint coupling in uninjured runners, these data will help to serve as a reference for future studies investigating the relationship between running injuries and abnormal joint coupling. (C) 2007 Elsevier Ltd. All rights reserved.

关键词： continuous relative phase excursion ratio running timing difference variability vector coding

来源：评论

学校读者我要写书评

暂无评论

Isolated Hamstrings Fatigue Alters Hip and Knee Joint Coordination During a Cutting Maneuver

引用

JOURNAL OF APPLIED BIOMECHANICS 2015年第2期31卷 102-110页

作者： Samaan, Michael A. Hoch, Matthew C. Ringleb, Stacie I. Bawab, Sebastian Weinhandl, Joshua T. Old Dominion Univ Dept Mech & Aerosp Engn Norfolk VA USA Old Dominion Univ Sch Phys Therapy & Athlet Training Norfolk VA USA Old Dominion Univ Dept Human Movement Sci Norfolk VA 23529 USA

The aim of this study was to determine the effects of hamstrings fatigue on lower extremity joint coordination variability during a sidestep cutting maneuver. Twenty female recreational athletes performed five successful trials of a sidestep cutting task pre- and postfatigue. Each participant completed an isolated hamstrings fatigue protocol consisting of isokinetic maximum effort knee flexion and passive extension contractions. vector coding was used to examine hip and knee joint couplings (consisting of various planar motions) during the impact and weight acceptance phases of the sidestep cut stance phase. Paired t tests were used to analyze differences of each phase as an effect of fatigue, where alpha was set a priori at .05. The hip rotation/knee rotation coupling exhibited a significant decrease in coordination variability as a function of fatigue in both the impact (P = .015) and weight acceptance phases (P = .043). Similarly, the hip adduction-abduction/knee rotation coupling exhibited a significant decrease in coordination variability in the weight acceptance phase (P = .038). Hamstrings fatigue significantly decreased coordination variability within specific lower extremity joint couplings that included knee rotation. Future studies should be conducted to determine if this decrease in coordination variability is related to lower extremity injury mechanisms.

关键词： variability vector coding knee kinematics

来源：评论

学校读者我要写书评

暂无评论

Effects of strength training on the biomechanics and coordination of short-term maximal cycling

引用

JOURNAL OF SPORTS SCIENCES 2022年第12期40卷 1315-1324页

作者： Burnie, Louise Barratt, Paul Davids, Keith Worsfold, Paul Wheat, Jonathan Stephen Northumbria Univ Dept Sport Exercise & Rehabil Newcastle Upon Tyne Tyne & Wear England Sheffield Hallam Univ Sport & Phys Act Res Ctr Sheffield S Yorkshire England English Inst Sport Biomech Manchester Lancs England CORDA BAE Syst Digital Intelligence Manchester Lancs England Univ Chester Sport & Exercise Sci Chester Cheshire England Sheffield Hallam Univ Coll Hlth Wellbeing & Life Sci Room F603Robert Winston BldgBroomhall Rd Sheffield S10 2DN S Yorkshire England

The aim was to investigate the effects of a gym-based strength training intervention on biomechanics and intermuscular coordination patterns during short-term maximal cycling. Twelve track sprint cyclists performed 3 x 4 s seated sprints at 135 rpm, interspersed with 2 x 4 s seated sprints at 60 rpm on an isokinetic ergometer, repeating the session 11.6 +/- 1.4 weeks later following a training programme that included two gym-based strength training sessions per week. Joint moments were calculated via inverse dynamics, using pedal forces and limb kinematics. EMG activity was measured for 9 lower limb muscles. Track cyclists 'leg strength" increased (7.6 +/- 11.9 kg, P = 0.050 and ES = 0.26) following the strength training intervention. This was accompanied by a significant increase in crank power over a complete revolution for sprints at 135 rpm (26.5 +/- 36.2 W, P = 0.028 and ES = 0.29). The increase in leg strength and average crank power was associated with a change in biceps femoris muscle activity, indicating that the riders successfully adapted their intermuscular coordination patterns to accommodate the changes in personal constraints to increase crank power.

关键词： EMG joint powers maximal power resistance training sprint cycling vector coding

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：