• Volume 23,Issue 3,2008 Table of Contents
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    • Graphic musculoskeletal model for biomechanical analyses and animation in sport sciences and medicine

      2008, 23(3):177-192. DOI: 10.3871/j.1004-7220.2008.3.192.

      Abstract (3090) HTML (0) PDF 0.00 Byte (1) Comment (0) Favorites

      Abstract:The ability to combine physiology and engineering analyses with computer graphics has opened the door to the possibility of creating the "Virtual Human" reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants, fracture fixation devices, rehab and exercise equipment and a robust computational platform for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated in the utility software system and the database, the VIMS (Virtual Interactive Musculoskeletal System). In the database, long bone geometry, dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is available for the end-users to perform biomechanical analyses interactively. Examples using the graphic models and the computational algorithms in a virtual laboratory environment for: 1) biomechanical analysis of skeletal kinematics; 2) shoulder joint force and contact pressure distribution in overhead activities; 3) hip joint contact pressure distribution in activities of daily living; 4) ankle joint contact stress and ligament loading during gait; 5) ankle injury and therapeutic management simulation; 6) knee continued passive motion and computer-aided rehabilitation; are used to demonstrate the utility of the unique database and the biomechanical simulation technology. This integrated system will impact on sport sciences and medicine through basic research, athlete screening/training, injury prevention and rehabilitation to benefit both the elite and recreational athletes.

    • Intersegmental dynamics analysis of the lower limb in sprint run-ning

      2008, 23(3):193-201. DOI: 10.3871/j.1004-7220.2008.3.201.

      Abstract (2551) HTML (0) PDF 0.00 Byte (1) Comment (0) Favorites

      Abstract:Based on the kinematic and dynamic measurement and the intersegmental dynamics, the present study investigates the function of active muscle torque and different passive torques on lower limb joints during maximal sprint running in order to get insights into the effect of movement control on sport performance and injury prevention. Methods The subjects were 8 national level sprinters (best performance: 10.27 s–10.80 s). High-speed infra-red motion analysis system with 8 cameras (300 Hz) and force-plate system (1200Hz) were used to record kinematic and ground reaction force data synchronously. Based on inverse dynamics and intersegmental dynamics model, various interaction torques of lower limb during sprinting maximal speed phase were quantified. Results The results revealed that the dominating passive torque during the ground contact phase was the ground reaction torque (GRT), which acted to extend the knee joint during the initial stage of ground contact. The muscle produced a flexion torque in order to counter-balance the effect of GRT. This may lead to potential injury of hamstring muscles. In contrast, the inertial torque (the motion-dependent torque) dominated during the swing phase of sprinting, which reached its maximum during the later swing phase. Conclusion Both the initial stage of ground contact phase and the later swing phase of sprinting were considered as major phases in which hamstring muscle strain injury may occur. The muscle strain injury is a main limiting factor for enhancing sport performance.

    • Analysis of female drop jerk in sport biomechanics

      2008, 23(3):202-207. DOI: 10.3871/j.1004-7220.2008.3.207.

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      Abstract:Objective This article is to study the drop jerk in the characteristics of kinematics and dynamics, and offer the theoretical basis to athletes and coaches to think and look for the clean & jerk mode that suits themselves. Methods The study selects the testing method that three-dimensional video synchronizes camera with force platform. Results The results indicate the height of drop under the barbell to drop jerk is lower, the velocity of drop jerk under the barbell of gravity center of body is higher, the rising distance of barbell is short, the rising velocity which barbell needs is less; its stabilization angle and balance angle of drop jerk are much less, its stability is very bad and it is easy to lead being lost, the duration of the drop under the barbell and uprising of the drop jerk is longer. The distance of uprising is also longer, so the body will consume more energy. Conclusion The jerk force of drop jerk is smaller than the others, but its stability is very bad in drop under the barbell and uprise phases.

    • Research on passive cushiony characteristics of body in land-ing impact with system identification methods

      2008, 23(3):208-215. DOI: 10.3871/j.1004-7220.2008.3.215.

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      Abstract:Objective This method is explored in solving the mechanical component parameters of models referring to body landing impact with system identification,and the validity and practicability of relative method is validated combined with simulation analysis. Methods the body is simplified to a muster parameter physical system of one degree freedom with a wobbling mass and a rigid mass, and then a mathematical model with state space method is lead out, thus the generalized equation is obtained in virtue of n4sid sub-space system identification methods,and more the estimated values of mechanical component parameters of relative model is find out by the use of constrained optimization method. Results the wobbling mass augments accompanied with the increased landing height;there are likely ranges for the estimated values of elastic and viscos component parameters;there are better fitting degrees between output produced by simulation computations and practical output of the body system. Conclusions it is a effective method to give the estimated values of mechanical component parameters reflected the body cushiony characters in the two-mass and one degree freedom system model with the system identification methods.

    • Dynamic research on diving athlete's person-board coupling when the off beat takes off

      2008, 23(3):216-222. DOI: 10.3871/j.1004-7220.2008.3.222.

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      Abstract:Objective To study diving athlete's pedaling force with its function changes when getting person-board coupling with both feet gathering to press the springboard. Methods To obtain the kinematics parameters by using theoretical analysis method with material mechanics' bending stress, vibrating dynamics research technique. Results1. Deflection equation of springboard's line is δ0=y板(1)=P/6E1[-ι3+3ι3+(a2-4ιa)ι+ιa2]=ι(ι-a)2/3E1P 2. The impact stressreceived by springboard is Pd=K(P/K+(P2/K2+2ph/K)1/2) 3. The person-board coupling's natural timing frequency is ω合=(k/(m+■))1/2=((3El/(m+■)ι(l-a)2)1/2)4. Under the similar outside force, with the pivot approaching the springboard fixedend, the vertical displacement of the front end increases; with the pivot moving ahead(approach board point), the board rigidity increases correspondingly. 5. The nearer the pivot to the springboard fixed end, the bigger the board frequency will be, With the pivot moves to the board point, the board frequency reduces, while the board rigidity increases correspondingly. And if the pivot position remains unchanged, the nearer the springboard position approaches front end, the bigger the vertical displacement of the front end will be. 6. The off beat plywood's frequency should be higher if the athlete's weight is lighter; once upon start to final jump, the frequency with different weights tends similar. 7. The board point position spatial board frequency is 3.750 (Hz), and the board damping ratio is 1.5%-2.0%, obtained from the measurement by the acceleration sensor. Conclusions 1. In the true sense, person-board coupling should be the person's quality and the board quality becomes a whole one to move, and at this time the frequency is the person-board coupling frequency. During this time, the human center of gravity and the speed with the foot touching movement should be consistent in the vertical direction. 2. It is not the same for the different athlete's board impulse and the board's biggest reaction. With body weight increase, the athlete's impulse falling on the board will be bigger,and in turn the board reaction would correspondingly increase. 3. By observing the angular speed changes from the board buffering pedal extending, the hip, knee and malleolus joints simultaneously participated in the buffering, with the time order as the hip, the knee and the malleolus, which indicate that when human body needs to overcome the big resistance from pedal extends, the big joint first has the activity to deal with the resistance so that it causes the link to have the angle accelerated motion.

    • Studies of interference forces of waves on flatbottmed yacht

      2008, 23(3):223-225. DOI: 10.3871/j.1004-7220.2008.3.225.

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      Abstract:Objective To study the interference forces of waves on flat-bottomed yacht. Methods The interference forces from first-order regular waves on flat-bottomed yacht were simulated and calculated based on linear slice theory and to analyze its influence on the yacht's movement. Results The effects of oblique waves on interference forces and the yacht's sidelong floating, the influence of the encounter angle (angle between the direction of wave and course) on the interference forces and its cycle, and the effect of wave frequency on the cycle of interference forces were all analyzed. Conclusion The encounter angle was a key factor of effects on the movement of flat-bottomed yacht. To keep right course, it should be necessary to adjust the encounter angle timely.

    • Study on monitoring techniques of oar force acted by rowing athletes

      2008, 23(3):226-228. DOI: 10.3871/j.1004-7220.2008.3.228.

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      Abstract:Objective To develop a sensor for measuring oar force in rowing real time. Methods A horseshoe sensor was developed to be easy to fix to the thole of gig. The mount of sensor does not change any structure of the gig. The rowing of athletes will not be obstructed by force measurement. Results The linear load-strain relation was measured in the laboratory experiment. Such linear relationship ensures that the electrical output of the sensor is proportion to the oar force exerted by athletes.

    • Software developed for estimate mechanical functions of the lower extremities muscles

      2008, 23(3):229-233. DOI: 10.3871/j.1004-7220.2008.3.233.

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      Abstract:Objective To develop an applied software to describe and estimate the mechanical functions of the lower extremities muscles during movement. Methods The original data of 3D coordinates of muscle attachments of lower extremities and the methods to establish the muscular function model comes from a previous research[3]. Results The software developed in this study could output the values of function parameters of lower extremities muscles for any simulated joint angle configuration or real motions. Conclusion The data from the computer model could coach specific muscles strength training to improve athletic performance and also have a good prospect of application in the related fields of medicine.

    • Measurement of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome

      2008, 23(3):234-236. DOI: 10.3871/j.1004-7220.2008.3.236.

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      Abstract:Objective To investigate the feasibility of measurement of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome. Methods The endoscopic release procedures were performed in 47 wrists with carpal tunnel syndrome in 38 patients. The pressure in the carpal canal was measured in 21 wrists of 16 patients preoperatively and postoperatively in the resting position, the extension position, the flexion position and the Okutsu test position. Results Compared with the pressure in the carpal canal before the operation, the pressure after the operation decreased significantly (P<0.01) in the same position. Conclusion The pressure change before and after the operation could be used to assess the extent of release and avoid the incomplete decompression procedure.

    • Progress in biomechanics of sports injury

      2008, 23(3):237-239. DOI: 10.3871/j.1004-7220.2008.3.239.

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      Abstract:Biomechanics of sports injury is an interdisciplinary that has been rapid developed recently years. Its development have been featured as: 1) the research has extended from bone to soft tissue; 2) various kinds of new techniques are developed and applied; 3) the research has been developing in either micro or macro field; 4) the research has been extented from vitro to vivo; 5) sports injury and biomechanics facilitate each other. In this article, authors would have a review on the progress in this field.

    • Review on the research of the mechanisms of non-contact ACL injuries

      2008, 23(3):240-247. DOI: 10.3871/j.1004-7220.2008.3.247.

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      Abstract:Anterior cruciate ligament (ACL) tearing is one of the most commonly knee injuries in sports. Most ACL injuries in sports occur because of non-contact mechanisms. A better understanding of non-contact ACL injury characteristics as well as ACL loading and injury mechanisms is critical both for prevention and treatment of non-contact ACL injuries. This review summarized the researches on non-contact ACL injury characteristics, ACL loading and its injury mechanisms. The literatures demonstrated that sagittal plane biomechanical factors showed main affect on ACL loading, such as small knee flexion angle, great posterior ground reaction force, and great quadriceps muscle force. A great posterior ground reaction force is associated with a great quadriceps muscle force, which would cause a great anterior draw force at the proximal end of the tibia. A small knee flexion is associated with a large patella tendon-tibia shaft angle and ACL elevation angle, which would result in great ACL loading Current literature also demonstrates that ACL is not the major structure of bearing knee valgus-varus moment and internal rotation moment loadings. Knee valgus-varus moment and internal rotation moments alone are not likely to be the cause of ACL injuries without medial or lateral colletorial ligament injury as the most of non-contact ACL injuries clinically observed.

    • Yacht sports and the forces on the yacht

      2008, 23(3):248-251. DOI: 10.3871/j.1004-7220.2008.3.251.

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      Abstract:In allusion to 2008 Olympic Games, the process changing from thrust force to lift force by wind on the sail in the development of yacht sailing race was reviewed by analyzing the forces pushing on yacht. The history of yacht sailing games was also given the retrospect and discussed the investigative methods used.

    • Real-time monitoring system for multiple parameters on aquatics sports

      2008, 23(3):252-256. DOI: 10.3871/j.1004-7220.2008.3.256.

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      Abstract:Real-time monitoring system for multiple parameters on Aquatics Sports, utilizes Wireless Sensor Network (WSN)technology, to monitor and analyze the multiple parameters (including the vessel velocity, tholepin pressure, heart rate, etc.) on Aquatics Sports. This system includes sensors for the signal collecting and processing, the ZigBee wireless transmission module, the visual interface for data analysis and processing on the MUPC terminal. This system can deliver the heart rate, tholepin pressure and other parameters from a training sportsman to the coach's UMPC in real time. It helps the coach to rearrange and adjust the training schedule immediately, which can greatly improve the training efficiency in order to ensure the high competence.

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