ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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AGREEMENT BETWEEN ATTRIBUTES ASSOCIATED WITH BILATERAL JUMP ASYMMETRY
Get PDFThe purpose of this study was to examine the relationship between bilateral countermovement jump (bCMJ) asymmetry and asymmetries in lower extremity flexibility, anthropometry, strength and single leg jump performance. Three criteria were identified for each of these attributes. Thresholds were determined to diagnose asymmetry in all criteria based on exceeding the mean ± sd of the absolute difference between limbs. A total of 145 subjects across a variety of sports were tested. The overall agreement in diagnoses compared to bCMJ were 49.7% flexibility, 58.6% anthropometry, 66.9% strength and 70.3% single leg jumps. Individual attributes had associations of between 27.5-32.5% with actual bCMJ asymmetries and this rose to 72.5% when all attributes were combined. 82.9% of subjects possessed at least one lower extremity asymmetry
KNEE AND ANKLE MUSCLES COACTIVATIONS IN BREASTSTROKE SWIMMING KICK AND RECOVERY: EXPLORATORY APPROACH
Get PDFThe specificities of body position in breaststroke induce important lower limbs solicitations for the swimmers to propel themselves efficiently. Coactivations around the knee and ankle might appear during the powerful leg extension (i.e. push) and for leg replacement (i.e. recovery). The purpose of this exploratory study is to determine muscle activations and coactivations during these two phases at three different velocities. The EMG of four muscles was recorded (BF, RF, GAS and TA). The results showed important activations of the four muscles in the push, contrary to the recovery. However, no significant differences were found for the coactivations in the two phases and for the three velocities. These findings denoted the important resistances occasioned by aquatic environment, both in push and recovery phases, necessitating muscle coactivations to stabilise joints
WHAT CAN WE LEARN FROM TOP 10 PERCENT STUDENTS IN BIOEMCHANICS?
Get PDFThe aim of this study was to revisit the previous study and identify the behaviours that help undergraduate students who achieved a final grade above 90th percentile and achieved most normalized gain of biomechanical concepts. A total of 149 students were recruited from introductory biomechanics classes from three public universities. The first version of Biomechanics Concept Inventory was given during the first and last week of the sessions with a 19-item questionnaire. Fifteen high achievement students in final grade and normalized gain were selected for further analysis. Students’ interest in biomechanics was identified as a common factor that related to high final grades and greatest normalized improvement. Students learning biomechanics in small groups and playing an active and important role may enhance learning and final grade
CHANGES IN THE RUNNING MOTION WITH FATIGUE DURING MIDDLE-DISTANCE RUNNING
Get PDFThe purpose of this study was to investigate the changes in the running motion with fatigue during middle-distance running and get the knowledge about how to maintain the running velocity under fatigued condition by comparing the running motion with fatigue to it with no fatigue. The step length at the fatigued was shorter than the non-fatigued, on the other hand the step frequency was larger than the non-fatigue. The peak ankle joint plantar flexion torque and positive torque power of the support leg at the fatigued were smaller than the non-fatigued, as well as the peak and averaged vertical GRFs. The hip joint torque and power of the recovery leg at the fatigued were significantly larger than the non-fatigued. It is appropriate for maintaining the running velocity to move the recovery leg quickly and increase the step frequency under fatigued condition
THE EFFECT OF INCREASING JUMP STEPS ON THE TAKE-OFF LEG IN BOUNDING
Get PDFThe purpose of this study was to clarify the effect of increasing jump steps in bounding in terms of three-dimensional joint kinetics for the take-off leg. Eleven male track and field athletes performed horizontal bounding from the standing posture. Kinematic and kinetic data were recorded using a Vicon T20 system (250 Hz) and force platforms (1,000 Hz). As jump steps increased, the joint kinetics characteristics are as follows: 1) ankle plantar flexion torque and knee extension torque and power increased, but hip extension torque and power did not increase; and 2) hip external torque and power (negative and positive) increased, particularly hip abduction torque and power. Therefore, in bounding initiated from the standing posture, ankle and knee joint kinetics from the sagittal plane and 3dimensional hip joint kinetics increased, particularly on hip adduction-abduction axis
BIOMECHANICS RESEARCH CONCEPT INVENTORY
Get PDFA pilot study of a test of biomechanics research concepts appropriate for advanced undergraduate and master’s courses was conducted. Students in a master’s biomechanics course (n = 14) took a 30 question Biomechanics Research Concept Inventory (BRCI) the first and last day of the course. The BRCI tested six research concepts areas and several prerequisites from introductory biomechanics. The students entered the class with 42% mastery of prerequisite concepts. Post-course scores significantly improved by a modest 50 percent from pre-course values. The BRCI indicated the largest apparent improvements were in the 2D kinematics, 2D kinetics, and in the reviewing and writing research reports concept areas. The BRCI has potential as a supplement to course grading for assessing learning of biomechanics research concepts
OPTIMUM TECHNIQUE FOR MAXIMISING FORWARD SOMERSAULT ROTATION IN TRAMPOLINING
Get PDFThe purpose of this study was to investigate the optimal technique to produce somersault rotation in forwards rotating somersaulting skills. A 7-segment planar, torque-driven simulation model of a trampolinist was developed. The trampoline was represented by horizontal and vertical force-displacement relationships. The model was evaluated using recorded performances of three forward somersaulting skills. Optimised takeoff technique produced an increase of 9% in rotation potential using a more open shoulder angle and a greater initial horizontal velocity
LONGITUDINAL ASSESSMENT OF YOUNG SWIMMERS’ PERFORMANCE AND ITS PREDICTORS
Get PDFThe purpose of this study was to develop a performance predictor model based on biomechanics. Ninety-one swimmers (44 boys and 47 girls) were evaluated. The decimal age, anthropometrics, kinematics and efficiency parameters were collected in ten different moments over three seasons. Hierarchical linear modeling was the procedure selected to estimate the performance predictors. The decimal age (Estimate: -2.05; P < 0.001), arm span (Estimate: -0.59; P < 0.001), stroke length (Estimate: 3.82; P = 0.002) and propelling efficiency (Estimate: -0.17; P = 0.001) entered the final model. The decimal age, arm span, stroke length and propelling efficiency were the main predictors. Longitudinal assessments seems to be the best way to have a deeper knowledge on how performance main determinants act and affect the performance
RELEASE AND RE-GRASP WINDOWS FOR THE KOVACS ON HIGH BAR
Get PDFThe aim of the study was to determine the size of the release and re-grasp windows used in the Kovacs release and re-grasp on high bar and compare these to the potential time available to re-grasp the bar. One elite male gymnast performed 10 successful Kovacs (out of 10 attempts) which were recorded using an automatic motion capture system. The release and re-grasp windows were determined from the range of performances and the potential re-grasp window was calculated from the period of time the mass centre was within grasping distance of the bar. The gymnast was very consistent and used a small re-grasp window (23 - 27 ms). The potential re-grasp window was large with the gymnast being within re-grasp distance of the bar for 100 ms prior to grasping the bar. It is likely that the gymnast selected a consistent point within this window for the re-grasp
CHANGES IN UPPER EXTREMITY MUSCLE ACTIVATION IN THE PRESENCE OF STRESS
Get PDFThis study examined the muscle activity of the flexor digitorum (FD), biceps brachii (BB), triceps brachii (TB), and pectoralis major (PM) during the American football throw with and without conditions of stress. Male subjects (n=5) with either football or baseball experience threw footballs at targets with distances of 12.91 m, 18.29 m, and 28.91 m. Throwing arm muscle activity was assessed via electromyography. Results showed that the flexor digitorum muscle had lower muscle activation for the stress condition at the long distance along with the pectoral muscle at the middle distance