ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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THE CONTRIBUTION OF ELBOW EXTENSION TO WRIST SPEED IN CRICKET FAST BOWLERS
Get PDFThe purpose of this modelling study was to assess the sensitivity of wrist joint speed to systematic manipulations of empirical elbow joint flexion-extension kinematic profiles. The joint kinematic profiles of 12 cricket fast bowlers were entered into a Forward Kinematic Model and the elbow joint kinematic profiles were subsequently amplified to elicit wrist speed changes. An amplification factor of zero decreased wrist speed by a mean of 8.6% (± 6.9%), whereas an amplification factor of two increased speed by a mean of 8.8% (± 7.1%). An opposite relationship was found for two participants who extended the elbow joint prior to release and it is proposed that an internally rotated humerus will displace the wrist joint posteriorly when the elbow joint is extending
READ AND REACT: EFFECTS OF TASK COMPLEXITY ON MOTOR SKILL EXECUTION
Get PDFPerformance in team sports requires players to both observe their game environment and proceed with technical skill. This case study evaluated if changing the complexity of a perceptual-motor task caused technical performance changes. Kinematic data were collected and analysed for 34 handballs across four levels of complexity using visual and auditory stimuli (simple-response, choice response, choice response with distractor, choice response with cross modality distractor). Kinematic differences were found between the simple response and choice response task for six out of 10 parameters. Although differences occurred, the effect of distractor stimuli on handball kinematics was unclear. The cognitive complexity of a task may affect technical performance and therefore has implications for biomechanical testing environments
SUCCESSFUL FACTORS OF 540° DWIHURYEOCHAGI IN TAEKWONDO
Get PDFThe purpose of our study was to provide fundamental information about success factors of 540° Dwihuryeochagi in Taekwondo. Twenty Taekwondo athletes who participated in the 2012 Taekwondo Kyukpa Wang (breaking king) championship: ten successful athletes (S, age: 23.1±1.6 yrs, height: 171.0±3.5 cm, body mass: 66.4±7.1 kg) and ten failed athletes (F, age: 22.3±1.8 yrs, height: 172.1±5.4 cm, body mass: 64.4±4.2 kg) were selected. Three-dimensional motion analysis using a system of 3 video cameras with a sampling of 60 fields/s was performed during the competition of 540 ° Dwihuryeochagi. Based on the findings, it is concluded that success factors of 540° Dwihuryeochagi were horizontal velocity of COM during P1, vertical velocity of COM during P2, and the time, kick distance, velocity and angle of lower extremities of P3-P4
SHORT-TERM EFFECTS OF 3 DAYS INTENSIVE WHOLE BODY VIBRATION EXPOSURE ON MUSCULAR ACTIVATION STRATEGIES
Get PDFThe aim of this study was to investigate 3-days intensive whole body vibration (WBV) exposure on activation strategies of lower extremity muscles. For this purpose, six male athletes’ dominant leg muscles (Tibialis Anterior(TA), Gastrocnemious Medialis(GM), Vastus Medialis(VM), Rectus Femoris(RF), Vastus Lateralis(VL) and Biceps Femoris(BF)) were recruited voluntarily. Before the trails their baseline electromyography (EMG) values were taken for reference evaluation. After that, they were trained static semi-squat position with 120o knee flexion angle on vibration platform (vertical vibration; 4 mm(high), 30 Hz), during 3 days. The subjects were exposed to vibration 6 times for duration of 60 seconds with a 2 minutes rest between each treatment. Consequently, 3 days intensive WBV exposure caused a progressive increase in EMG activity (
ASSESSMENT OF LOWER LIMB ASYMMETRY: DIFFERENCES DURING ISOMETRIC AND STRETCH-SHORTENING CYCLE TASKS
Get PDFAssessment of limb function asymmetry is of interest to practitioners due to its role in return to play guidelines and reported links to injury. Dynamometry is one of the most commonly used methods of assessing muscle function, but the mode of contraction used is different to the stretch-shortening cycles experienced during real-life activities. The aim of this study was to compare measures of limb function asymmetry during isometric and stretch-shortening cycle tasks and investigate agreement between the methods. Different between-limb effect sizes were observed between limbs dependent on test used, with different ranges of asymmetry observed. Agreement between methods was very poor. These results show the importance of assessing asymmetry in a condition that is as similar as possible to the task of interest
EFFECTS OF EXERCISE ON ANKLE PROPRIOCEPTION DURING SIXTEEN WEEKS OF TRAINING AND EIGHT WEEKS OF DETRAINING IN OLDER ADULTS
Get PDFThis study evaluates the ankle proprioception in older adults. Sixty women (age 62.1±4.3yr) were randomly assigned to three groups to undergo a 16-week training (one group practice Tai Chi,one group practice brisk walking and one group reading) and 8-week detraining program. Proprioception of ankle plantarflexion (PF), dorsiflexion (DF) were measured, better proprioception is defined as being able to detect a smaller degree in joint angle. The results showed that degree PF and DF changes earlier and were smaller in TG than in BG in training; degree of PF and DF declined in all groups during the detraining, but TG exhibited a significant difference with pre-training data. So Tai Chi can more effectively improve and maintain ankle proprioception as well as prevent fall in old age. However, the extent of benefit depends on the regularity of training in older adults
THE ROLE OF WALKING AND RUNNING VELOCITY ON OSTEOGENIC POTENTIAL
Get PDFThis study assessed the ground reaction forces (GRF) associated with walking and running at a variety of speeds and compared these kinetic values to the landing after a maximum counter-movement jump in order to understand the osteogenic potential for these activities. Twenty-four women walked and ran over a force platform at slow, medium, and fast walking and running speeds, which were assessed using Doppler radar. Landing vertical peak GRF and rate of force development (RFD) were analyzed for all movements using a force platform. In almost all cases, higher walking or running speeds resulted in statistically significant increases in GRF and RFD. Based on the findings of this study, moderate to fast sprints should be prescribed in the training programs for those who seek to maximize their bone health
CHANGES IN LOWER-LIMB MUSCLE FORCES WITH PROPHYLACTIC KNEE BRACING DURING LANDING AND STOP-JUMP TASKS
Get PDFProphylactic knee braces are designed to prevent knee injuries, which often occur during sports such as basketball and volleyball, but their efficacy is debated. The purpose of this study is to calculate and compare lower-limb muscle forces in braced and unbraced recreational athletes during landing and stop-jump tasks. Experimental motion capture and ground reaction force data were collected from five participants with and without a knee brace. Subject-specific musculoskeletal models were created in OpenSim and were used to calculate muscle forces. Preliminary results indicated that knee bracing altered both the magnitude and timing of muscle actions. This study provides insight into the likely role of prophylactic knee bracing and muscle function in knee protection
EFFECTS OF A 8 WEEK-CORE STABILITY TRAINING ON JUNIOR MALE SOCCER PLAYERS´ STATIC BALANCE PERFORMANCE
Get PDFThe purpose of study was to investigate effectiveness of the Core Stability exercises on junior level soccer players static balance performance. 27 soccer players participated in this study. Pre-test post-test control group design was used. Mixed Design ANOVA was conducted to understand effectiveness of exercise program on static balance performance. There were no any significant main effect of visual system and time in Anterio-Posterior and Medio-Lateral directions for bilateral stance. Moreover, no significant group effect was observed for bilateral and unilateral static balance performance. Main effects of visual system and time in Anterio-Posterior direction during unilateral stance were observed. Interaction between visual system and test were observed in Medio Lateral direction
A NOVEL APPROACH TO MONITOR THE GROUND REACTION FORCE
Get PDFCustom developed spikes have been used to monitor the vertical GRF temporally resolved for body weight, walking, and jumping on a synthetic surface. All the data is derived from the time dependent voltage variations of piezo spikes, which are observed with the aid of a computer controlled transient recorder. The detection is obtained on two piezoelectric spikes of identical size and shape placed under heel and forefoot. Monitoring is performed on ten healthy athletes with age 19 ± 4 years, mass of (57 ± 6) kg, and a BMI of 21 ± 3. The force resolution is ± 0.25 N and the temporal resolution is 0.01 ms. The contact time, take off time, impact force, active force phases of heel and forefoot have been quantified. The system is of compact size and battery driven, and allows for monitoring of on-field GRF sporting activities