ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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SIMULATION SYSTEM FOR IMPROVING TENNIS STROKE MOTION
Get PDFThe purpose of this study was to construct a system that can simulate tennis stroke motion for competition level enhancement of players. To do so, 10 female tennis club players (1 9- 23 years old) of University of Tsukuba were selected for a biomechanics study using three-dimensional stroke motion analysis method, in a total of 10 trials. Using obtained results on joint angles of the whole body, the best results of university tournament and racket head speed at impact, a database was constructed. Principal component analysis was used to classify the motion patterns into the principal component scores. Based on the principal component score and optimization theory, we generated a simulation system to predict competition level and racket head speed, and thus a new stroke motion, which can be expressed using 30 animations
EFFECTS OF GRAVITY ON MULTI-DIGIT TORQUE PRODUCTION TASK IN HUMANS
No full textIn this study we investigated the effect of gravity on multi-digit prehension to know how the digits\u27 force and moment are organized in the imposed static constraints according to the gravity. Specfically, we tested if decoupling of grasping and rotational equilibrium control is even valid during grasping in the microgravity condition. There were two experimental conditions: gravity-induced (GI), and microgravity conditions (MG). For the MG condition, the handle was attached to the end of the robot-arm, which produced a count-balanced force for the weight of the handle and hand. The results showed that the selected experimental variables were separated into two sub-sets in both GI and MG conditions. Thus, we can conclude that the grasping stability is independent from the rotational equilibrium control regardless of the gravity acting on the hand-held object
A COMPARISON OF DIFFERENT METHODS FOR IDENTIFYING TRANSITION STEPS IN THE ACCELERATION PHASE OF SPRINT RUNNING
Get PDFTransition steps have previously been identified in the acceleration phase of sprinting. To compare transition steps detected using different measures, three sprinters performed maximal 50 m accelerations from blocks. Sagittal plane kinematics were collected using five 50 Hz cameras while touch-down and toe-off events were identified using a 200 Hz panning camera. Centre of mass height, shin angle and trunk angle at touch-down as well as the step where flight time exceeds contact time were used to detect transitions. Comparable transitions were identified based either on centre of mass height or shin and trunk angles at touch-down. These results provide further knowledge to the way in which the acceleration phase is structured and allows athlete specific biomechanical analysis to aid in the coaching of different sections of the acceleration phase in sprinting
BIOMECHANICAL ANALYSIS A SEQENCE OF ANGULAR VELOCITY AND COORDINATED MUSCLES ACTIVITY DURING BASEBALL HITTING
Get PDFThe purpose of this study was to analyse a sequence of rotations and coordinated muscles activities of upper body. Using kinematic and EMG data from 3 recreational university baseball players participating in this study, we computed the angular velocity of trunk, pelvis, bat and trunk-pelvis rotation angle and PMT of upper body muscles. Trunkpelvis rotation angle was 22 ° before the bat-ball contact. The pelvis, trunk, and bat showed a sequence of angular velocity beginning with the hip, followed by the trunk, and end tip of the bat. Additionally, PMT of upper body muscles generated right pectoralis major(1.03 sec.), right external oblique(1.11 sec.), left thoracloumbar fasci(1.12 sec.), left external oblique(1.13 sec.), right latissimus dorsi(1.15 sec.), left latissimus dorsi(1.16 sec.), right thoracloumbar fascia(1.16 sec.), left pectoralis major(1.25 sec.), on at a time during baseball hitting motion. PMT of upper body muscles were related to the shifting and rotating of body segment and this action can be considered the coordinated muscle activities of upper body
THE EFFECTS OF WHOLE-BODY VIBRATION ON EMG OF LEG MUSCLES WHICH ARE DIFFERENT FATIGUE RESISTANT DURING STATIC CONTRACTIONS
Get PDFThe purpose of the present study is to determine the effects of static whole body vibration (WBV) stimuli at low (2 mm) and high (4 mm) amplitudes and various frequencies (30-35- 40 Hz) on the neuromuscular responses of leg muscles which are different fatigue resistant. The fatigue protocol used for the determination of the fatigue index (FI).The study population was divided into two groups according to the values obtained by the FI (Group I: Less Fatigue Resistant (LFR), n=11; Group II: More Fatigue Resistance (MRF), n=11). Study results showed that LFR group that experienced a significantly higher percentage increase in the EMG activation values during higher frequencies (40 Hz) and amplitudes (4mm) (
EFFECT OF POST-ACTIVATION POTENTIATION ON KINEMATICS AND KICKING PERFORMANCE IN A ROUNDHOUSE KICK WITH TRAINED MARTIAL ARTS PRACTITIONERS
Get PDFThe purpose of this study was to examine if kicking with elastic resistance (ER) during warming up could initiate Post-Activation Potentiation (PAP), and increase kinematics and performance on subsequent explosive kicking. Five woman and eleven men (n=16) with a background in kickboxing and/or TaeKwonDo performed two warming up strategies with subsequent testing. Kicking performance, defined as kicking velocity with the foot was measured 3D. In addition, muscle activity of the prime movers was measured. Kicking velocity of the foot increased by 3.3% after performing a warming-up strategy including kicking with ER (p=0.009). Increases were also recorded in muscle activity in m. vastus medialis (35.2%, p=0.05), rectus femoris (43.9%, p=0.04). The study show a positive effect on kicking performance after performing a warmup strategy including kicking with ER
DOES SIDE OF AMPUTATION AFFECT 200- AND 400-M RACE TIME IN SPRINTERS USING RUNNING-SPECIFIC PROSTHESES?
Get PDFCurrent Paralympic guidelines for track events are generally based on level of amputation, not side of amputation. Since 200- and 400-m sprint races are performed in a counter clockwise direction, the effects of amputations side on sprint race performance in athletes with unilateral lower limb amputation should be investigated. Forty-five unilateral transtibial amputees participating in elite-level 200- and 400-m races were analysed from publicly available Internet broadcasts. For each athlete, official race time, and amputation side were determined. We found no significant difference in official race time between left and right side amputees during the 200- and 400-m sprint, indicating that sprint performance on a standard track in amputee athletes is not affected by amputation side
EFFECTS OF SEAT POSITION ON JOINT LOADS OF THE UPPER EXTREMITIES DURING HANDCYCLING IN WHEELCHAIR-DEPENDENT INDIVIDUALS
Get PDFThe current study aimed to quantify the joint moments of the upper extremities with different seat positions during handcycling in wheelchair-dependent individuals. Sixteen subjects performed handcycling while the handgrip reaction forces were measured by a handgrip instrumented with a six-component load cell and body segment kinematic data by a motion capture system. Both data sets were used to calculate joint moments of the upper limbs during a crank cycle. The loads at the shoulder were affected mostly by the vertical seat positions. The higher the seat, the greater loads transmitted by the muscles with relatively greater strength. The current data will be helpful for future handcycle design and fitting for wheelchair-dependent individuals
DOES THE METHOD OF MEASURING CENTRE OF MASS DISPLACEMENT AFFECT VERTICAL STIFFNESS CALCULATION IN SINGLE-LEG HOPPING?
Get PDFThe purpose of this study was to compare vertical stiffness values calculated from two kinetic and two kinematic estimations of the vertical displacement of the centre of mass. Twenty recreationally active male and female participants completed one 15 s single-leg hopping trial at 2.2 Hz with vertical stiffness calculated for the first 10 complete hop cycles. Vertical displacement was estimated using double integration (DI), first principle (FP), sacral marker cluster (SMC) and segmental analysis (SA) methods. Bland-Altman plots demonstrated the SA and DI methods to have a small bias (0.92 kN/m) and tight 95% limits of agreement (-1.16 to 3.08 kN/m). In contrast, the SMC and FP methods underestimated and overestimated vertical stiffness, respectively. These findings suggest the SA and DI methods can be used interchangeably to calculate vertical stiffness
VERTICAL STIFFNESS DURING MAXIMAL SPRINTING IN A TRANSFEMORAL AMPUTEE: A CASE STUDY
Get PDFRunning-specific prostheses emulate the spring-like behaviour of biological limbs during human running, but little is known about the spring-like leg functions in transfemoral amputees. Understanding of running mechanics is expected to benefit the design of prostheses and to prevent injuries. The purpose of this study was to clarify the spring-like behaviour of sprinters with transfemoral amputations using running specific prosthesis. The vertical stiffness was calculated using a spring-mass model. The vertical stiffness in prosthetic limbs tends to be greater than in intact limbs for transfemoral amputees