ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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THE RELATIONSHIP OF THE REACTIVE STRENGTH INDEX-MODIFIED AND MEASURES OF FORCE DEVELOPMENT IN THE ISOMETRIC MID-THIGH PULL
Get PDFReactive strength index-modified (RSImod) may be an important variable to measure in the performance testing and monitoring of athletes, and very little work has examined this particular variable. One hundred six Division-I collegiate athletes performed countermovement jumps and the isometric mid-thigh pull. The relationship between the RSImod and variables from the isometric mid-thigh pull representative of explosive performance were evaluated with Pearson’s r. Relationships between RSImod and variables related to explosiveness ranged from moderate to large. Maximum and relative maximum strength had the strongest correlations to RSImod. RSImod appears to be a measure of explosiveness. Furthermore, an athlete’s isometric strength may be an indicator of their reactive strength
THE KINEMATICS CHAIN OF INSTEP KICKING OF SOCCER WITH UPPERBODY CONSTRAINED: A PILOT STUDY
Get PDFThe purpose of this study was to understand the kicking performance when the upperbody motion has been limited. One player in the college cup level A volunteered to participate in this study (Aged: 20 years, Height: 172 cm, Body mass: 65 kg). A VICON motion capture system (200 Hz) was used to capture the kicking motion. The participant was asked to kick the ball both using an arm swing and not using an arm swing. The Visual3D was used to calculate the segment velocity, angular velocity, and kinetic chain. The results indicated that kicking with arm swing had a greater ball and lower-extrimity segment velocity. The main effect for lower ball velocity during kicking without arm swing is the decreased angular velocity at the ankle joint. When arm motion has been limited, players should noticed that the ankle joint needs to follow through after foot-ball contact
GROUND REACTON FORCE OF TABLE TENNIS PLAYERS WHEN USING FOREHAND ATTACK AND LOOP DRIVE TECHNIQUE
Get PDFThe subjects were 10 excellent ping-pong players in China. The table tennis techniques of the forehand attack and forehand loop drive were tested, using the measurement methods of the KISTLER force-plate system. The results showed that the biggest GRF of the attack technique in vertical direction was higher than the loop drive technique, and the biggest GRF of the attack technique in left-right direction and the fore-aft direction were mostly lower than the loop drive technique
ELBOW JOINT VARIABILITY DURING THE ROUND OFF IN FEMALE GYMNASTICS
Get PDFBased on a within-gymnast analyses this study aimed to examine the variability in elbow joint kinematics and kinetics of expert gymnasts in the execution of the round-off with different hand position. Six international level female gymnasts performed 10 trials of the round-off from a hurdle step to back handspring with “parallel” and “T-shape” hand position. Two force plates were used to determine ground reaction forces. Eight infrared cameras were employed to collect the kinematic data. Gymnast-specific variability was calculated using coefficient of variation (CV%) in each discrete kinematic and kinetic measures. In conclusion higher variability in the elbow joint abduction angle and adduction moment of force in the T-shaped hand position may leads to reducing repetitive abduction stress and thus protect elbow joint from overload
DYNAMICS OF SUPPORT HIP JOINT DURING MAXIMAL VELOCITY SPRINTING
Get PDFThe purpose of this study was to investigate the relationship between lower trunk motion and the support leg hip joint torque by three-dimensional (3D) analysis. Eight male sprinters ran 60-m with maximal effort from a standing position. Kinematic and kinetic data at the maximal speed phase were obtained with a 3D motion analysis system (250Hz) and force platform (1000Hz). As a result, there was a marginally significant negative correlation (r = -0.70, p = 0.051) between a running velocity and the peak backward angular acceleration of the support-side lower trunk during terminal support phase. It seems to be necessary for diminishing the backward angular acceleration to exert a large support hip adductor torque during the terminal support phase. These findings might be useful to improve maximal running velocity
Angle of attack of center of mass during the running of an entire 100m dash
Get PDFThe angle of attack is related to the body posture and changes during sprinting because of changes in the horizontal velocity. The aim of this study was to analyze the angle of attack of the center of mass and the horizontal velocity during a 100 m dash. Twelve video cameras were positioned along a running track to obtain the position of the center of mass. The horizontal velocity was derived from the position data. When the different sides were compared, the angles were lower on the right side than on the left side (P < 0.05), which tended to decrease with increasing horizontal velocity. The results show the variability of the angle of attack as associated to the horizontal velocity, and the differences considering laterality
INFLUENCE OF JUMPING MEASURES AND SQUAT 1RM ON SPRINT SPEED IN RUGBY UNION PLAYERS
Get PDFThis study examined the relationship of countermovement (CMJ), squat (SJ), and rebound jumps (RBJ), estimated 1RM back squat (SQ), contact time (CT) and Reactive Strength Index (RSI) for the RBJ to 30 m sprint time of sub-elite, semi-professional Rugby Union players. The results show that with the exception of SQ and CT, all variables were significantly (p .575). The best determinant of predicting 30 m sprint time was RSI. The relationships of SJ, CMJ, and RBJ jump height and RSI to 30 m sprint time suggest that these rapid movements are all common in Rugby Union players. The results show that estimated 1 RM back squat has little influence on sprint performance
INTRASUBJECT VARIABILITY OF THE KINEMATICS OF THE VERTICAL JUMP
Get PDFThe variability of the kinematics of the vertical jump was studied in a sample of eight young adults. Six maximal effort vertical jumps from each subject were analyzed with the Peak Motus 2D videography (60 Hz) system. Kinematics of a seven segment model were calculated from the initiation of downward movement to five frames after take-oft. The intrasubject variability was usually small but depended on the kinematic variable of interest. Discrete angular kinematic variables of key events had mean
standard deviations between 2.7 and 6.5 degrees. Most displacement and velocity variables had coefficients of variation between 1 and 1 0 percent. These vertical jumpers used consistent movement patterns so single jumps would be representative of normative performance
A CONSIDERATION OF QUANTITATIVE EVALUATION OF DEXTERITY IN SPORTS EXERCISE
Get PDFThe aim of this study was to quantitatively evaluate dexterity on athletic motions. Subjects were three skilled and three non-skilled weight lifters. They performed power clean that is a strength-training motion. We measured trajectories of joints by using motion capture system, and calculated joint torque according to dynamical equations using only kinematic data. In order to evaluate the strength of stretch reflex and that of proprioceptive feedbacks, we employed curve fitting with the recursive least squares method in our proposed torque model that includes a term caused by stretch reflex and feedback terms with respect to the COP and COM position. The results show that the calculated coefficients reflect some dexterous behavior of skilled motions
THE CREATION AND VALIDATION OF A LARGE-SCALE COMPUTER MODEL OF THE GOLF SWING
Get PDFThe aim of this study was to create and validate a full-body musculoskeletal model of a golfer performing a swing with their driver club. An elite female participant performed ten shots with her driver while wearing retro-reflective markers. An optical 3-D 6-camera system captured the kinematics of the markers at 400 Hz on the participant for each trial. A launch monitor device recorded the ball and club head conditions at impact. The kinematic data from one representative trial was selected to drive inverse and forward dynamics simulations of the created model. The validation results showed a very high level of agreement between experimental and simulated trajectories for selected markers (mean r = 0.966