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FORCE-VELOCITY RELATIONSHIP BETWEEN SPRINTING AND JUMPING TESTING PROCEDURES
Get PDFThe aim of this study was to examine the relationship between the mechanical characteristics of the horizontal and vertical Force-velocity (F-v) profile as well as the performance variables of the sprinting and jumping testing procedures. Twenty high-level sprinters performed two maximal sprints and squat jumps against multiple external loads. Our main findings revealed very large correlations for maximal mechanical power output (Pmax) (r=0.72), as well as for performance variables between the sprinting and jumping tasks (r=-0.81) and large correlations for maximal velocity (V0) (r=0.66). The maximal force (F0) and the slope of the F-v relationship (F-v slope) were not significantly correlated between both tasks. These results suggest that both testing procedures should be performed in order to gain a deeper insight into the maximal mechanical properties and function of the lower-body muscles in high-level sprinters
KNEE JOINT KINEMATICS OF SUPPORT LEG DURING MAXIMAL INSTEP KICKING IN FEMALE SOCCER PLAYERS
Get PDFThe purpose of this study was to investigate the effect of knee motion of support leg during maximal instep kicking on female soccer players. Their kicking motions were recorded by a motion capture system. The range of motion of knee angle (knee variation) was caluculated. There were significant negative relationships of foot velocity with knee variation (r =0.73, p \u3c 0.05). The participants were divided into small (n = 8) and large (n = 8) variation groups based on their change amount of support leg knee angle during forward swing. Foot velocity, vertical hip velocity of kicking leg, and vertical centre of pelvis displacement during forward swing phase of small knee variation group than those of large variation group were found significant differences (p \u3c 0.05). These results suggested that training for female players should focus on reducing knee angular displacement (flexion) of support leg during forward swing phase in instep kicking
INFLUENCE OF SHOOT FORCE ON MOTION VARIABILITY OF TOP SNOOKER PLAYERS
Get PDFThe purpose of this study was to determine the influence of shooting with different force on motion variability of top snooker players. Six professional male players shot with hard force shot (HF) and soft force shot (SF), then coefficient of multiple correlations (CMC) and coefficient of variation (CV) were calculated. In SF, flexion-extension (p=.045) and adduction-abduction (p=.001) of shoulder showed higher CMCs than HF and adduction-abduction (p=.042) of shoulder showed lower CV than HF. In SF, flexion-extension of wrist showed higher CMC (p=.035) and lower CV (p=.030) than HF and adduction-abduction of wrist showed higher CMC (p=.039) and lower CV (p=.036) than HF. There was no difference in CMC and CV of cue. Thus hard force shot might increase motion variability of upper limbs
THE EFFECT OF DELIVERY METHOD ON CRICKET BATTING UPPER-BODY KINEMATICS
Get PDFThe aim of this study was to determine the effect of delivery method on upper-body kinematics in cricketers playing a front foot drive and a back foot pull shot. Fourteen male cricketers were played both shots against a bowler, bowling machine, and SidearmTM ball thrower. The availability of pre-release visual cues appears to affect upper-body kinematics during the pull shot but not the drive other than at the back shoulder. The SidearmTM may represent a compromise between bowler and bowling machine when training the pull shot but coaches should consider differences in upper-body proximal-distal joint dominance
CASE STUDY OF AN ACCIDENTAL ANKLE TWIST: A KINEMATIC ANALYSIS USING FUNCTIONAL DATA ANALYSIS
Get PDFThis study examined an accidental ankle twist occurring during a single-participant study of the effects of traction on ankle biomechanics. One male participant performed a series of randomly distributed side-cuts and turns. In the 11th trial, the participant twisted his ankle during a side-cut. As no injury occurred, another 24 side-cut trials were recorded. Functional Data Analysis (FDA) demonstrated that the ankle twist trial was characterised by a sudden increase in inversion and internal rotation along with rapid transition from plantarflexion to dorsiflexion. Velocities showed a two-step increase in internal rotation and inversion, exceeding a 300 °/s safety threshold. The shift to dorsiflexion is indicative of an unloading mechanism that likely prevented the injury. FDA revealed variations between the ankle twist and the control that could inform stud design to prevent injuries
THE RELATIONSHIP BETWEEN TRUNK KINEMATIC VARIABLES AND UNDERWATER UNDULATORY SWIMMING PERFORMANCE IN COMPETITIVE SWIMMERS
Get PDFThe purpose of this study was to examine the relationship between selected trunk kinematic variables and undulatory underwater swimming performance in competitive swimmers. Eight male and 2 female swimmers performed 15 m UUS with their maximum efforts. Three-dimensional coordinate of markers attached to bony configurations were corrected during Pearson’s product moment by using the underwater motion capture system. The range of motion and the corresponding angular velocity were computed for lower waist, upper waist and chest. The relationship between horizontal velocity of center of mass and each kinematic variable was then examined. No significant correlations were found between horizontal velocity and each range of motion. The horizontal velocity was significantly correlate with the angular velocity of lower waist and of chest, but not with the corresponding value of upper waist. The current results suggest that the swimmers produce the great horizontal velocity by increase in trunk angular velocities rather than by increase in trunk range of motion
DYNAMIC CONTRIBUTIONS OF SUPPORT LEG JOINT TORQUES TO THE GENERATION OF THE IPSILATERAL KNEE JOINT MOTION AND GROUND REACTION FORCE IN SPRINTING
Get PDFThis study aimed 1) to quantify the contributions of the support leg joint torques to the generation of the anteroposterior forces, and 2) to clarify major contributors to the support leg knee joint angular velocity in terms of generating factors of the motion-dependent term (MDT) in sprinting. Dynamic contributions of the support leg joint torques in the maximal speed sprinting for elite and sub-elite sprinters were calculated, and the generating factors of the MDT were quantified The results showed that 1) ankle plantar flexion torque is the largest contributor to the generation of propulsive force regardless of performance level, and 2) the major contributors to the support knee flexion for sub-elite sprinter were ankle plantar flexion and hip flexion torques
THE SPECIFICITY OF STRENGTH EXERCISES FOR SPRINT ACCELERATION
Get PDFThe purpose of the study was to use musculoskeletal modelling to examine the specificity of bounding and loaded countermovement jumps (CMJ) to sprinting acceleration. Ten male participants performed 10 m sprints, continuous bounding, and loaded CMJ’s. A generic OpenSim model was scaled to each individual and used to calculate joint moments, angles and angular velocities during maximal trials in each condition. Peak moment, angle at peak moment and angular velocity at peak moment for the ankle, knee, and hip joints were determined and statistically analysed using pair-wise equivalence and non-inferiority tests. Compared to sprinting, peak moments at all joints were shown to be statistically non-inferior for bounding, but statistically inferior for loaded CMJ’s. Compared to sprinting, knee and ankle joint angular velocities were statistically equivalent for bounding, but statistically different for loaded CMJ’s. In terms of the specificity for strength and conditioning exercises, these results suggest that bounding may be considered as a specific exercise for acceleration, while loaded CMJ’s may be less suitable
KINEMATIC CHARACTERISTICS OF RESISTED SLED SPRINTS UNDER DIFFERENT LOADING CONDITIONS
Get PDFThe purpose of this study was to identify the kinematic characteristics of resisted sled sprinting under different loading conditions (0%, 10%, 20% and 30% velocity decrement (Vdec)) and in different sporting populations. Thirty-three healthy athletes (Sprinters n=10; Invasion team sport athletes n=23) were recruited and completed 3 days of testing. Kinematics were captured with high-speed cameras and processed using Dartfish Software. Loads of 20% and 30% Vdec resulted in a significant increase in trunk lean relative to unloaded sprinting, during both acceleration and maximum velocity phases, with no difference between groups (sprint & team sport athletes). This increase in trunk lean with load (20% and 30% Vdec) appeared to prevent athletes transitioning into upright maximum velocity mechanics, and therefore extended the distance of the acceleration phase. The trunk lean increase was related to the heavy loads and athletes were not able to reach mechanics that were truly reflective of maximum velocity (maxV) sprinting. However, heavy loading extended the distance over which it is possible to train acceleration
AMPLITUDE EVALUATED WITH HEAD-TOE DISTANCE IN RELATION TO WHERE CIRCLES ARE PERFORMED ON POMMEL HORSE
Get PDFGymnastic judging is likely to integrate an objective measurement, so appropriate performance variables will become critical for fair and valid judging. As noted in literature, head-toe distance (HTD) is a potential variable to evaluate the amplitude of horizontal rotation on pommel horse performances. This study investigates how HTD varies when circles were performed on different positions on the pommel horse. Kinematic data for eight different types of circles performed by three gymnasts were recorded using a Kinect set that was placed above the pommel horse during regular training. As a result, the different profile of HTD were found depending on where the gymnasts performed circles, demonstrating the possible influences of types of circles on HTD. The importance of better understanding and careful use of such a performance variable was emphasised