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THE INFLUENCE OF WARM-UP EXERCISES ON KNEE AND ELBOW JOINT MOTION FOR STANDING LONG JUMP PERFORMANCE
Get PDFThe purpose of this study was to analyse the influences of the motion angles of the knee and elbow joints on the standing long jump performance of high school students. Twenty-nine participants were assigned to either a control group to perform static and dynamic joint exercises or an experimental group to perform basic sprinting drill warm-up exercises. Both groups performed pre-, control, and post-standing long jump tests. Motion analysis of the knee and elbow joints was conducted in the sagittal plane by using video recording. Our findings support that basic sprint drill warm-up exercises can enhance the jump length in the youth. The implementation of warm-up exercises with basic sprint drills and motion analysis could be useful for determining the ranges of motion of the elbow and knee joints and improving standing long jump performance
USING TRACKING TECHNOLOGY TO ESTIMATE BALL SPIN IN TENNIS
Get PDFThe purpose of this study was to examine the ability of a physical model to estimate the spin of trajectories measured by a multi-camera ball tracking system. Ball spin rates and spin axis estimated from theoretical ball trajectory models were assessed for their accuracy against high-speed vision (the ground truth). A trajectory model applied to ball tracking data was able to estimate ball spin axis direction with high accuracy and ball spin rates with an RMSE of 219.47 RPM. With tracking technology now common place during professional level tennis matches, the use of a trajectory model provides a non-invasive method to accurately estimate the spin imparted when hitting
FATIGUE ALTERS THE BIOMECHANICS OF TURNS WHILE RUNNING
Get PDFThis study identified the effects of fatigue on lower limb kinematics while running with repeated 180°-turns. An increased stiffness of the pivoting limb was observed in terms of a reduction of hip and knee flexion angles, and an increase of hip abduction and internal rotation. We concluded that muscle fatigue can trigger a sequence of adaptations that were previously found to expose the athlete to an increasing risk of ligament injury. These results expand the base of evidence for the development of field-based prevention programs
LATE SWING KNEE MECHANICS IN ELITE RUGBY UNION PLAYERS AND TRAINED SPRINTERS
Get PDFHamstring injuries are highly prevalent in running-based sports such as sprinting and rugby union, and are thought to occur during the late swing phase where the hamstrings are under great load and strain. The aim of this study was to investigate the knee mechanics of elite rugby players and speed-matched sprinters during the late swing phase of maximum effort over-ground running. Elite rugby players demonstrated reduced knee extension velocity through late swing, which was associated with a smaller maximum knee flexion angle during the mid-swing phase. As rugby players displayed a greater absolute knee flexion moment, power absorption and negative work, we suggest that the kinematic differences displayed by rugby players may be an adaptation to reduce the velocity of hamstring stretch and load on the hamstring muscles during late swing
THE INFLUENCE OF FULL FACIAL PROTECTION ON HEADFORM PEAK LINEAR ACCELERATION AT DIFFERENT HELMET IMPACT LOCATIONS
Get PDFThe purpose of this study was to examine the influence of ice hockey helmet facial protection on measures of peak linear acceleration at different helmet locations during horizontal dynamic impacts. A repeated measures factorial ANOVA revealed a two-way interaction effect between type of facial shielding protection and helmet impact location on measures of peak linear acceleration, F (1.53, 26.05) = 18.60, p \u3c .001, h2 = .52. This finding indicates that the type of facial shielding protection can help mitigate linear impact accelerations at different helmet locations and consequently, minimize the risk of head injury. This outcome may have implications for athletes, coaches, and researchers to better understanding helmet performance in brain injury prevention for the sport of ice hockey
KINETICS OF SINGLE SESSION INTRA-INDIVIDUAL DIFFERENCE IN SPRINT ACCELERATION: A CASE STUDY
Get PDFThis case study aimed to investigate inter-repetition differences in joint kinetics for a single athlete during the acceleration phase of sprinting. One well-trained male sprinter performed three maximal effort 40-m sprints in an indoor experimental site. Using the fastest and slowest trials, spatiotemporal, ground reaction forces, and joint moment variables were calculated step to step for 16 steps. The fastest trial was accompanied by the greater mean net anteroposterior force. Moreover, there were greater hip extension and ankle plantar flexion moments, as well as a smaller knee extension moment, in the fastest trial. Accordingly, producing greater hip extension and ankle plantar flexion moments while suppressing the knee extension moment leads to better sprint acceleration through the greater propulsive force in the initial acceleration section
THE BEHAVIOR OF THE MARGIN OF STABILITY DURING ABLE-BODIED TRUNK-FLEXED GAIT
Get PDFThe dynamic margin of stability (MoS), defined as the difference between the anterior boundary of the base of support and the extrapolated whole-body center of mass (WBCM) at foot touchdown, reflects the control of gait dynamic stability. This study explores the behavior of MoS during level walking in able-bodied walkers (n = 10) under altered sagittal trunk orientations, including ~30°, ~50° and maximal trunk flexion from the vertical compared with upright posture. Exploiting compensatory kinematic adjustments (e.g., crouched lower-limbs) possibly allowed participates to control their postural stability, as increasing trunk flexion did not lead to a significant diminish in the MoS relative to regular upright walking. Our findings might be of clinical interest to clinician interested in the nature and impact of alteration in trunk geometry on the control of gait dynamic stability