5954 research outputs found
Sort by
EFFECTS OF TASK CONSTRAINTS ON SIDESTEPPING JOINT KINETICS
Get PDFThe purpose of this study was to assess the change in lower limb joint kinetics associated with anterior cruciate ligament injury (ACL) risk in sidesteps with and without task constraints. Female athletes (n=21) performed pre-planned and unplanned sidesteps with and without task constraints to the trunk and the preparatory step. Statistical differences in negative peak joint power for the hip, knee and ankle during the execution step, the entry velocity and the sidestep angle between the constrained and unconstrained sidesteps were determined with a linear mixed model. The entry velocity decreased for all unplanned sidesteps compared to pre-planned sidesteps. Trunk constraints increased knee joint loading in pre-planned sidesteps (-24.51 ± 11.27 W·kg-1) compared to unconstrained unplanned sidesteps (-17.69 ± 8.58 W·kg-1). Understanding how constraints can alter the magnitude of lower-body joint loading can help design effective drills to overload single-joint capacities
ANALYSIS OF THE TRIPLE PIROUETTE OF PROFESSIONAL CLASSICAL BALLET DANCERS
Get PDFClassical ballet pirouette is difficult technique to master even for professional dancers. Little research has been conducted on the pirouette. The purposes of this study were to analyse the pirouette movement of professional classical ballet dancers, and to search critical viewpoints for instruction focusing on their averaged motion (Ae et al.,2007) and motion variation of body segments. The participants were 11 professional female classical ballet dancers performed the triple pirouette. The motion capture system with 12 cameras (Qualisys, Sweden, 250 Hz) was used to collect three-dimensional coordinate data. The coefficient of variation (CV) and standard deviation of the body segments were used to represent the variability of body segment movement. There were smaller motion variations in the shank, thigh, head, and torso of the top dancers, which indicated that the similar motion patterns appeared in the triple pirouette in these segments. On the other hand, the larger variation of the left foot in the preparation and turning phase indicated that ankle adjustment may be employed to maintain balance. The upper extremity with large variation may also function as an angular momentum generator and balance adjustor and may be an indicator of difference in teaching methods
HEAD IMPACTS DURING SPARRING: DIFFERENCES AND SIMILARITIES BETWEEN MOUTHGUARD, SKIN, AND HEADGEAR SENSORS
Get PDFThe timely identification of concussions is essential to ensuring athlete safety. In contact sports, many devices are available to measure head impacts, but concerns remain regarding their ability to accurately estimate the number and magnitude of those impacts. This study measured head impacts during boxing sparring simultaneously with three sensors – a mouthguard, a skin patch and a headgear patch – and video analysis. The objective was to assess and compare the number, quality, and magnitude of impact events across sensor types. All sensors had issues related to decoupling from the skull, although the mouthguard appeared to generate better estimates than the patches of the number of impacts and impact-induced head kinematics
IDENTIFICATION OF THE POP-UP ACCELERATION WAVEFORM SIGNAL: A CASE STUDY
Get PDFThe purpose of this case study was to assess the feasibility of using accelerometers to identify and analyse the acceleration waveform signals of the pop-up movement. An experienced male recreational surfer performed 10 dry-land pop-ups with accelerometers (1000 Hz) attached to the sacrum and lateral aspect of each shank. The waveform signals of the pop-up were successfully identified at each instrumentation site using a combination of acceleration and video data. Several movement events that occurred during the pop-up were also able to be detected within each of the mean resultant acceleration signals. These findings suggest that accelerometers can viably be used to detect and analyse the waveform signals of the pop-up. This provides initial evidence that accelerometers are a suitable tool for collecting kinematic data of surfing performances
VISUAL DETECTION OF RESPONSE TIME IN ATHLETICS: A “GOLD STANDARD”?
Get PDFThe response time (RT) in the sprint start in athletics is determined automatically from sensors on the blocks but the final decision on whether an athlete is disqualified is determined by visual inspection of the sensor data. This study explored the level of uncertainty of the visual detection of athletes’ RT in the sprint start. Fifteen sprinters performed six sprint starts while forces from the front block, rear block and hands were recorded. Two experimenters performed visual RT detection on two consecutive occasions using two sizes for the analysis window. Intra- and inter-reliability analysis indicated that the mean level of uncertainty of the visual detection was approximately 20 ms for the starting block data. More research is needed to formally assess the precision of the visual detection, which may result in changes in the current false start regulation
CHANGES IN LUMBAR JOINT MOMENTS USING A FEMALE SPECIFIC TORSO AND DYNAMIC BREAST MODEL DURING RUNNING
Get PDFThis study aimed to investigate the effect of breast mass and motion on lumbar flexor / extensor moments during running. Kinematic and kinetic data were collected for a female participant running at 2.6 m/s. An MRI scan was used to calculate breast mass and centre of mass location. An OpenSim model was customised with two point-mass segments added to the torso to represent the breasts. Three model variations were constructed (combined breast and torso mass; separate breast and torso mass without breast motion; separate breast and torso mass with breast motion). Findings show that neglecting breast motion causes peak lumbar extensor moments to be underestimated by ~3.4%, compared with a combined breast and torso mass model. These results highlight the importance of including breast motion in female specific MSK models, during activities such as running
ARE FUNCTIONAL MOVEMENT PATTERNS PRECURSORS TO FUNCTIONAL PERFORMANCE IN UNIVERSITY WOMEN’S SOCCER PLAYERS?
Get PDFFunctional movement patterns (e.g., stepping, lunging) underlie higher-order skills (e.g., throwing, jumping). Thus, better jump performance may be associated with higher Functional Movement Screen (FMS) scores. We examined this relationship in 25 female university soccer players. Pearson Correlation was used to determine associations between FMS scores (out of 21) and CMJ height (cm), reactive strength (RSI-mod, m/s), and peak concentric, eccentric and landing forces (N/kg). FMS (14.68 ± 2.43) was moderately associated with jump height (23.78 ± 5.94 cm), r(23)=0.54, p≤0.05 and RSI-mod (0.22 ± 0.06 m/s), r(23)=0.44, p≤0.05. University women’s soccer players who had higher FMS scores also jumped higher and had greater reactive strength. Ensuring functional movement pattern proficiency may enhance CMJ performance
BIOMECHANICS AND MOVEMENT PATTERN DEFICITS IN RUNNERS ON THE SAME UNIVERSITY TEAM: IMPLICATIONS FOR PREVENTATIVE SPORT HEALTHCARE
Get PDFWe sought to describe running kinematics and movement patterns in a university cross country team with relevance to injury prevention. During pre-participation physical examinations, 27 runners underwent Functional Movement ScreenTM (FMS) and motion analysis of running kinematics [bilateral knee flexion (KFLEX) and ankle dorsiflexion (ADF) at initial contact, and hip adduction (HADD), contralateral pelvis drop (CPD), KFLEX, rearfoot eversion (REV), and ADF at midstance]. Results of HADD (Left 10.5 ± 3.80, Right 11.2 ± 5.20), CPD (Left -7.1 ± 2.80, Right -6.0 ± 2.10) and REV (Right 4.4 ± 3.90, Left 5.0 ± 4.00) at midstance and FMS (13.7 ± 2.4) indicate the need for team based injury prevention. Sport healthcare providers in team settings may benefit from these analyses
STIFFNESS COMPARISON OF RUNNING PROSTHETIC FEET OF DIFFERENT CATEGORIES AFTER BENCH TESTING
Get PDFThe purpose of the work is the comparison of stiffness properties of Running Prosthetic Feet (RPF) for transtibial amputee athletes after the introduction of test methods to collect and analyse their Load-deflection curves. The study explores the effect of the orientation of the socket (ϑG) with respect to ground during a load cycle.The three Ossur feet Cheetah Xtreme Category 4th, 5th ,6th underwent extensive testing on a multi-component test bench. Results show that the unit interval between categories does not matches with the interval in terms of equivalent stiffness Keq introduced as synthetic stiffness parameter
IS PERCEPTION OF VAR OUTCOME BIOMECHANICALLY ACCURATE?
Get PDFThe purpose of this study was to understand if offside judgments, using different video assistant referee (VAR) technologies (video replay vs. guiding lines), are biomechanically accurate. Ten college students viewed video clips of a football player, receiving the ball from his teammate, and from different camera angles. Participants were asked to determine the ball-kick moment and to judge whether the ball receiver was in offside. Participants’ responses were verified with the kinematic parameters of the ball and the players. Participants’ judgements were on average 132 ms later than the actual offside moment. While camera angles did not affect their judgements, participants had higher correct judgments at 0 and 90° viewing angles and when VAR guiding lines were present