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PREDICTING 3D GROUND REACTION FORCE FROM 2D VIDEO VIA NEURAL NETWORKS IN SIDESTEPPING TASKS
Get PDFSports science practitioners often measure ground reaction forces (GRFs) to assess performance, rehabilitation and injury risk. However, recording of GRFs during dynamic tasks has historically been limited to lab settings. This work aims to use neural networks (NN) to predict three-dimensional (3D) GRF via pose estimation keypoints as inputs, determined from 2D video data. Two different NN were trained on a dataset containing 1474 samples from 14 participants and their prediction accuracy compared with ground truth force data. Results for both NN showed correlation coefficients ranging from 0.936 to 0.954 and normalised root mean square errors from 11.05% to 13.11% for anterior-posterior and vertical GRFs, with poorer results found in the medio-lateral direction. This study demonstrates the feasibility and utility of predicting GRFs from 2D video footage
PRINCIPLE COMPONENTS ANALYSIS TO CHARACTERIZE STRESS, PERFORMANCE, AND INJURY IN FEMALE COLLEGIATE SOCCER PLAYERS
Get PDFStress created by training is needed to elicit physiological adaptations to increase performance, however, a stress threshold exists. We assessed 19 female collegiate soccer players during an eleven week preparatory phase and measured stress, performance, and injury variables. We used a principal component analysis to determine relationships among stress, performance, and injury. We found a weak, negative relationship between practice stress and anaerobic stress (r = -0.107, p = 0.05), a positive relationship between anaerobic stress and movement risk of injury (r = 0.459,
COORDINATION VARIABILITY AND INJURY RISK IN EXPERIENCED COLLEGIATE DANCERS
Get PDFDance is a sport that places a number of physical demands upon the human body, and injuries are a common occurrence in the sport. While it has not yet been linked to dance-related injury, coordination variability (CV) is a measure of how much movement strategy changes between repetitions of a task and low levels of CV have been linked to injury in other sports. This study aimed to determine the relationship between CV and dance injury in collegiate dancers. Eight (8) undergraduate student subjects were recruited from the dance major and minor, BFA major and minor, and recreational dancers who engaged in \u3e3 hours of dance per week. At intake dancers completed 10 trials of a sauté jump task to measure baseline CV using a modified vector coding (MVC) approach. Dancers then completed 4 months of weekly check-in forms to report any and all injuries sustained during the week and number of hours spent dancing. Analysis revealed that in general, non-injured participants tended to have more frequent fluctuations and overall higher CV values than the non-injured group, especially in couplings 1 (p = 0.052, effect size 2.31) and 3 (p = 0.31, effect size 1.59). Hours per week spent in dance and years of experience did not appear to have any effect on injury status. This study highlighted certain trends which point to a relationship between lower coordination variability and injury in dancers. This research serves as a beneficial study to examine the role of CV in sports injury
TROPHIC ECOLOGY OF JUVENILE LEAN AND SISCOWET LAKE TROUT (SALVELINUS NAMAYCHUSH) FROM U.S. WATERS OF LAKE SUPERIOR
Get PDFIn this study, I investigated the spatial overlap, diet similarity, and isotopic niches of juvenile Lean and Siscowet Lake Trout ecotypes across six ecoregions of Lake Superior. Spatially, Lean and Siscowet were observed in overlapping depth distributions. Leans were most abundant in shallow waters (60m). The greatest levels of cohabitation were observed in waters from 40-60m. Trophic position (as measured by δ 15N) was similar for both ecotypes at small sizes (mm), but Siscowet exhibited a higher trophic position than Lean Lake Trout at larger sizes (\u3e400mm) and older ages (\u3e5 years). Base of production (as measured by δ 13C) was similar for small Lean and Siscowet. Isotopes of sulfur (δ 34S) indicated the profundal-benthic pathway was more important for Siscowet whereas Leans were more reliant on pelagic energy sources. Lean Lake Trout exhibited greater length-at-age relative to Siscowet. However, Lean Lake Trout length-at-age was negatively related to regional levels of diet similarity and niche overlap. I provide evidence that an ontogenetic shift in which Siscowet Lake Trout shift to feeding in deeper habitats at 400mm or age-5 facilitates resource partitioning between larger and older Lake Trout ecotypes
Evaluating the Undesired Outcomes of Response Interruption and Redirection
Get PDFStereotypy is commonly defined as “frequent repetition of the same, typically purposeless movements, gestures, vocal sounds or utterances”, (Merriam-Webster Collegiate Dictionary, n.d.) and is a common perseverative behavior that is observed among children with autism spectrum disorder and other developmental disabilities. Stereotypy may result in interference with educational and therapeutic activities for the child. The present study sought to determine if the punishment procedure, response interruption and redirection (RIRD), is effective in reducing stereotypy during natural environment training without demonstrating other undesired behaviors that are associated with punishment procedures, including aggression, avoidance of staff, etc. Results of this study indicated that RIRD was effective in reducing stereotypy for one participant, and did not result in increased aggression, avoidance of staff, or decreased appropriate vocalizations for either of the participants
Health Disparities Between Women and Men in Medieval Europe: a Bioarcheological Study of Gender Roles
Get PDFANALYSIS OF RUNNING MOTION IN THE STARTING PHASE OF MALE SKELETON ATHLETES AT INTERNATIONAL COMPETITIONS
Get PDFThe purpose of this research was to assess which kinematic factors were related to running speed in the starting phase for international-level skeleton athletes during races. The starting motion of 22 male athletes was recorded with four video cameras during competitions and their starting motion was analysed by a three-dimensional direct linear transformation method. The maximum angular velocity of the thigh increased from the 2nd to the 3rd step. The maximum hip extension angular velocity of the support leg gradually increased up until the 6th step while the maximum knee extension angular velocity remained constant throughout. It would appear that international-level male skeleton athletes employed an increase in thigh motion and quick hip and knee extension for the support leg to obtain a large running speed
BIOMECHANICAL AND PHYSICAL PROFILE COMPARISON IN MILITARIES WITH AND WITHOUT MUSCULOSKELETAL INJURIES: A PRELIMINARY STUDY
Get PDFThis study compared limb strength, body composition, cardiorespiratory fitness and vertical jump performance in military staff with and without prior musculoskeletal injures. Thirty male military personnel enrolled in a physical education undergraduate program participated in this study. A survey covering history of the last two years of musculoskeletal lower limb injuries was sent to participants, who were separated into groups: injured (IG; n=16) and uninjured (NIG; n=14). Participants performed a sit and reach flexibility test, body composition, 12-min Cooper running test, vertical jump performance and back squat in a smith machine on five different days. Participants from the IG presented reduced strength and vertical jump performance compared to the NIG. No differences were observed in body composition, or cardiorespiratory fitness between groups
ANALYSIS OF THE SERVING MOTION OF MALE COLLEGE TENNIS PLAYERS IN A SIMULATED MATCHES
Get PDFThe purpose of this study was to analyse the serving motion of the nineteen male college tennis players in simulated matches, and to seek for critical points for the improvement in the techniques by comparing with that of the world-class players reported by Fleisig et al. (2003) and Michikami (2014). The variables used in this study were the ball speed, racket speed, angles and angular velocities of the upper and lower limbs. Ball speed and racket speed for the male college players were significantly lower than that of the world-class players. The peak angular velocities of the right shoulder internal rotation and the left knee extension were lower in the male college players than those of the world-class players. For the improvement in the ball speed in serve, the critical points identified would be large angular velocities of the shoulder internal rotation and the knee extension