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DEVELOPING A NEW PERFORMANCE MEASURE TO QUANTIFY THE DIFFERENCE BETWEEN ACTUAL AND PREDICTED ON-WATER ROWING PERFORMANCE
Get PDFThis study developed a measure of on-water rowing performance (on-water delta) that quantifies the difference between actual on-water performance and on-water performance as predicted from ergometer performance. Maximal effort 2000 m ergometer and on-water times (n = 340) were collected from 162 athletes over a 16-year period. A linear mixed model was fitted to the dataset to enable predictions of on-water performance from ergometer performance whilst accounting for repeated measures and other factors such as potential environmental effects. On-water delta was defined as a model residual and ranged from -32.8 s (overperformed) to 51.1 s (underperformed). On-water under or overperformance compared to that predicted from ergometer performance could provide valuable context for future biomechanical investigations of on-water rowing technique
MARKERLESS MOTION CAPTURE AND OPTIMAL CONTROL TO INFORM PITCHING MECHANICS AND REDUCE INJURY RISK
Get PDFThe objective of this study is to demonstrate the utility of predictive musculoskeletal simulations in baseball pitching. An optimal control analysis was developed that aimed to minimize injury risk while maintaining pitching performance. The optimization converged on a solution that reduced peak shoulder internal rotation by 27.1% while maintaining peak hand velocity within 1.7%. The optimized simulation suggested that 1) a lower arm slot 2) greater knee extension in the stride leg would lead to reduced injury risk without degrading performance. This study\u27s findings demonstrate the potential of biomechanical analyses in enhancing performance and reducing injury risks in baseball pitchers
THE EFFECT OF TOUCHDOWN KINEMATICS ON FORWARD ACCELERATION IN THE SKELETON PUSH START
Get PDFProducing forward acceleration in a bent-over position while pushing a sled is poorly understood. Therefore, the purpose of this study was to investigate body and segment orientation of 16 elite skeleton athletes for the ground contacts 1 to 3 after the start and after 15 m as well as to quantify their relation to forward acceleration. Kinematic and kinetic data were recorded indoor on an athletics track whilst the athletes were pushing a sled dummy along guiding rails. Trunk and thigh orientation remained similar during the acceleration phase, while changes in touchdown kinematics originated from the shank and foot segment. Variance in forward acceleration could be sig. explained by shank orientation (R²adj = 0.84). Consequently, training interventions to modify shank orientation in skeleton should be developed
A PRACTICE-ORIENTED TEACHING STRATEGY INVOLVING BOULDERING IMPROVES STUDENTS’ ACADEMIC UNDERSTANDING OF MECHANICS
Get PDFPractical experience is recommended in teaching to overcome students’ difficulties in learning and applying theoretical concepts such as Newtonian mechanics. The purpose of this study was to test whether incorporating bouldering in a biomechanics course improves students\u27 academic understanding of mechanics. Twenty-one students participated in 10 weeks of traditional lecturing and a subsequent 4-week bouldering intervention. Using different versions of a validated biomechanics test, exam scores were higher after bouldering (73±15%) than before (53±21%) (Z=-3.783,
KINEMATIC COMPARISON OF OPENCAP AND IMU WITH MARKER-BASED MOTION CAPTURE IN TREADMILL RUNNING: A PILOT STUDY
Get PDFThe purpose of this pilot study was to compare lower-limb running kinematics measured using a markerless system, OpenCap, and inertial measurement units (IMUs) against the marker-based motion capture (mocap) system. One participant ran at 2.22 m/s on a treadmill for one minute. Mean absolute error (MAE) and root mean square error (RMSE) of hip, knee, and ankle flexion were calculated independently for all 3 devices. Time synchronization of devices was facilitated by performing a ‘kick’ and identifying its peak knee angle prior to running. Offset correction was also applied to OpenCap and IMUs data to match those of marker-based mocap data at the start of time synchronization. OpenCap exhibited a higher degree of error than IMUs in all joint angles compared to marker-based mocap both before and after an offset correction was applied, with errors exceeding 10°
TRANSITION TO A HEAVIER BALL IN TEN-PIN BOWLING
Get PDFThis study investigated how developmental ten-pin bowlers can better transit to a heavier ball by comparing differences in performance outcomes and movement execution between two ball weights. Eight pre-transited bowlers bowled 10 first-frame trials each in two ball weight conditions: normal (NB) and heavy (HB); of which 3 trials were analysed. Full body joint kinematics were recorded via a 3D motion capture system. Paired sample t-test on performance outcome, joint kinematics and kinetics was conducted. No differences in performance outcome and peak joint velocities were found (p\u3e0.05). Bowling with the HB resulted in higher peak elbow extension moment and quicker third step, with differences in left shoulder rotation and ankles abduction during the movement (
DETERMINATION OF GAIT EVENTS FROM 2D VIDEO USING LONG SHORT-TERM MEMORY NEURAL NETWORKS
Get PDFThe purpose of this study was to automatically identify the key gait events, foot-strike and foot-off, from 2D video data. Markerless motion capture and pose estimation have become accepted tools in many biomechanics applications to automatically analyse 2D videos of human movement. However, the accurate detection of gait events from various camera views is still a challenge. We trained a long short-term memory neural network to identify foot-strike and foot-off events in walking and running trials captured from nine different camera views based on 2D pose estimation keypoint labels. We achieved a detection accuracy of 86.3-96.1% (F1 score 76.2-92.5%). These results show the applicability of machine learning tools for the automatic detection of key event frames, which will help practitioners to easily identify frames of interest for further biomechanical analyses
The Near Normality of the Commutant of a Moufang Loop
Get PDFWe investigate conditions under which the commutant of a Moufang loop is normal and related topics. We begin by giving relevant background on Moufang loops and normality. We then prove a theorem showing how close the commutant is to being normal: cR(x, y)R(x, y)R(x, y) = c. We then prove a couple of theorems emphasizing the importance of cubes in Moufang loops. Finally we prove a decomposition theorem for the multiplication group of a finite commutative Moufang loop
Environmental DNA (eDNA) Metabarcoding: Analysis of Freshwater Macroinvertebrate Community Structure and Diversity
No full textMacroinvertebrate identification via morphological surveys requires significant time, manpower, and expertise. These constraints can limit measures of biodiversity, and thus, new methods of macroinvertebrate sampling are being explored. Environmental DNA (eDNA) metabarcoding, which can be used to identify the taxonomic composition of entire communities, has the potential to increase both survey efficiency and taxonomic resolution. In this study, I evaluated the efficacy of eDNA metabarcoding to document freshwater macroinvertebrate diversity in two watersheds (Whetstone Brook watershed and Orianna Brook Watershed) and one drainage ditch in Marquette County (MI, USA). I performed eDNA sampling to determine community richness and variability within and among each watershed, and I targeted cytochrome c oxidase I (COI) for amplicon sequencing. I analyzed the resulting alpha and beta biodiversity indexes to assess the ecological distribution of freshwater macroinvertebrates and found that freshwater macroinvertebrate community composition was significantly different among sites, where evidence of high taxa turnover suggests spatial and temporal drivers of community assemblage. Overall, my results indicate that the taxonomic data provided by eDNA metabarcoding can detect fine-scale variation at a local scale, suggesting that this method is a promising molecular technique for surveying freshwater macroinvertebrate biodiversity