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RELATIONSHIP BETWEEN GROUND REACTION FORCE AND THROWING ARM KINETICS IN HIGH SCHOOL AND COLLEGIATE BASEBALL PITCHERS
Get PDFThe purpose of this study was to examine the relationship of ground reaction force (GRF) of the drive and stride leg and kinetics of the throwing arm in high school and collegiate baseball pitchers. Several studies have examined the relationship between GRF and ball velocity, but no one has examined the effect of GRF on maximum shoulder rotation torque (MERT) and maximum elbow valgus torque (MEVT). Understanding this relationship will be important to both enhancing performance and avoiding injury. Data that were previously collected during a pitching evaluation were analyzed. Twenty-two high school pitchers and 13 collegiate pitchers had received a pitching evaluation. Multiple regression analysis was used to examine the relationships between variables. Only the drive leg medial force (β = .372, p = .015) and stride leg braking force (β = .401, p = .009) were significant predictors of MERT
BILATERAL JUMP PERFORMANCE IS NOT RELATED TO KINETIC ASYMMETRY IN ELITE AMERICAN FOOTBALL PLAYERS
Get PDFMonitoring kinetic asymmetry may provide coaches with a modifiable variable to improve performance. The purpose of this study was to determine the prevalence and relationship of kinetic asymmetry during a countermovement jump (CMJ) and jumping performance. 26 elite American football players performed drop jumps onto an electronic timing mat and CMJ onto a force plate. Kinetic asymmetry was assessed calculating a symmetry index (SI) from inter-limb peak vertical ground reaction forces at propulsion during the CMJ. Pearson correlation coefficients quantified relationships between SI, reactive strength and jump height from the drop jumps, and jump height from the CMJ, p10%. SI was not significantly associated with any variables. p\u3e.05. Players may compensate for asymmetry in a manner that preserves performance
Reliability of center of pressure measures during successive ski-simulated squat tasks
Get PDFLaboratory assessments of alpine ski tasks have the potential to be an effective initial investigation method prior to more intensive on-snow testing. Research questions involving acute changes elicited by sport-essential equipment would be an ideal application for such investigations. The purpose of the current study was to determine the reliability of a ski-simulated squat task on centre of pressure indices. Successive squat tasks were performed in skis at a ski-simulated rhythm and analysed during four experimental conditions. Reliability analysis via repeated measures ANOVAs and intraclass correlation coefficients resulted in good to excellent reliability of centre of pressure outputs. The current study proposes a laboratory test that is reliable and encompasses biomechanical challenges presented by the alpine ski boot-binding complex
MEASURING RACING WHEELCHAIR SPATIOTEMPORAL VARIABLES USING A PHONE CAMERA: A PRELIMINARY CONCURRENT VALIDITY STUDY
Get PDFThe purpose of this study was to assess the measurement agreement between a low-cost system (phone camera) and a reference optoelectronic system, to measure spatiotemporal variables that may be related to wheelchair racing performance: acceleration phase time, push time, backswing time, and maximal elbow height. Three regular wheelchair racers propelled at maximal velocity on a training roller. The temporal variables had a low disagreement between both systems (bias ± 1.96 std of less than 0.01 s ± 0.02 s), while for the maximal elbow height, a higher disagreement of 0.020 m ± 0.038 m was observed. Future improvements are required especially to measure the maximal elbow height. This method may have long term benefits both for the athletes and research, by including more wheelchair racing athletes in future biomechanics studies
A NEW PARADIGM TO DO AND UNDERSTAND THE RACE ANALYSES IN SWIMMING: THE APPLICATION OF CONVOLUTIONAL NEURAL NETWORKS
Get PDFThis article aims to present the benefits of using a deep learning approach to perform race analyses during domestic and international swimming championships. The procedure currently used to perform these race analyses is mostly manual and requires important human resources to annotate the videos and produce the performance reports. Recent technological and scientific developments now allow using ultra high quality cameras (4K) and machine learning algorithms to automatise the detection of the key events and greatly improve the video processing. Such a process helps the collection of data with a higher accuracy, the deployment of a more flexible and reliable setup, the access to the more variables such as the swimmers‘ instantaneous position and velocity, and the redistribution of the human resources to more effective actions
DEVELOPMENT OF A PROTOTYPE SMART APPAREL TO QUANTIFY RUNNING GAIT IN THE DAILY TRAINING ENVIRONMENT
Get PDFRunning gait kinetics and kinematics can be measured in the lab using force-instrumented treadmills and 3D motion capture. However, these tools are not feasible for use in the daily training environment of recreational and elite runners and track athletes. An inertial sensor-based prototype wearable smart garment (SG) has been developed to solve this problem. The purpose of this study was an initial assessment of SG compared to a force treadmill (FT) where foot-ground kinetics and temporal measures relevant to running were examined. Vertical ground reaction force, step time, and contact time showed “good to excellent” mean absolute percent error (\u3c 6%), while step impulse did not (\u3e 10%). All variables showed strong correlations between SG and FT (r \u3e 0.85). The initial prototype smart garment is a viable option for the measurement of running biomechanics outside of the lab
VALIDATION OF A 5-DOF INSTRUMENTED SPEED SKATE; TOWARDS A POWER METER FOR SPEED SKATING
Get PDFSpeed skates are the most important part of equipment of a speed skater, where weight, rocker and bend are just a few characteristics that are to a high degree individualized. This poses a challenge for any type of research in speed skating where forces have to be measured in a reliable manner. For this purpose, a 5 degrees of freedom (DoF) instrumented speed skate (VU-Skate) has been designed and validated, weighing only 130 gram extra. Skaters use their own blades and shoes, something skaters are very keen on. A calibration tool has been developed to calibrate the 5 DoF. The quality of the data has been validated in 2 ways: 1. With the use of force plates and 2. By comparing the signals to another (also newly developed) Ultra-light Forces sensor. The results are remarkably good. This is the first step in being able to measure power continuously during each stroke
Using literacy quadrants in preparing teachers of writing: Reflective tools for identity, agency, and dialogue.
No full textThe researchers of this hermeneutic phenomenological study applied Colaizzi’s (1978) method to analyze and interpret English Language Arts (ELA) teacher candidates’ (TC) learning experiences with literacy quadrants and narratives while attending secondary writing instruction methods courses in diverse institutional settings. Qualitative strategies of data collection included inquiry-driven activities such as drawing and written reflections to literacy quadrants, as well as oral responses to open-ended questions. TCs, moving from knowledge to action, were reflexive about their literacy and learning experiences and the application of knowledge and practices when preparing to teach English to all students. Analysis of TCs’ narratives showed reliance on prior assumptions about teaching writing, increased reflexive stance toward literacy practices, and improved awareness of their professional identities, efficacy, and agency as teachers
Using literacy quadrants in preparing teachers of writing: Reflective tools for identity, agency, and dialogue
No full textThe researchers of this hermeneutic phenomenological study applied Colaizzi’s (1978) method to analyze and interpret English Language Arts (ELA) teacher candidates’ (TC) learning experiences with literacy quadrants and narratives while attending secondary writing instruction methods courses in diverse institutional settings. Qualitative strategies of data collection included inquiry-driven activities such as drawing and written reflections to literacy quadrants, as well as oral responses to open-ended questions. TCs, moving from knowledge to action, were reflexive about their literacy and learning experiences and the application of knowledge and practices when preparing to teach English to all students. Analysis of TCs’ narratives showed reliance on prior assumptions about teaching writing, increased reflexive stance toward literacy practices, and improved awareness of their professional identities, efficacy, and agency as teachers
GENERAL STRENGTH AND MUSCULAR ENDURANCE: RELATIONSHIP TO V1- AND V2-SKATE SKIING ECONOMY IN COLLEGIATE CROSS-COUNTRY SKIERS
Get PDFIntroduction Cross-country skiing is a power-endurance sport requiring upper and lower body activation for propulsion across the ground. While high aerobic markers such as VO2max and lactate threshold are important performance indicators, recent research has demonstrated the importance of full-body general strength and muscular endurance in skiing success. The purpose of this study was to examine the relationship of strength indices via a full-body series of muscular endurance tests, as well as a general 1-RM strength test, to VO2 skiing economy utilizing the V1- and V2-skate technique.
Methods Oxygen uptake was measured during baseline and economy testing on a specialized skiing treadmill. A paired samples t-test was utilized to determine differences between V1- and V2-skate skiing economy. Correlation analysis was used to identify relationships of strength and endurance indices to skiing economy values. Furthermore, a stepwise regression with resampling cross-validation (25 holdout groups) was performed to determine the best predictor of skiing economy.
Results The results of the study found no significant differences between V1- and V2-skate skiing economy VO2 values (p\u3e0.05), as well as other metabolic variables. Pearson partial correlation analysis controlling for sex revealed weight, V1 RER, V2 RER, and shoulder extension were positively correlated with V2 oxygen uptake (p
Conclusion The crossover point of no significant differences in oxygen uptake between V1- & V2-skate was found to be at a greater velocity and grade than previously reported literature. Less oxygen uptake during V1-skate was an indicator of distance racing performance, as a majority of competition time is spent racing uphill utilizing the aforementioned technique. Greater general strength and muscular endurance were not correlated to greater V1 and V2 skiing economy as hypothesized