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CREATING VIRTUAL FORCE PLATFORMS FOR CUTTING MANEUVERS FROM KINEMATIC DATA BASED ON LSTM NEURAL NETWORKS
Get PDFThe precise measurement of ground reaction forces and moments (GRF/M) usually requires stationary equipment and is, therefore, only partly feasible for field measurements. In this work we propose a method to derive GRF/M time series from motion capture marker trajectories for cutting maneuvers (CM) using a long short-term memory (LSTM) neural network. We used a dataset containing 637 CM motion files from 70 participants and trained two-layer LSTM neural networks to predict the GRF/M signals of two force platforms. A five-fold cross-validation resulted in correlation coefficients ranging from 0.870 to 0.977 and normalized root mean square errors from 3.51 to 9.99% between predicted and measured GRF/M. In future, this method can be used not only to simplify lab measurements but also to allow for determining biomechanical parameters during real-world situations
STUDENTS’ PERCEPTION ON TEACHING STYLE AND LEARNING OUTCOME
Get PDFThe purpose of this study was to investigate the influence of active learning on students‘ learning outcomes in undergraduate introductory biomechanics and students‘ preference of teaching style. Five undergraduate biomechanics classes from four public universities in the United States were recruited (N = 204). Survey questions were administered over the internet. A total of 160 valid responses were analyzed. The students who rated their class was somewhat interactive and very interactive had significant learning improvement (p \u3c 0.05). There was no significant learning improvement in groups that rated their classes either pure lecture (p = 0.09) or primarily interactive (p = 0.46). This indicated that moderate amounts of active learning enhance learning outcomes above lecture alone or primarily active learning. Students’ preferred interactive style was hands-on activity
HIP-KNEE COUPLING IN RUGBY PLACE KICKING AT THREE DIFFERENT DISTANCES
Get PDFThe purpose of the study was to investigate hip-knee coupling in rugby place kickers, kicking at three different distances from the posts (40 m, 32 m, and 22 m). An optoelectronic motion capture system consisting of ten cameras was used for capturing total body kinematic data. Data collection took place outdoor, on a rugby field. During the forward swing a period of in-phase is reported as both the hip and the knee were flexing, creating a whip-like action. Even though absolute changes in joint angles of hip flexion and knee extension were seen, no changes were reported for the coordination patterns when kicking at different distances (22 m, 32 m, 40 m), indicating no change in movement strategy when kicking at different intensities
EFFECTS OF MAXIMAL STRENGTH ON GROUND REACTION FORCE PATTERNS DURING COUNTERMOVEMENT JUMPS
Get PDFThe purpose of this study was to determine the effects of maximal strength on ground reaction force (GRF) patterns during countermovement jumps (CMJ). Nineteen female lacrosse players performed CMJ and isometric mid-thigh pulls (IMTP) on force plates. Principal components analysis was used on the CMJ time series data to extract GRF patterns. Maximum GRF during the IMTP were extracted and used as a measure of maximal strength. Spearman’s rho correlations were used to analyse the relationship between maximal strength and GRF patterns during the CMJ. Results suggest that maximal strength is positively correlated to a GRF CMJ pattern characterised by greater rate of force development and peak force as well as less of a decrease in GRF immediately after the end of the eccentric phase (i.e., absence of bimodal GRF profile)
AN ANALYSIS OF THE THROWING TECHNIQUE OF COLLEGE MALE JAVELIN THROWERS IN A COMPETITION
Get PDFThe purposes of this study were to investigate the throwing technique for Japanese college male athletes in official competitions, focusing on the torso and throwing arm motions, and to obtain basic information for the improvement in their techniques. Twenty-four male college throwers were videotaped and analysed for their throwing motion using the three-dimensional DLT method and caluclated the joint angle. The throwers were divided into three groups based on their records. Comparison to the ELITE throwers, the timing of the torso rotation for college groups was delayed. Significant differences in the right shoulder horizontal abduction angle around the left foot touchdown among the three groups were found. These results imply that the right shoulder horizontal abduction may be one of the factor determining throwing distance as well as early torso rotation. The discussion suggested that the concept change from the late rotation to the early rotation of the torso for the college male javelin throwers would result in a large horizontal abduction and a quick horizontal adduction of right shoulder
MOTOR MODULARITY DURING PEDALLING ACROSS DIFFERENT MECHANICAL CONSTRAINTS: A TIME-FREQUENCY ANALYSIS
Get PDFThe purpose of this study was to determine the changes in the time-frequency-muscle synergies across different mechanical constraints during pedalling. Eleven experienced cyclists performed three 1-min bouts of pedalling at 90 revolutions per minute: bilateral (250 W), unilateral (125 W) and effective (250 W). Surface electromyographic (EMG) records from eleven lower-limb muscles were used to extract muscle synergies based on linear envelope (LE) or based on time-frequency features (TF). Three LE muscle synergies accounted for a mean variance accounted for (VAF) of 91.0 % ± 2.3, 90.7 % ± 2.4 and 91.6 % ± 2.4, for the bilateral, unilateral and effective pedalling tasks, respectively. When three TF muscle synergies were extracted, similar muscle groupings were obtained. The main results support the neural origin of the motor modularity
IDENTIFICATION OF FATIGUE-RELATED KINEMATIC CHANGES IN ELITE RUNNERS USING A SUPPORT VECTOR MACHINE APPROACH
Get PDFUnderstanding the kinematic changes underlying fatigue is essential in running biomechanics. The aim of this study was to identify fatigue-related kinematic changes in elite runners using a support vector machine approach. Full-body kinematics of thirteen trained runners were recorded in a non-fatigued and a fatigued state during treadmill running at their individual fatigue-speed. A support vector machine was trained and used to identify kinematic differences between the non-fatigued and fatigued state based on principal component scores. Strides during non-fatigued and fatigued running could be separated with 99.4% classification accuracy. Four upper limb (two shoulder and two elbow), four lower limb (one ankle, two knee and one hip) and two trunk (one thoracic and one lumbar spine) principal component scores were identified as most discriminative kinematic features between non-fatigued and fatigued running. The findings of the study suggest the feasibility of a support vector machine approach to identify subtle fatigue-related kinematic changes in elite runners
PEAK LOWER EXTREMITY NET JOINT MOMENTS AND JOINT ANGLES DURING ISOMETRIC MID-THIGH PULLS VARY WITH BAR POSITION
Get PDFThe purpose of this study was to identify the effect of bar position on the ankle, knee, and hip peak net joint moments (NJM) and associated joint angles during isometric mid-thigh pulls (IMTP). Seven female college lacrosse players performed maximal IMTP at three different bar positions (low: above patella, mid: mid-thigh, high: crease of hip) while motion capture and GRF data were recorded. Inverse dynamics was used to calculate peak ankle, knee, and hip NJM. Joint angles at peak NJM were also extracted. Main effects for bar position existed for hip NJM and hip and knee joint angles. Pair-wise comparisons showed that hip NJM differed significantly between all positions. Strength and sports coaches should consider these results when they use the IMTP to assess and monitor maximal strength as part of their conditioning programs
A COMPARISON OF THE NATIONAL FOOTBALL LEAGUE COACHES STRENGTH AND CONDITIONING PRACTICES 1997-1998 TO 2018
Get PDFThis study describes the results of a survey of the strength and conditioning practices of the National Football League’s (NFL) strength and conditioning (S&C) coaches. The primary purpose was to identify the common and unique aspects of the NFL S&C practices during 2018. A secondary purpose was to compare those results to 1997-1998 (‘97-98) to determine differences across years. The survey response rate was 28.1% (9 of 32 NFL teams) agreeing to participate. The survey instrument was a 150 item assessment divided into 10 sections examining the entire training program. Results revealed that subjects test 6.8 ± 3.1 fitness variables using 9.0 ± 3.7 tests; compared to 7.0 fitness variables using 10.0 tests in ‘97-98. Six subjects prescribe plyometric exercises to “all players” 1.8 ± .4 days per week. During the in-season subjects prescribed resistance training 2.3 ± .8 days per week (n=6); similar to 2.8 ± 0.8 days per week in ’97-98 (p= .220). Subjects prescribed off-season resistance training 3.5 ± 0.8 days per week; compared to 2.0 ± 2.9 days per week in ’97-98 (p= .007). Five subjects prescribed “all players” balance and stability training “year round”; on average 3.3 ± .9 days per week (n=4). This data should be useful for future research as a source for comparison. With this new source of information, researchers are able to continue to empirically investigate various aspects of training programing. Additionally, a variety of other S&C practices were examined. This research was funded by two Excellence in Education Research Grants
QUEERING THE CURRICULUM: ESTABLISHING EQUITY FOR LGBTQIA STUDENTS AND EDUCATORS IN MICHIGAN
Get PDFThis project examines the state of Michigan’s efforts in creating an equitable learning and working environment for LGBTQIA K-12 students and educators, explicitly focusing on 11th and 12th grade English Language Arts (ELA) standards. In the first chapter, I evaluate the relationship between queer theory and pedagogy and illuminate the need to implement queer pedagogy in teaching K-12 ELA classes. The following chapter reviews the progressive state of California for its promotion of culturally responsive pedagogy and its inclusion of LGBTQIA topics in its K-12 curriculum. The third chapter analyzes Michigan legislature and policies to highlight gaps that allow for the perpetuation of heteronormativity. This chapter also acknowledges efforts the state of Michigan has undertaken to improve the LGBTQIA community’s experiences in the education system. The subsequent chapters detail specific measures that must be taken to fill the gaps that Michigan leaves open. I discuss how those gaps might be filled through the use of queer and culturally responsive pedagogies in ELA classrooms, by reconsidering text selection processes, and also through the restructuring of pre-service education requirements