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COMPARISON OF SEOI-NAGE TECHNIQUE FOR JUDO ATHLETES OF DIFFERENT SKILL LEVELS
Get PDFThe purpose of the present study was to compare the biomechanics parameters of seoi-nage in judo between highly skilled judo athletes and skilled ones. The motion data of the seoi-nage were collected on three male elite judo athletes and sixteen male student judo athletes using a three-dimensional motion analysis technique. This study found that the anterior-posterior component of the ankle and hip peak velocity of the tori in turning phase were significantly larger in the highly skilled group than the skilled group. In addition, the peak velocities of the ankle and hip were significantly correlated to the peak angular momentum of the tori. The results suggested that it would be useful for judo coaches to pay a greater attention to linear velocity of the lower extremities to evaluate the seoi-nage skill than the knee extension
THE SENSITIVITY OF JOINT KINEMATICS AND KINETICS TO MARKER PLACEMENT DURING A CHANGE OF DIRECTION TASK
Get PDFThe conventional gait model has been used in the analysis of change of direction tasks to identify biomechanical risk factors for anterior cruciate ligament (ACL) injury. Several kinematic and kinetic variables have been associated with increased ACL loading during change of direction. Kinematic and kinetic variable calculations are affected by marker placement. The aim of this study was to determine the sensitivity of joint kinematics and kinetics to marker placement error during a change of direction task. Displacements were applied to the lateral thigh, lateral femoral epicondyle and lateral tibia markers. Statistical parametric mapping was used to examine the effect of these displacements across stance phase. Errors in marker placement within the reported inter-tester variability resulted in significant differences in several kinematic and kinetic variables across large periods of stance phase
COMPARISON OF FASTBALL AND CURVEBALL KINEMATICS AND MUSCLE ACTIVITY FOR ELITE BASEBALL PITCHERS THROWING FROM THE STRETCH
Get PDFThe purpose of this study was to compare the muscle activation patterns for the Biceps Femoris, Gastrocnemius, Triceps Brachii, Biceps Brachii, Upper Trapezius, Lower Trapezius, shoulder rotation, elbow angular velocity, elbow flexion-extension & pelvis rotation between the curveball and fastball. Participants were current elite baseball pitchers. After the placement of electrodes, Maximal Voluntary Isometric Contractions (MVIC) were completed. Significant differences in elbow flexion-extension, shoulder rotation, and pelvis rotation for the stretch curveball when compared to the stretch fastball were found. The increase in muscle activity and the greater than MVIC values indicate that lower extremity muscles are beneficial in incorporating into the pitching literature and play a role in the dynamic muscle strength needed to complete a pitch from a specific delivery
THE PREVALENCE AND CAUSE OF NON-CONTACT INJURY MECHANISMS IN U.S. MEN’S RUGBY-7S
Get PDFThe aim of this study was to prospectively report non-contact injury incidence and causes in U.S. men’s Rugby-7s players (n=446) over 2010-2015, using the Rugby Injury Survey & Evaluation (RISE) methodology. Non-contact injuries (time-loss 25%; medical attention 75%) had higher rates among backs (62%; 28.4/1000ph) than forwards (38%; 23.2/1000ph; RR:1.22; p=0.05). Non-contact injuries resulted in an average of 48.7days (d) absence from sport (classic non-contact 48.1d; other non-contact 77.0d). Acute injuries (85%) were most common during attempts to elude a tackle (31%) and in running/open play (48% overall; from 35% in 2010, 41% in 2011, 52% in 2012, 43% in 2013, 46% in 2014, 70% in 2015). Most non-contact injuries (44%) occurred during the first two tournament matches. These results provide much needed data on Rugby-7s, impacting emerging countries
THE INFLUENCE OF AGE-RELATED FACTORS ON THE VARUS/VALGUS MOMENT CAPACITY OF THE ELBOW MUSCLES OF BASEBALL PITCHERS
Get PDFThe purpose of this study was to investigate how age-related factors may influence the capacity of the muscles to protect the ulnar collateral ligament during baseball pitching. Three-dimensional marker position data from 30 pitchers (across three age groups) were incorporated into a musculoskeletal modeling framework, using OpenSim software. The effect of pitcher size, strength, and mechanics were represented by independent implementations of scaling factors, isometric muscle force values, and joint angles, resulting in 27 model combinations. For each combination, the maximum isometric varus/valgus moments that could be produced by all of the muscles were calculated and evaluated. While we found minimal age-related changes in joint angles, varus/valgus moments were highly sensitive to muscular strength and pitcher size
Anthropometric and physiological factors affecting batted ball speed of adolescent baseball players
Get PDFFifty-seven junior baseball players performed eight swings off a tee to record ball exit speed, as well as tests of grip strength, standing broad jump, lateral-to-medial (LM) jumps, chin-ups and chest pass with a medicine ball. The height, weight and age of each participant was also recorded. All anthropometric and physiological tests were significantly positively correlated with ball speed (p \u3c 0.05). Collinearity between variables meant that only chest pass (R² = 0.70, p = 0.000), body mass (ΔR² = 0.03, Δp = 0.021) and LM jump (ΔR² = 0.04, Δp = 0.005) made independent contributions to a stepwise linear regression. These findings corroborate the expectation that upper body power is a major determinant of batting speed, with leg power adding an additional, independent contribution to performance
ESTIMATION OF GROUND REACTION FORCES FROM KINEMATICS IN SKI-JUMPING IMITATION JUMPS
Get PDFThe purpose of the study was to determine the accuracy and the precision of calculated forces based on inverse dynamics during imitation jumps by comparing the results with force plate data. Ten ski-jumpers performed four imitation jumps on a force plate. Additionally, the vertical ground reactions forces were calculated based on an inverse dynamics (ID) approach using kinematic data from a motion capture system. The average accuracy and precision was found to be 60 N and ± 20 N for the peak vertical force, respectively, and -0.3 cm and ±1.6 cm, respectively, for the average jump height. The mean values for jump height were, respectively. The ID approach is assessed to be feasible for the estimation of vertical ground reaction forces exclusively from kinematic data with sufficient accuracy and precision so it can be used for the development of a universal diagnostics tool for ski-jumping imitation jumps
JOINT ANGULAR POSITIONS THAT INFLUENCE VOLLEYBALL ATTACK HEIGHT IN MEN’S PLAYERS
Get PDFThe aim of this study was to identify the angular position differences between high (HP) and low (LP) men’s volleyball performers at the instant of take-off and ball impact. Ten skilled collegiate men’s volleyball players were recruited from the university club team. All joint angular positions were obtained via 3D motion analysis. Results indicated that the HP players had greater normalized CoM (p \u3c 0.004) and reach height (p \u3c 0.004) at the instant of take-off and ball impact than the LP players, respectively. At the instant of take-off, HP players had a greater extension at hips, right knee, right elbow, left shoulder (flexion), and right shoulder (abduction) than LP players (p \u3c 0.004). At the instant of ball impact, the HP players demonstrated greater right elbow extension, right ankle plantar flexion, right shoulder abduction, and smaller left shoulder flexion than the LP players (p \u3c 0.004)
RELATIONSHIP OF MAXIMAL LEG STRENGTH AND SPRINTER\u27S STRIDE LENGTH
Get PDFRelationships between maximal squat strength, peak velocities, and relative stride lengths were examined in male and female collegiate sprinters during a 60m sprint. Runners were videotaped at 120 Hz. and stride lengths, and peak velocities were calculated using the Ariel APAS software. Sprinters’ 1-RM squat strengths and leg lengths were measured. A high correlation of r=.904, (p=.09) was found between the male sprinters’ leg strength and relative stride length, and the females had a low non-significant r=.515. A high significant correlational relationship of r=.988 (p=.04) was found for male leg strength and sprint velocity, and the females had a non-significant correlation r=.074. Male sprinter leg strength was a significant training factor influencing relative stride length, and sprinting velocity. While female leg strength was a not a factor for the relative stride length, and peak velocity
VALIDATION OF TWO MOBILE APPS TO PREDICT MAXIMAL STRENGTH
Get PDFThrough recent advances in smartphone technology, two mobile applications (apps), LizaPlus and PowerLift, have been developed to monitor strength training and predict 1RM based on maximal concentric velocity during submaximal exercises. The aim of this study was to assess the validity of the two apps to predict 1RM using the bench press exercise. Strong correlations were found between actual 1RM and predicted 1RM values (r-values: 0.80 to 0.86, p \u3c 0.001). Bland and Altman plots show a systematic bias such that predicted 1RMs tend to be higher than actual 1RM for both apps. Results indicate both apps are valid in predicting 1RM but there appears to be systematic bias to overestimate actual 1RM. Caution should be used when basing training loads on these predicted 1RM values as there is an increased risk of injury through prescription of excessive training load