VALIDITY OF ESTIMATING ACTIVE DRAG USING THE BOTH ASSISTED AND RESISTED TECHNIQUES WITH FLUCTUATING VELOCITY

The main purpose of this study was to examine the validity of assisted and resisted techniques which are used for active drag estimation. Ten national and international male sprint swimmers performed two maximum effort free swims, two passive trials and two active drag trials in each technique. The computation of active drag for both techniques was based upon assumptions of the Velocity Perturbation Method (VPM) of Kolmogorov and Duplishcheva (1992). Results of a one-way ANOVA with repeated measures indicated there was no statistical significance between the active drag values obtained from the assisted and resisted techniques (p=0.05). There was however variation between active drag values. This is likely due to different power outputs that were applied during the test conditions and also, active drag varies as a function velocity squared

RELIABILITY OF ESTIMATING ACTIVE DRAG USING THE ASSISTED TOWING METHOD (ATM) WITH FLUCTUATING VELOCITY

The aim of this study was to examine the reliability of active drag values obtained using a method that compared free swim velocity with measurements taken by towing swimmers slightly faster than their maximum swim speed, while allowing for intra stroke velocity fluctuations. Using nine national level swimmers on two alternate days, reliability was determined using within-subject intra-class correlation coefficients (ICC) within each day and between the days. The ICCs for days one and two were 0.80 and 0.84 respectively, while the comparison of mean active drag values between days was 0.92. Results found that the ATM method with fluctuating velocity to be only moderately reliable within a single test. Taking average values improved this reliability, even when measured over different days. Further investigation is suggested to improve the current method

CORRELATIONS BETWEEN TRUNK AND BAT KINEMATICS FOR BASEBALL PLAYERS CALCULATED USING BOTH INDIVIDUAL AND GROUP STATISTICS

This study aimed to investigate kinematic parameters associated with high batting velocity by using both group and individual analysis methods. Twenty seven junior baseball players each performed 35 strikes off a tee at speeds of 60, 80 and 100% of maximum; with pelvis, upper-trunk and bat kinematics measured by 3D motion analysis. The maximum values of all kinematic variables were positively associated with bat speed when assessed with both group and individual methods. For variables measured at impact, however, there were very different individual associations; with some participants showing strong positive correlations and others having similarly strong negative correlations with bat speed. These findings indicate that different players use different techniques to achieve high bat speeds

THE KINEMATIC DIFFERENCES BETWEEN THE LEG-SPIN AND OFFSPIN BOWLING TECHNIQUES IN CRICKET

The purpose of this paper was to determine kinematic differences between the off-spin and leg-spin bowling techniques in cricket. The two techniques are often coached similarly; however, a comparative biomechanical analysis of leg-spin and off-spin bowling has not been performed. A 3D Cortex motion analysis system was used to track 52 markers strategically placed on all the major segments of 23 off-spin and 15 leg-spin bowlers of district level. It was found that the two techniques varied in terms of stride length, but other variables which were not previously differentiated in coaching manuals also displayed significant difference. These results highlight potential technique points that will be of benefit when coaching bowlers of each spin direction

A KINEMATIC ANALYSIS OF THE BACKWARD 2.5 SOMERSAULTS WITH 1.5 TWISTS DIVE (5253B) FROM THE 3M SPRINGBOARD

The aim of this case study was to determine the practical application of 3D inertial measurement units and compare angular velocity profiles, key position angles and event timings for the backward 2½ somersaults with 1½ twists (5253B). One male diver performed 11 trials of the 5253B while 3D inertial measurement units (IMU) and high speed video were used to measure kinematic variables. Peak angular velocity about the somersault and twist axes were 900±11deg/s and -1435±28.deg/s, with highly consistent patterns displayed for total flight time

CHANGES IN STROKE KINEMATICS DURING RESISTED AND ASSISTED FREESTYLE SWIMMING

Ten subjects swam 50m freestyle trials using; resisted (RS), assisted (AS), and free swimming (FS). Data from 2 underwater cameras were combined to provide a 3-D reconstruction of each trial. During RS, the stroke length (SL), mean 3D resultant hand velocity and average forward velocity (AV) significantly (p < 0.05) decreased compared to the FS trial. During RS, the swimmers were unable to generate enough force to prevent the tether from slowing them down. Further, calculations suggest that the average propulsive force acting on the swimmer was not increased during RS. During the AS trial SL, stroke rate and AV increased, while maximum hand depth decreased relative to the FS trial. There appear to be some positive benefits, however the technique changes found during both RS and AS result in these forms of training remaining questionable

VARIABILITY AND THE CONTROL OF ROTATION DURING SPRINGBOARD DIVING

This study explored the variability in angular velocity profiles across multiple somersault dives. Four international level divers performed 4-6 repeated dives of either 3½ somersaults with pike, or 4½ with tuck, from a 3 m springboard. An inertial measurement unit (IMU) was attached to the lower back to record angular velocity during all trials. Each diver produced highly consistent patterns of dive time duration and angular velocity, with standard deviations less than 1% of the mean. No consistent pattern of correlation between velocity and duration of the held tuck/pike position was apparent, and no other evidence of mid-dive feedback control was evident from the present methodology. This may be the result of performing dives with a high degree of difficulty, providing little time for movement adjustments during 'kick out' to affect water-entry

Comment on “Effects of Arsenite during Fetal Development on Energy Metabolism and Susceptibility to Diet-Induced Fatty Liver Diseases in Male Mice” and “Mechanisms Underlying Latent Disease Risk Associated with Early-Life Arsenic Exposure: Current Trends and Scientific Gaps”

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