ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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VARIABILITY AND THE CONTROL OF ROTATION DURING SPRINGBOARD DIVING
Get PDFThis 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 \u27kick out\u27 to affect water-entry
STATIC STRETCHING DOES NOT AFFECT MEASURES OF POWER AND FATIGUE DURING VIGOROUS CYCLING AMONG WOMEN
Get PDFStatic stretching has been linked to lesser performance in many sport activities. The purpose of this study was to determine the impact of static stretching upon power and fatigue performance measures during vigorous cycling. In this study, vigorous cycling was assessed using the Wingate Anaerobic Test (WAnT). Using a counterbalanced design, twenty nine female participants completed standardized static stretching and nonstretching protocols prior to completing the WAnT. No statistically-significant differences (p = 0.05) were found between conditions for measures of peak power (PP), low power (LP) or fatigue index (FI). These findings suggest that static stretching had no statistically-significant effect on these performance measures commonly assessed during the WAnT
A CLINICAL PERSPECTIVE OF POSITIONING FOR THE ENDURANCE BICYCLIST
Get PDFOptimal fitting of the endurance bicyclist to the bicycle is vital for improving performance, increasing control, avoiding overuse injuries, and promoting comfort. Neutral position of the bicyclist as well as static and dynamic fitting for the road and off-road bicyclist is important. Musculoskeletal screening procedures of the bicyclist are also important and emphasis will be placed on prevention and intervention of two common overuse injuries: anterior knee pain and lower back pain. Comparisons of bicycle fit and overuse injuries for the off-road bicyclist and racer will also be introduced
ANALYSIS OF MUSCLE FORCES DURING DOWNHILL WALKING
Get PDFThe aim of this study was to analyse gait parameters and to quantify lower extremity muscles forces in downhill walking at different inclinations. Ten healthy male subjects walked at self-paced and at constant pre-set speed of 4 km/h on a ramp at different inclinations of -18°, -12°, -6° and 0°. Muscle forces were analysed by a musculoskeletal model (AnyBody) and were divided in four groups: quadriceps, hamstrings, calf muscles and shin muscles. Results showed significant increases in quadriceps and decreases in calf muscle forces with increasing inclination. Furthermore, quadriceps muscle forces were affected by walking speed. Hamstrings, quadriceps and calf muscle forces can be correlated with hip, knee and ankle joint moments, respectively. Therefore, it can be concluded that forces of major muscle groups can explain the joint extension moments
ASSESSMENT OF MUSCLE ACTIVATION RATIONS DURING LOWER EXTREMITY RESISTANCE EXERCISES
Get PDFThe purpose of this study was to examine muscular activation ratios during lower extremity resistance training exercises. The literature implicates muscular activation ratios, such as quadricep-hamstring and insufficient semitendonosis activation as possible factors regarding ACL injuries. Twenty one subjects performed a series of 6 exercises. EMG activity was measured in the following muscles: Rectus femoris, vastus lateralis, vastus medialis, biceps femoris and semitendinosis. Data indicate that most of those exercises show favorable quadricep-hamsrting ratios and most of them also showed favorable medial-lateral hamstring ratios.It is possible that performing exercises that target the muscles that help against injury or produce favorable activation ratios could also help us avoid injuries in sports situations
A SIMPLE OUTLIER DETECTION METHOD FOR INTRA-SUBJECT TIME-SERIES DATA
Get PDFRemoval of outliers assists in improving the statistical representations of the general finding. Currently no simple method is advocated for detecting outliers in time-series data obtained in biomechanics. The aim was to demonstrate a 2-stage method for detecting outliers. The test data were the ankle and knee angles for the strides (n=41±2.8) from treadmill running (n=6). Stage 1 was an outlier detection of >±3.3SD from the mean at each time-point, and removing any stride with an outlier. Stage 2, with padding of k=3 points and mean-detrending, was a moving window SD for all strides across ±k data points, and removing strides with any point >±2.58SD. After removal of 5.2±3 (stage 1) and 2.0±1.4 (stage 2) strides, the mean was unchanged and the SD reduced (
THE RELATIONSHIP OF FORCE PRODUCTION ASYMMETRY AND PERFORMANCE IN ATHLETES OF DIFFERENT STRENGTH LEVELS
Get PDFThe purpose of this study was to evaluate the relationship between force production asymmetry and performance of athletes with differing strength levels in males and females. Collegiate athletes (n=129) from various sports were ranked according to isometric mid-thigh pull peak force and the top (‘strong’) and bottom (‘weak’) 25% were used for analysis. Symmetry index (SI) scores were calculated and correlated with their respective force-time characteristics using bivariate correlations. For the weaker males, several negative moderate correlations were observed; however, no statistically significant correlations were observed for the females in either group. These findings indicate that force production asymmetry is inversely related to performance in weaker male athletes during isometric strength testing; however, similar to previous findings, this relationship is not apparent in stronger males
HIGH-LOADING ABSORPTION CHARACTERISTICS OF NATURAL AND ARTIFICIAL TURFS
Get PDFThe present study was designed to illustrate shock attenuation characteristics of natural turf as a target property for long pile artificial turf (3-g turf) and to compare the property with that of existing 3-g turf systems. A recently proposed new high loading test was conducted to detect the initial state of shock attenuation property of natural turfs with two different bases (sod and sand base) and of 3-g turfs with three different infills (sand, rubber and sand/rubber). Clear differences between these turfs were observed as the natural turfs are having a higher impact damping and a larger hysteresis with plastic surface deformation. Those features would be beneficial in lowering a high load imparted to the human body but might limit player’s performance
COMPARISON OF KINEMATICS AND ACCURACY OF OVERHAND AMERICAN FOOTBALL THROWING
Get PDFThis study examined elbow angle, wrist velocity and throwing accuracy during American Football throws. Six repetitions of three types of throws: Self-selected pass (SS), Lob pass (L), and a Bullet pass (B); were performed to hit a point scaled target from 10.97 m. Independent variables were frontal plane shoulder angle (more or less than 90º) and throw type; dependent variables were elbow angle in the sagittal plane, wrist velocity at ball release, and accuracy. There were no differences for shoulder angle for any variable; while throw types differed only for wrist speed (highest to lowest B, SS, and L). Significant interactions occurred for all variables. These findings suggest that recommendations for American football throwing technique are complicated by the combination of throw type and shoulder angle; and that with no restrictions subjects will throw with more accuracy
MEASUREMENT OF PEAK FORCE EXPERIENCED BY MALES DURING ASSISTED AND UNASSISTED PULL-UPS
Get PDFThe purpose of this study was to measure the peak force (PF) generated by males while performing assisted pull-ups (APU) and unassisted pull-ups (UPU) with pronated (PUP) and supinated (SUP) hand grips. Twenty-five men (mean ± SD: age= 23 ± 3 y; height= 180 ± 6 cm; weight= 88 ± 14 kg, APU: N=12, UPU: N=13) participated. Participants performed 2 sets of 10 pull-ups (PU) (1 PUP, 1 SUP) in randomized order on a PU bar attached to a force plate. PF generated during each PU was normalized to body weight (BW). There was no significant difference in PF generated between grips (P = 0.158) but there were significant differences in the PF generated over the course of 10 repetitions (