Down with Retirement: Implications of Embodied Cognition for Healthy Aging

Action Contro

SWIM START STANDPOINTS ON THE OSB11 STARTING BLOCK

Systematic variations of the preferred stance positions of 17 elite swimmers on the OSB11 were analyzed in regard to block time, swim start times to 5 m, horizontal take-off velocities, and horizontal vs. vertical peak force values. The variations encompassed changes of the front leg (left vs. right), the centre of mass (CM) height (low vs. high), the stance width (narrow vs. wide), and a rear vs. a front weighted stance. For half of the subjects, at least one stance alter-native provided a better swim start time than the preferred stance with an average gain of 0,06s and extreme improvements of up to 0,14s. The majority of the improvements were associated with a change to the front weighted stance, a narrow foot displacement, and an elevated CM position

A BIOMECHANICAL EVALUATION OF DIVE START PERFORMANCE IN SWIMMING-FORCE DEVElOPMENT CHARACTERISTICS AND ANGULAR MOMENTUM

Dive start performance has been considered a major determinant for race swimming over short distances (e.g. Lyttle & Benjanuvatra at www.coachesinfo.com).This performance is based on chronologically interrelated sub components such as take-off performance on the block, flight performance before water contact, dive entry while immersing into the water, and gliding performance before the first swim stroke. In this "work in progress" report, we will focus on the take-off performance from the block. We will introduce a portable 2D-force measurement starting block which can be installed in different training centres and pool locations. Selected data on a research program for the biomechanical evaluation of dive start performance in swimming will be presented in order to show force development profiles from junior level swimmers. In addition, we will introduce data on the angular momentum at take-off. We will discuss some validation procedures in order to estimate the quality of the underlying calculations. To date, angular momentum has hardly been evaluated in biomechanical studies on the dive start in swimming. Nevertheless, angular momentum might play a crucial role for the angle of dive entry

INFLUENCES OF BODY CONFIGURATION ON THE BIOMECHANICAL PROPERTIES

The purpose of this study was to investigate the influences of body configuration on the biomechanical properties of leg extensor muscles in squat jump (SJ) performances. Ground reaction force data were collected during four different SJ tests of SJ70, SJ90, SJ110, and SJ130 (numbers denoted the knee angles) for maximum jump execution of 22 subjects. The results showed that the forces measured on a force platform, and other variables calculated from the force-time data, were strongly associated with the body configuration at push-off. Peak and average forces were greater in wider knee angle conditions, however, optimum power output and jumping height appeared in SJ90. From the data obtained in this study, it seemed that the force production measured with SJ test could not be used simply to assess the level of active state and muscular strength of leg extensors. The reaction force measured on a platform was the vertical component of the muscular strength generated by extensors, which was determined not only by the strength level, but also the joint angles at push-off position

PERFORMANCE GAINS IN RELAY SWIMMING (PART I): THE RELAY START BENEFIT COMPONENT

The present study aimed to detect statistical differences in the start performance between relay and individual races accounting for gender and relay start techniques. Race data of relay races and corresponding individual races from European Championships (2019) were analysed. Linear mixed models for repeated measures were applied to compare the differences in the 15 m start times (after toe-off) between relay and individual races accounting for gender and relay start techniques. The results revealed a small time benefit for step-starts over no-step starts in the freestyle races. Furthermore, depending on techniques, male butterfly swimmers showed more pronounced differences in their start performance as compared to female swimmers. However, no statistical differences were found in breaststroke races for either gender or relay start technique. The findings of the present study may improve coaches\u27 and swimmers\u27 understanding of the downsides and benefits of different relay starts. Based on results, we suggest that, at least for freestyle relays, a step-start should be the relay start technique of choice

TENNIS GROUND STROKES FROM A BIRD’S EYE VIEW - A ESTIMATE OF ANGULAR MOMENTUM ABOUT THE LONGITUDINAL BODY AXIS

In this paper, a simple 2D video method will be outlined to estimate the angular momentum about the longitudinal body axis in tennis ground strokes from the base line. From a bird’s eye view, ground strokes of 19 young male experienced tennis players with two different skill levels were analyzed when returning balls released from a ball machine with three different ball frequencies. The angle between the shoulder axis and the base line was used as an estimate for the angular momentum about the longitudinal body axis. A validation procedure with a fully automated 3D motion capture system as adopted to evaluate the error involved in the 2D motion analysis. The results of this study show that for forehand and backhand strokes advanced young tennis players show consistently larger shoulder-baseline angles across all ball frequencies than players with a lower skill level

KINEMATIC STRATEGIES TO KEEP AN UNCHANGED MARGIN OF STABILITY DURING TREADMILL RUNNING ON AN EVEN AND UNEVEN SURFACE

Understanding how to control stability when running, particularly when being exposed to uneven terrain, is vital to prevent falls and to get an insight into compensatory strategies while running on uneven terrain. The purpose of this study was to assess surface related differences of the margin of stability, kinematics of hip and knee and upper body acceleration which may affect the control of running stability. Eighteen healthy younger adults ran on an even and an uneven surfaced treadmill for two minutes at fixed speeds of 2.0 m/s (female) and 2.2 m/s (male), respectively. Results showed an unchanged margin of stability in both conditions. Further, lower limb kinematics, step width variability and upper body acceleration increased on the uneven surface meaningfully to keep the extrapolated centre of mass within the base of support

Bewegungspriming

Le mouvement comme mode de réaction alternatif et implicite en jeu et dans les sports d'opposition, aux représentations visuelles quand celles ci ne sont pas suffisante

Different strength declines in leg primary movers versus stabilizers across age-Implications for the risk of falls in older adults?

This study investigated differences in the declines of isometric strength in hip abductors and adductors versus knee extensors across four different age groups (n = 31: 11.2 ± 1.0 y, n = 30: 23.1 ± 2.7 y, n = 27: 48.9 ± 4.4 y, and n = 33: 70.1 ± 4.2 y) with a total of 121 female subjects. As a starting point, we assumed that, during their daily activities, elderly people would use their leg stabilizers less frequently than their leg primary movers as compared to younger people. Given that muscle strength decreases in the course of the aging process, we hypothesized that larger strength declines in hip abductors and hip adductors as compared to knee extensors would be detected across age. Maximal isometric force for these muscle groups was assessed with a digital hand-held dynamometer. Measurements were taken at 75% of the thigh or shank length and expressed relative to body weight and lever arm length. Intratester reliability of the normalized maximal torques was estimated by using Cronbach's alpha and calculated to be larger than 0.95. The obtained results indicate a clearly more pronounced strength decline in hip abductors and hip adductors across age than in the knee extensors. Therefore, a particular need for strength training of the lower extremity stabilizer muscles during the aging process is implied