Added mass in human swimmers: Age and gender differences

Abstract

This file was dowloaded from the institutional repository Brage NIH -brage.bibsys.no/nih Caspersen, C., Berthelsen, A., Eik, M., Pakozdi, C., Kjendlie, P.-L. (2010).Added mass in human swimmers: age and gender differences. Title: Added mass in human swimmers: age and gender differences. AbstractIn unstationary swimming (changing velocity), some of the water around the swimmer is set in motion. This can be thought of as an added mass (Ma) of water. The purpose of this study was to find added mass on human swimmers and investigate the effect of shape and body size. Thirty subjects were connected to a 2.8m long bar with handles, attached with springs (stiffness k=318N/m) and a force cell. By oscillating this system vertically and registering the period of oscillations it was possible to find the added mass of the swimmer, given the known masses of the bar and swimmer.Relative added mass (Ma%) for boys, women and men were, respectively, 26.8±2.9%, 23.6±1.6% and 26.8±2.3% of the subjects total mass. This study reported significantly lower added mass (p<0.001) and relative added mass (p<0.002) for women compared to men, which indicate that the possible body shape differences between genders may be an important factor determining added mass. Boys had significantly lower (p<0.001) added mass than men. When added mass was scaled for body size there were no significant differences (p=0.996) between boys and men, which indicated that body size is an important factor that influences added mass. The added mass in this study seems to be lower and within a smaller range than previously reported (Klauck, 1999;Eik et al., 2008). It is concluded that the added mass in human swimmers, in extended gliding position are approximately ¼ of the subjects' body mass.

Added masses computation for unconventional airships and aerostats through geometric shape evaluation and meshing

“…The potentials α � cos�n, x�� β � cos�n, y� � γ � cos�n, z� (17) in order to write the watertight condition as:…”

“…[2], but the estimation is inaccurate for the complex and irregular shapes typical of modern unconventional airships, although it can be considered a way to provide preliminary added masses estimates. Another approach to added masses computation is by performing experimental tests; this has been applied, for instance, to swimmers [17]. Other authors like Refs.…”

Characterization of speed fluctuation and drag force in young swimmers: A gender comparison

“…Moreover, any estimation has a small to large bias. In this sense, it was decided not to estimate the projected surface area but to actually measure it with a photometric technique popularized in the recent years (Caspersen et al, 2010;Nicolas & Bideau, 2009;Nicolas, Bideau, Colobert, & Berton, 2007;Vilas-Boas et al, 2010). To the best of our knowledge, there is no study regarding dv in children.…”

“…For the S measurement, swimmers were photographed with a digital camera (DSC-T7, Sony, Tokyo, Japan) in the transverse plane from above (Caspersen, Berthelsen, Eik, Pâkozdi, & Kjendlie, 2010). Subjects were on land, in the upright and hydrodynamic position.…”

“…where D p represents the swimmer's passive drag, BM the swimmers body mass, m a the swimmer's added water mass, estimated as being approximately 28% for subject with similar age (Caspersen et al, 2010), and a the swimmer's acceleration. Passive drag coefficient (C Dp ) was calculated as:…”