title: Planimetric frontal area in the four swimming strokes: implications for drag, energetics and speed.
abstract: The purpose of this study was to use the planimetric method to determine frontal area (Ap) throughout the stroke cycle in the four swimming strokes as well as during "streamlined leg kicking". The minimum Ap values in all strokes are similar to those assessed during "streamlined leg kicking" (about 0.13m(2)). Active drag (Da=1/2ρ Cd Ap v(2)) was then calculated/estimated based on the average Ap values, as calculated for a full cycle in each condition. Da is the lowest in the "streamlined leg kicking" condition (Da=19.5v(2), e.g., similar to the values of passive drag reported in the literature), is similar in front crawl (Da=30.0v(2)), backstroke (Da=26.9v(2)) and butterfly (Da=28.5v(2)) and is the largest in the breaststroke (Da=37.5v(2)). Based on the C vs. v relationships reported in the literature for the four strokes it is then possible to estimate drag efficiency: for a speed of 1.5ms(-1), it ranges from 0.035-0.038 (breaststroke and backstroke, respectively) to 0.052-0.058 (butterfly and front crawl, respectively). This study is the first to establish Ap values throughout the swimming cycle for all swimming strokes and these findings have implications for active drag estimates, for the energetics of swimming and for swimming speed.
authors.affiliation: Department for Life Quality Studies, Rimini Campus, University of Bologna, Bologna, Italy. Electronic address: giorgio.gatta@unibo.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Gatta
authors.affiliation: Department for Life Quality Studies, Rimini Campus, University of Bologna, Bologna, Italy. Electronic address: m.cortesi@unibo.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Cortesi
authors.affiliation: Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Bologna, Italy. Electronic address: silvia.fantozzi@unibo.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fantozzi
authors.affiliation: Department of Neurological and Movement Sciences, University of Verona, Verona, Italy. Electronic address: paola.zamparo@univr.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Zamparo
mesh_terms: D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional; D008297:Male; D009068:Movement; D013550:Swimming / Q000502:physiology*; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water
keywords: Frontal area; Hydrodinamic resistence; Planimetric method; Swimming