Original Article

European Journal of Applied Physiology

, Volume 94, Issue 1, pp 134-144

First online:

An energy balance of front crawl

  • P. ZamparoAffiliated withDipartimento di Scienze e Tecnologie Biomediche, Università degli Studi di Udine Email author 
  • , D. R. PendergastAffiliated withDepartment of Physiology, University at Buffalo
  • , J. MollendorfAffiliated withDepartment of Mechanical Engineering, University at Buffalo
  • , A. TerminAffiliated withDepartment of Athletics, University at Buffalo
  • , A. E. MinettiAffiliated withInstitute of Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University

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Abstract

With the aim of computing a complete energy balance of front crawl, the energy cost per unit distance (C= Ėv−1, where Ė is the metabolic power and v is the speed) and the overall efficiency (ηo=Wtot/C, where Wtot is the mechanical work per unit distance) were calculated for subjects swimming with and without fins. In aquatic locomotion Wtot is given by the sum of: (1) Wint, the internal work, which was calculated from video analysis, (2) Wd, the work to overcome hydrodynamic resistance, which was calculated from measures of active drag, and (3) Wk, calculated from measures of Froude efficiency (ηF). In turn, ηF=Wd/(Wd+Wk) and was calculated by modelling the arm movement as that of a paddle wheel. When swimming at speeds from 1.0 to 1.4 m s−1, ηF is about 0.5, power to overcome water resistance (active body drag × v) and power to give water kinetic energy increase from 50 to 100 W, and internal mechanical power from 10 to 30 W. In the same range of speeds Ė increases from 600 to 1,200 W and C from 600 to 800 J m−1. The use of fins decreases total mechanical power and C by the same amount (10–15%) so that ηo (overall efficiency) is the same when swimming with or without fins [0.20 (0.03)]. The values of ηo are higher than previously reported for the front crawl, essentially because of the larger values of Wtot calculated in this study. This is so because the contribution of Wint to Wtot was taken into account, and because ηF was computed by also taking into account the contribution of the legs to forward propulsion.

Keywords

Swimming Biomechanics Energetics Propelling efficiency Fins