The determination of drag in front crawl swimming

H.M. Toussaint, P.E. Roos, S. Kolmogorov

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    The measurement of drag while swimming (i.e. active drag) is a controversial issue. Therefore, in a group of six elite swimmers two active drag measurement methods were compared to assess whether both measure the same retarding force during swimming. In method 1 push-off forces are measured directly using the system to measure active drag (MAD-system). In method 2 (the velocity perturbation method, VPM) drag is estimated from the difference in swimming speed when subjects swim twice at maximal effort (assuming equal power output and assuming a quadratic drag-speed relationship): once swimming free, and once swimming with a hydrodynamic body attached that created a known additional resistance. The average drag for the VPM tests (53.2N) was statistically significant and different from the active drag for the MAD-test (66.9N), paired Student's t-test: 2.484, 12 DF, p=0.029. A post hoc analysis was performed to assess whether the two methods measure a different phenomenon. Based on the drag speed curve obtained with the MAD-system, the VPM-data were re-examined. For diverging drag determinations the assumption of equal power output of the 'free' trial (swimming free) vs. the towing trial (swimming with hydrodynamic buoy) appeared to be violated. The regression of the relative difference in force (MAD vs. VPM) on the relative difference in power (swimming free vs. swimming with hydrodynamic body) was: %Δdrag=1. 898×%Δpower -4.498, r
    Original languageEnglish
    Pages (from-to)1655-1663
    JournalJournal of Biomechanics
    Volume37
    DOIs
    Publication statusPublished - 2004

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