Determination of the Drag Coefficient during the First and Second Gliding Positions of the Breaststroke Underwater Stroke

in Journal of Applied Biomechanics
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The purpose of the current study was to assess and to compare the hydrodynamics of the first and second gliding positions of the breaststroke underwater stroke used after starts and turns, considering drag force (D), drag coefficient (CD) and cross-sectional area (S). Twelve national-level swimmers were tested (6 males and 6 females, respectively 18.2 ± 4.0 and 17.3 ± 3.0 years old). Hydrodynamic parameters were assessed through inverse dynamics from the velocity to time curve characteristic of the underwater armstroke of the breaststroke technique. The results allow us to conclude that, for the same gliding velocities (1.37 ± 0.124 m/s), D and the swimmers’ S and CD values obtained for the first gliding position are significantly lower than the corresponding values obtained for the second gliding position of the breaststroke underwater stroke (31.67 ± 6.44 N vs. 46.25 ± 7.22 N; 740.42 ± 101.89 cm2 vs. 784.25 ± 99.62 cm2 and 0.458 ± 0.076 vs. 0.664 ± 0.234, respectively). These differences observed for the total sample were not evident for each one of the gender’s subgroups.

João Paulo Vilas-Boas (Corresponding Author) is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal, and the Centre of Research, Education, Innovation and Intervention in Sport. Lígia Costa is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal. Ricardo J. Fernandes is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal, and the Centre of Research, Education, Innovation and Intervention in Sport. João Ribeiro is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal. Pedro Figueiredo is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal, and the Centre of Research, Education, Innovation and Intervention in Sport. Daniel Marinho is with the University of Beira Interior, Covilhã, Portugal, and the Research Center in Sports, Health and Human Development, Vila Real, Portugal. António J. Silva and Abel Rouboa are each with the Research Center in Sports, Health and Human Development, Vila Real, Portugal, and with the University of Trás-os-montes e Alto Douro, Vila Real, Portugal. Leandro Machado is with the University of Porto, Faculty of Sports, LABMEC, Porto, Portugal, and the Centre of Research, Education, Innovation and Intervention in Sport.