Passive and active drag coefficients of the four conventional swimming techniques

Accepting the importance of the hydrodynamic profile in competitive swimming, we aimed to characterize (and compare) the active and passive drag coefficients of the four conventional swimming techniques for male and female swimmers, as well as to relate these variables with performance. Ten competitive swimmers (four males and six females of 14-20 years of age) had their passive drag estimated from the underwater gliding velocity/time curve and the active drag assessed using the velocity perturbation method. For obtaining passive and active drag coefficients swimmers cross sectional area was assessed through planimetry and body volume to the power 2/3. We observed that: (a) front crawl and backstroke active drag coefficients were higher in male than females (~0.35-0.45 vs. 0.25-0.30); (b) passive drag coefficients did not differ between genders (~0.40); (c) front crawl and butterfly active drag coefficients were lower than passive drag values for the total sample; (d) different techniques active drag coefficients did not relate with swimming performance (r = [-.59-.58], p > .05); and (e) backstroke passive drag coefficient relate directly with performance (r = .81, p .05) but this behaviour was not observed for the remaining techniques. Active and passive drag coefficients should not be interpreted alone but related with differences in body form and composition, and technical proficiency.