Active and passive drag: the role of trunk incline

he aim of this study was to investigate the role of trunk incline (TI) and projected frontal area (A (eff)) in determining drag during active/passive measurements. Active drag (D (a)) was measured in competitive swimmers at speeds from 0.6 to 1.4 m s(-1); speed specific drag (D (a)/v (2) ) was found to decrease as a function of v (P < 0.001) to indicate that the human body becomes more streamlined with increasing speed. Indeed, both A (eff) and TI were found to decrease with v (P < 0.001) whereas C (d) (the drag coefficient) was found to be unaffected by v. These data suggest that speed specific drag depend essentially on A (eff). Additional data indicate that A (eff) is larger during front crawl swimming than during passive towing (0.4 vs. 0.24 m(2)). This suggest that D (a)/v (2) is larger than D (p)/v (2) and, at a given speed, that D (a) is larger than D (p).