Drag, Power and Velocity

The study of swimming has long centered upon the two fundamental determinants of swimming speed: the resistive forces experienced by the swimmer and the propulsive forces that the swimmer can generate.  While much research has attempted to identify the factors that affect these two determinants, the limitations of measurement have prevented conclusive statements about propulsive and resistive forces in swimming.  Difficulties in measurement stem from three main sources.

First, measurements of the force and power generated while swimming are difficult to obtain due to the inability to quantify force exerted on a fluid.  Second, separating the resistive forces from the propulsive forces is challenging because at constant velocity they are inherently equal and opposite.  The final difficulty is that the resistive force varies with velocity.  Thus comparison of resistive forces must always involve consideration of the velocity at which they are measured.