In swimming not all of the total mechanical power (P") generated by the swimmer is available to overcome drag. The propulsive efficiency (ep) is defined as the ratio of power to overcome drag (Pd) relative total mechanical power. The System to Measure Active Drag provides fixed push of pads below the water enabling propulsion generation without loss of energy to the water. Therefore, all-out sprints performed on the M.A.D.-system enabled faster swimming than all-out sprints swimming free. Assuming that Pd relates to swimming speed cubed (v3) and assuming equal power Output in two 25 m sprints (free and MAD), the ratio of v3 sprinting all-out 'free' relative to v3 on the M.A.D.-System reflects ep. For 13 elite swimmers ep of 75% (range 68 - 84%) for v = 1.64 m*s-1 were found. The determination of ep based on sprints free and on the M.A.D. System, is fast and is used to evaluate changes in performance with training.
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