Abstract

The swimming speed is equal to the product of the propelling efficiency and the energy per time unit delivered by the swimmer, divided by the drag force. In this paper, only the drag force is discussed. The mean drag force equals the mean propulsive force at constant swimming speed. The latter is measured by the so-called MAD-system: a 23 m. tube at 0.8 m under the water surface, on which grips are attached. The swimmer pushes off against these grips in a front crawl like swimming movement. At the end of the tube, a force transducer is fixed, which yields the propulsive and thus the drag force during swimming. The magnitude is found to be equal to the so-called passive drag values, obtained by towing the swimmer through the water. Individual values of the drag force are dependent on body built, body position in the water and speed. It is found that the drag force is not related to the maximal swimming performance. Apparently, propelling efficiency and/or energy production during swimming are more discriminative factors. It is suggested, that the MAD-system is a suitable training device: during a frontcrawl like swimming exercise, some overload concerning the propulsive force is required, at almost the same arm movement frequency and with a similar arm muscle use as during normal swimming. Verf.-Referat