Figure 1. Schematic representation of the tethered-swimming apparatus. By means of a
dynamometer, the tension applied to the elastic rope was constantly monitored on the
display. Continuous vocal feedback was provided by the researcher who checked the
dynamometer to an assistant who moved a pole with a coloured signal fixed at the
extremity and immersed in the water forward or backward. The tested swimmer was
instructed to follow the signal so that the assistant could adjust the tension applied to the
rope simply by moving the pole forward or backward.