Study protocol for the feedback and the natural learning group.

<p>Pre- and posttest consisted of 4 x 3min blocks each. Seven practice sessions consisted of 2 x 4min each. A different propulsion variable at each practice session was presented in the form of real-time visual feedback to the participants in the feedback group. The order of the propulsion variables was counterbalanced over the participants. Participants in the natural learning group practiced without feedback. Last minute of each exercise block was used in the analysis.