Abstract des Autors

When switching from 200-m to 100-m breaststroke, velocity increase is combined with frequency increase. However, unlike the other three strokes, it leads to a decrease in stroke length. The phases of a stroke cycle are not modified in the similar manner with increasing velocity. The aim of this study was to find out which phases are increasing, in relative value, after verifying that velocity increase leads to a decrease in glide time. Eleven international and national level swimmers (5 males and 6 females) swam a 20-m breaststroke distance at three increasing velocities (200, 100 and 50-m velocities). Side and front underwater views were recorded. At each stroke velocity, a picture calculator (20 ms) measured three representative cycles. Four phases: leg propulsion, glide, arm propulsion, arm and leg recovery were calculated in percentage scale. The results showed that the velocity increase was combined with significant reduction in glide time. This increase logically depends on the increase of drag components of forward movement. If extreme velocities (200 versus 50-m) lead to the increase of respective length duration of leg and arm propulsion and recovery phases, these changes are of a different kind on intermediate velocities. Verf.-Referat