Why have swimmers neglected the “fish kick” technique?

Abstract

Given that horizontal-plane undulation (“fish kicking”) just under the water surface is more effective (from a hydrodynamic point of view) than vertical-plane undulation (“dolphin kicking”) (Lighthill, 1975), why then do expert swimmers experts not use this technique after the turn and before resuming their arm stroking action? Fourteen national-level swimmers (6 males and 8 females) were timed over 15m and 25m trials while dolphin kicking and then fish kicking. A comparative analysis revealed the strong potential of fish kicking (which equates to dolphin kicking on the side). Over 25m, the fish kicking times were only slightly slower than the dolphin kicking times, and this was in the absence of prior training. Over 15m and at no more than 1 metre below the surface, the swimmers went significantly faster in the side position (p<0.05). A multifactorial analysis (MFA) revealed that the determinants of high performance while kicking underwater are relatively independent of the swimmer’s absolute speed (e.g. personal best for 50m front crawl), gender, age and weight. In contrast, in the population of swimmers studied here, being a backstroke or butterfly specialist and being short were factors that appeared to favour speed in the undulation trials.

• Swimming
• Performance
• Fish kick
• Dolphin kick
• Immersion