The Strokes Simplified VI- Underwater Kicking
As with all strokes, great dolphin kicking is the result of the same principles for fast swimming- increased propulsion, reduced resistance, and great rhythm. The major components of successful dolphin kicking include-
Maintain a Stable Platform
Create as Much Propulsion as Possible
Maintain Equal Propulsion and Tempo in Both Directions
Maintain a Posture that Reduces Drag
These four components all interact to some extent and any problems with timing will influence the execution of any action. There are other aspects of the stroke that can be considered; however, these aspects are usually errors that are preventing swimmers from accomplishing the critical tasks. Other aspects of technique can be important, but only in the context of the effect each action has on the four priorities listed above. If a movement is not negatively affecting the main priorities, it’s best left alone.
Maintain a Stable Platform
To effectively undulate, swimmers must establish a stable platform at the top of the body. Once this platform exists, effective undulation and a transfer of force down through the body can exist. This allows for swimmers to harness the power of undulation as opposed to relying exclusively on the strength of the legs. Swimmers with excessive action of the arms and head will struggle to find the stability required to create power through the legs.
While the platform originates in the upper chest and arms, different swimmers have different degrees of rigidity in their platform. Some ae incredibly stable, while others undulate slightly.
Create as Much Propulsion as Possible
Effective propulsive starts from a point of stability which allows for force transfer to the legs. It is here that force is actually transmitted to the water through the shins and feet. Swimmers must focus on maintaining effective propelling surfaces, or holding water, for as long as possible. In addition, they should strive to create as much pressure on the shins and feet as possible in both directions. A critical aspect of maximizing propulsion is kicking all the way through the center line.
Maintain Equal Propulsion and Tempo in Both Directions
While the anatomy of the human leg is not conducive to truly symmetrical dolphin kicking, elite dolphin kickers are much more effective at creating propulsion in both directions. Beyond the potential to create propulsion independently, the backward kick pays a crucial role in facilitating the effectiveness of the forward kick. The backward kick moves a volume water which can then be kicked against by the forward kick. The more water that is moved backward, the ‘thicker’ the water will be during the subsequent forward kick.
An effective backward kick will tend to be straighter during the recovery until the end where the knee bends. This action creates the potential for a whip-like reversal during the down kick. For most swimmers, this backward will feel very stiff.
In addition, elite kickers maintain higher foot speed while kicking back behind the body. High velocity reversal of the kicking action may facilitate the creation of propulsive vortices. To take advantage of these effects, swimmers need to makes sure foot speed is high in both directions. As quick note, foot speed is not synonymous with kick frequency. Foot speed is how fast the feet are moving, whereas kick frequency is how long it takes to complete a full kicking action. Swimmers with a high foot speed and large amplitude of the feet will be able to create high foot speed without rushing the kicks.
Maintain a Posture that Reduces Drag
Undulation is critical for creating propulsion. At the same time, increases in undulation will distort streamline and increase drag. Swimmers should strive to use the amount of undulation that allows the maximization of propulsion while minimizing drag.
Independent of undulation, maintaining spinal alignment is also required to minimize drag. Moving through the water with an arched spine will unnecessarily increase drag, even if undulation in minimized. Further, an arched spine will also prevent swimmers from fully kicking through the center line.