Tips & Advice

Improve your kick: by swim analyst Amy Bathgate

No matter what the discipline, event or reason for your swimming the legs play a vital role in increasing swimming speed and efficiency. Many of the world’s best swimmers stand out above the rest for having exceptional kicks. So what’s the big deal? And how can the kick be improved in “not-so-natural” kickers?

Firstly, let’s look at the four major functions of the legs in swimming:

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Propulsion obviously allows you to move forward, which is the ultimate goal in swimming, yet this aspect of the kick is sometimes under-appreciated within the swimming stroke. Researchers have proven the kick to positively aid propulsion in some swimmers, yet negatively affect the propulsion of other swimmers. The crux of the matter is “how well do you kick?” An efficient kick provides propulsion while limiting the drag experienced, and an inefficient kick disperses water from side to side or elsewhere and increases form drag, thereby slowing the swimmer down. A compromise should be struck between kicking big enough to drive propulsion but not too big as to increase form drag.

Lift is one of the most forgotten components of swimming yet it is one of the most important. Staying high in the water is vital yet the kick is often ignored in this quest to hydroplane and reduce drag. The flick of the kick and the up kick of the leg should provide lift – irrelevant of whether a fast or slow kick is used.

Stabilisation of counter forces in swimming is achieved by using the kick to balance out the initiation of the pull, and the rotation of the body creates a force from this motion that enables more power out of the pull or distance per stroke. This relies on strong “core” activation and kinetic sequencing. The kick not only contains up and down kicks but lateral components too. These lateral components help to stabilise rotations experienced through the body and maintain good body alignment.

The law of inertia states that an object in motion likes to stay in motion. Trying to keep swimmers in motion and maintaining a more constant speed in the water is a good enough reason to work both the up kick and the down kick. The up kick in both the flutter and dolphin kicks, the weaker of the two directions, is the most neglected part of the kick and often used as “rest”. Kicking is not easy, so it is natural to look for some recovery period in the kick and it seems logical to choose the up kick for this opportunity, since it produces less propulsion than the down kick for a similar effort. But even if propulsion is less with the up kick, by applying pressure on the water in both directions a more constant speed and more efficient swim is achieved.

 

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Let’s get a bit technical…

Why work both directions of the kick?

When a fish swims they push equally hard in both directions from side to side with their tails. As the tail moves through its path it creates a wake or vortex behind it, which, depending on the sise of the fish can extend for several feet behind the tail. Once the fish completes the path of the movement in one direction, it immediately moves the tail back in the opposite direction. Because the wake or vortex follows the tail, the tail pushes back against a stream of water flowing in the opposite direction, or toward the tail. By pushing back against this stream of flowing water, the tail is more effective and the propulsion more powerful than if it were simply pushing against still water. If one chooses to relax on the up kick then when the down kick is initiated, there is no stream to push against. The net propulsive force of the down kick is not as strong as it would have been if the up kick had been strong, creating a wake behind it.

 

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What is good kicking technique?

The down kick should be a whip like action started from flexion at the hip and followed by slight knee extension. The beginning of the up kick overlaps the end of the down kick to overcome the legs downward inertia and change its direction. The up kick should be executed with a straight leg – the most common mistake made by poor kickers is flexing the leg at the knee during the up kick. This increases resistance and form drag. The flutter kick should neither be too shallow or too deep. Body stabilisation & propulsion will be reduced if too shallow – form & pushing drag will be increased if too deep. When the down kick is completed the foot should be just below the body line.

 

The biggest mistake made when training kicking technique is training in the incorrect body position – head too high, hips too low, too much knee bend, weight on a kickboard, kicking without hip rotation, etc.

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