1.) Focus on the “up kick”
Often times when swimmers start learning the dolphin kick, their emphasis is on the down kick. This is for a couple different reasons, but the main one being that a swimmer creates the majority of their propulsion in this downward phase. About 80% of the propulsion created in the dolphin kick comes from the down kick. The other 20% comes from the up kick.
Ideally, a swimmer should bend their knee to at least 30-degrees during the up kick phase–but no more than 90-degrees. An excessive knee bend can be detrimental to the dolphin kick as a whole.
In order to create the maximum amount of propulsion possible, a swimmer must activate their glutes and hamstrings, along with forcefully bringing their heels back towards their bum and bending their knees. From this loaded position, a swimmer then plantar flexes their feet and forcefully extends the knee while contracting the quadriceps muscle to create a powerful and quick down kick.
If any phase of the up kick is not done well, then the following down kick will not be as powerful. The up kick is like pulling back an arrow on a bow and arrow. In order for the arrow to fly far and with speed, one must put the proper amount of tension on the string. A loaded string will always fly an arrow further and faster than a relaxed or slightly contracted string.
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