Coaching points for the technique of the eggbeater kick in synchronized swimming based on three-dimensional motion analysis.

We investigated coaching points for the technique of the eggbeater kick in synchronized swimming. The movements of the eggbeater kick for six female synchronized swimmers, all the top-ranking members at the Olympics and World Championships, were analyzed by using three-dimensional motion analysis. By comparing the movements of higher eggbeater-skilled swimmers with lower eggbeater-skilled swimmers, the coaching points for techniques of the eggbeater kick in synchronized swimming are clarified as follows. First, to hold the knees as high and as near the water surface as possible and to keep the heels close to the hips. Secondly, to keep the knees as wide as possible. Thirdly, to kick sideways producing lift force, and not to kick downward. Fourthly, to pull up the heels to nearly the water surface at the out-kick, with strong internal rotation of the thighs. Lastly, to move the feet as if treading water, with strong dorsiflexion and plantar flexion and adduction of the foot; that is to move the feet like the motion of the hands when sculling. Moreover, the movements of higher eggbeater-skilled swimmers can be termed 'horizontal kick type' and the movements of lower eggbeater-skilled swimmers can be termed 'vertical kick type'.