Many swimmers miss out on generating maximum propulsion in the breaststroke kick because they don’t bring their feet together as they straighten their legs. If you straighten your legs before you bring your feet together, your legs will be in a weak and awkward position to generate force.
A powerful kick requires that the feet touch immediately after the legs straighten. It is important to control the knees so that they separate about hip width. As the backward foot motion begins, bring the feet together. If the legs are in a strong position throughout the propulsive motion, the feet come together at a fast speed. Feeling the feet touch with a lot of force at the finish of the kick is one of the most important cues for breaststroke.