The front kick is one of the most fundamental of the foot strikes. It refers to any chambered or unchambered kick that travels along the midline path (sagittal plane), directs force in the forward direction (except for the front up kick), and connects with a target directly in front of the kicker. There are several variations of front kick, each with its own considerations.
A front snap is the jab of kicks, and done with the lead leg. It is quickly chambered and snapped out to the target (torso, face) with a modest degree of force, and returned immediately to the starting position. The striking surface is the ball of the foot. Front snaps are not done with the same follow-through as a side kick or front thrust, and speed, timing, and accuracy are the focus over power.
This type of kick is also called a teep in Muay Thai (which, coincidentally, is also sometimes delivered as a push kick).
A front thrust is a front kick designed for power, and done with the rear leg. It is chambered and driven through the target (torso) with a high degree of force, and returned immediately to the starting position or placed forward on the step through. The striking surface is the heel or whole sole. This is often the kick used to break down doors on television. It was famously used in the movie 300 when Leonidas yelled, "This is Sparta!" and kicked the messenger into the pit.
A push kick is a front kick designed for creating distance, and can be done with either the front or rear leg. It can be chambered or unchambered and instead of connecting for impact, the opponent is pushed away by the foot. The striking surface is the ball of the foot, the heel or the whole sole. This kick is typically used when a front kick is jammed or when more force is needed to push an attacker away than can be generated by the hands (victim is against a wall, doesn't want to do damage, or just wants to create distance). It is also used to set up for a different technique, such as a spinning back kick.
Front Up KickEdit
Sometimes a front kick can be delivered in a upward direction of force to the face, chin, etc, which is a hybrid of the front kick and the up kick called, aptly, the front up kick. This differs from other front kicks in that the direction of force is not forward. It is a chambered kick, and striking surface is the ball of the foot or the heel.