The crescent kick, also referred to as a "swing" kick, has some similarities to a hook kick and is sometimes practised as an off-target front snap kick. The leg is bent like the front kick, but the knee is pointed at a target to the left or right of the true target. The energy from the snap is then redirected, whipping the leg into an arc and hitting the target from the side. This is useful for getting inside defenses and striking the side of the head or for knocking down hands to follow up with a close attack. In many styles of T'ai chi ch'uan and Kalaripayattu, crescent kicks are taught as tripping techniques. When training for crescent kicks, it is common to keep the knee extended to increase the difficulty. This also increases the momentum of the foot and can generate more force, though it takes longer to build up the speed.