Cutting off is the term used for the motion of constantly moving toward the opponent's off side, or mirroring the opponent's movement and not following the opponent's movements. This prevents the opponent from "setting" and putting extra power into a punch or kick. If the opponent has the left foot forward, the opponent's off side is toward the opponent's left, and vice versa. When you keep moving to the opponent's off side, the opponent is unable to "set" for an attack. You are moving away from the opponent's power side (the rear hand or foot), which will weaken their striking force, and you are angling toward the outside of the opponent's weak side (the front hand or foot), which weakens their striking force.
The cut off is used to slow down and contain a fighter so you are able to score. You are taking the ring away from the opponent, so he or she is unable to stick-and-move or fight you at his or her favorite range. You are controlling movement within the ring to your advantage. When you control the ring, you control the action, and you control your opponent. A controlled opponent will get frustrated and start making mistakes. Be ready for openings and take advantage of them; this will frustrate the opponent even more.
How to cut off
The ring is a square. Imagine the ring is divided into four smaller equally sized squares by a lines that cross at the center of the ring. As you are moving about the ring, never let your opponent turn and cross one of these imaginary lines. Cut the opponent off by mirroring his or her movement, not by following him or her. Stay even with the opponent and stop his or her movement by throwing hooks in the direction he or she wants to move, this techniques is known as "hooking off" the opponent.
When you have an opponent in a corner, imagine it is one corner of a triangle and keep the opponent contained within the triangle. Keeping giving the opponent smaller and smaller boxes to work within, not allowing room for the opponent to roll out. If an opponent turns a corner and passes over your imaginary line, immediately adjust and start a new box. Move forward and toward the opponent's off side, not backward.
To practice cutting off
To practice using the cut off, you will need a sparring partner. Practice using the center of the ring, on the ropes, and in a corner; taking turns being the pursuing puncher. Change partners periodically so you get experience with different size opponents.
Make a game of it. Train with a few pairs of fighters. Every time a fighter turns a corner, he or she gets a point. Keep taking turns, giving each partner a minute to earn a point. Keep the punching very light; this is not a hitting drill, it is a footwork drill. The winner is the fighter with the most points at the end of the drill.