A body that is moving has a great deal of inertia, which makes it difficult to stop. If you can add your opponent’s momentum to your own, you will assist the speed of your technique. This is why the soft arts are often referred to as yielding; you utilize your opponent’s force against him.

Energy can be conserved by doing as little work as possible. Work in physics is defined as the force times the distance.

Work = force X distance

In essence, this means that if you utilize a lot of movement (a long distance), then, for a given force, you will be doing a lot of work, and therefore expend a lot of energy. This is why we must learn to utilize our opponent’s work to our advantage. Work can also be thought of as power times time.

For a given amount of work, the shorter the time, the greater the power. In simple terms, this means that if you can do a lot of work in a short time, you have a lot of power.

Inertia is important to conservation of energy, because every time you have to overcome inertia, you expend energy and get tired. You should try to use both your own and your opponent’s inertia to your advantage.

Conservation of energy:

1. You can conserve energy by using as little movement as possible, and relying on your opponent’s movement. An example would be to dominate the center of the ring, forcing your opponent to move around you.

2. It is more economical to strike when your opponent is moving into the strike’s path of power than when he is moving away. When throwing a spinning strike, think about the direction of the strike, and whether it will be more economical to strike when your opponent moves to your left or right.

3. If you miss with the spinning back fist, try to take advantage of your momentum by launching another strike with a looping or spinning path. Stopping the momentum and starting it again takes energy because you must overcome inertia.

Your opponent’s inertia:

1. Going with the motion of a strike or block enables you to set your counter-attack in motion. You are now feeding off your opponent’s energy. For example, if your opponent attempts a sweep, utilize the spinning motion to launch a spinning back fist.

2. If our opponent pushes you, try going with the motion of the push, or side-step and rely on his forward inertia to make him walk into your strike.

Your own inertia:

1. Allow strikes to ricochet off the target. This helps you change direction easier, and you will expend less energy. Rather than using your muscular effort to bring your strike to a stop, use your opponent’s body.

2. Leaning into a strike will starve the strike of power. Leaning also makes it difficult to snap the strike back after impact. Because your body is going forward, you must work against the weight and inertia of your own body. If you don’t snap the strike back, it will result in a push and power will be lost.

Kicking takes more energy than striking. This is because the legs are heavier than the arms. Energy, when kicking, is conserved by relying on principles of physics that allow you to use as little effort as possible. Energy is also conserved by kicking when your opponent is moving into the kick’s path of power. This allows you to use less of your own momentum to achieve an overall stronger momentum.

Body mechanics for energy conservation:

1. The side kick takes less effort to land when your opponent is slightly toward your back rather than your front. This is because the kick is usually thrown with your lead leg, with your opponent lined up with your hips.

2. The spinning back kick should be thrown when your opponent is moving into its path of power. Energy is conserved by spinning less than 180 degrees. If you spin more than 180 degrees, you will be chasing your opponent with the kick.

3. If your opponent moves toward your front, it would be economical to throw a round house kick.

4. Energy can be conserved by dropping an axe kick on your opponent’s guard and bringing his upper body forward and into your follow-up strike.

Inertia in kicks:

1. Energy can be conserved in all kicks by chambering the leg prior to kicking, and by keeping the kick lined up with your centerline. There is less inertia in the leg the closer the weight is to the pivotal point.

2. A spinning kick that is not compact is difficult to accelerate, and has more rotational inertia than a kick that is tight.

3. Low kicks use less energy than high kicks, because they don’t have to counter-act gravity. Kicking to the legs also requires less movement, and is therefore economical.

A properly executed throw will seem almost effortless. The effectiveness of a throw can be increased through the use of circular momentum. If the throw is linear in nature, it will result in your opponent going over the top; you will be carrying his weight and will expend a lot of energy.

Conserving energy through positioning:

1. Your first priority should be positioning. A superior position will restrict your opponent’s fighting ability and better your own. The best position is generally behind your opponent’s back.

2. Rather than moving yourself to the superior position, energy can be conserved by moving your opponent to the inferior position. For example, use his inherently weak neck to turn him with his back toward you.

Conserving energy through movement:

1. A joint lock is often used preparatory to a takedown. Energy in a joint lock is conserved by moving your opponent close to your center of mass, and relying on short and quick moves to initiate the takedown.

2. Energy in a throw is conserved through the use of short and quick moves, using your opponent’s momentum against him. There should be no stop in momentum, or you will expend energy on overcoming inertia.

Conservation of energy when grappling

Because of the proximity of the fighters in a grappling situation, you can conserve energy by using much of your opponent’s movement or body weight against him. Although many people think of grappling as wrestling, strikes and kicks can also be used on the ground, along with larger moves, as when repositioning from controlling the feet to controlling the head.

The use of fine motor skills and your opponent’s momentum:

1. Conserve energy through your opponent’s struggle. If you are the heavier fighter, try to maintain the top position, making your opponent struggle under your weight. If you are lighter than him and end up on the bottom, rather than fighting against his weight, try to use joint controlling techniques combined with leverage.

2. It is important to keep a close proximity to your opponent, especially if you are in the inferior position. Once your opponent reacts to the joint lock, allow his heavier mass to initiate the move. Then roll with him to a more favorable position.