Excerpted from Warrior Speed by Ted Weimann
Plyometrics are dynamic, explosive muscular contractions. Therefore, plyometric training involves inherent risks associated with the exercises. It is more important to be thoroughly warmed up before conducting plyometric training than it is with any other type of training. The warm up also increases the sensitivity of the muscle spindle, which houses the fibers that register the amount of stretch within a muscle. These fibers are called intrafusal fibers. The intrafusal fibers are wrapped with nerve cells. When the intrafusal fiber is stretched quickly, the nerve cells send a signal to the central nervous system (CNS.) The CNS triggers a muscle reflex (referred to as the stretch reflex) that generates a fast, powerful contraction. The purpose of the contraction is to stop the stretching and hopefully prevent injury. The more sensitive a muscle spindle is due to having been warmed up, the more stimulation the CNS receives from the intrafusal fiber and its adhering nerve cells. The more stimulation the CNS receives, the more forceful the contraction is. Therefore, warm up thoroughly to decrease the risk of injury and to increase the effectiveness of the training. After a general warm up has been performed, warm up the specific body parts about to be engaged in the training. This warm up should include the same movements that constitute the plyometric exercises.
When the intrafusal fibers are stretched, they store energy, ready to assist the muscle in contracting back to a safer length. This stored energy increases both the speed and power of your movements because it is like having a bungee cord contract along with the muscle.
Plyometric training increases the strength of the intrafusal fibers. This in turn increases the amount of energy they can store. An increase in stored energy directly increases the speed and power of the contraction. The intensity of the training of the stretch reflex is a factor of the speed and depth of the muscle stretch. The faster the muscle is stretched and the degree to which it is stretched, determine the amount of training stimulus placed upon the intrafusal fibers. Do not sacrifice speed for degree of stretch. Speed is the most important factor in determining the intensity of the stretch reflex training.
The sequence of your training should be as follows. First, warm up and stretch thoroughly. Then perform any speed training drills you wish to for the day. The speed drills must be performed before you become fatigued. Otherwise, you will not be moving at your maximum speed and, therefore, you will not be adapting your neuromuscular system to perform at top speed. Next, perform your techniques and sparring. Follow this up with plyometric training. End the training with resistance training if you include it in your workout. Relaxed stretching is an effective method of cooling down following a workout. This is also a perfect way to lead into any type of meditative training that you may employ.
The sequence of your plyometric training should be as follows. Start with rhythm plyos, followed by speed plyos and conclude with power plyos. Rhythm plyos are good for making sure you are thoroughly prepared for the upcoming exercises and they help build coordination and balance. The speed plyos should be performed before the power plyos because the speed of execution is the key. If you are too tired to perform them at a sufficient speed, you will not realize the desired results. It is of utmost importance to perform the speed plyos with the fastest possible movements. By forcing your muscles to contract in a shorter period of time in which they are accustomed to, you increase your overall capacity for speed and power.
Lower Body Plyometrics
There are many ways to perform plyometric exercises for the lower body. To help reduce compression shock on the lower back, knees and ankles, they should be done on a soft surface. Pads, grass or sand work well. The basic plyometric exercise can be used to train for rhythm, speed and power plyos. This is the hop jog. As with any plyometric exercise, first do rhythm plyos until you develop the coordination and neuromuscular adaptations necessary to train at a more intense level. If you are a highly conditioned and coordinated athlete, you may be ready to try some speed and power plyos on your second training day. It is not recommended that you move on during the first day.
Rhythm Hop Jog
This exercise is basically a slow jog, except that every time a foot contacts the ground, you leap off it as quickly as possible. The hop jog is distinctly different for speed and power plyos. Perform hop jog plyos slowly in both speed and power fashion until you feel comfortable with both techniques. With rhythm plyos, do not strive for speed or power. Your goal is to execute the exercise in a smooth, coordinated and rhythmic fashion. These should be performed as a warm up before speed and power plyos.
Power Hop Jog Plyometrics
First perform rhythm plyos to ensure that you are fully warmed up. When ready to begin with power hop jogs, start from a very slow jog. After three or four steps, hop off the right foot as high as possible. When the left foot contacts the ground, reduce the amount of time that it is in contact with the ground as much as you can. Spring off the left foot explosively, attaining as much height as you can. Continue until each leg has made eight to ten hops. The two important factors are height (determining the amount of force your muscles must quickly generate) and the length of time that the foot is in contact with the ground.
Speed Hop Jog Plyometrics
First conduct the exercise in the rhythm mode until fully accustomed to it and as a warm up before each plyometric workout. Speed hop jog plyos are the same as the power plyo exercise described above except that it has only one emphasis, speed. The height attained is not important. The length of time that the foot is in contact with the ground is of utmost importance. If you hop too high, you will not be able to spring off the ground fast enough to stimulate the neuromuscular system to adapt.
When performed properly, this exercise feels more like a skip than a hop. Since hopping up slows the muscular contractions down too much, it is necessary to hop forward. If the right foot is driving off the ground, the left leg swings forward, almost straight. When the left leg contacts the ground, it drives forward with a strong pulling action of the hamstring muscles. In this method, the foot is in contact with the ground for only a small fraction of a second.
Two-Legged Speed Hops
The basic movement of the two-legged hop plyos is the broad jump, performed repeatedly. For two-legged speed hops, this exercise is the same as the standard broad jump except that all movements are kept short and quick. The legs do not bend much and the arms do not have time to swing fully. Hop forward ten times, each time making sure that the feet are in contact with the ground for as little time as possible. Attaining approximately a two-foot distance while not bending the legs much should help you avoid having too long of a muscular contraction. This provides sufficient stimulus for adaptation. Attaining more distance frequently leads to losing your balance.
Two-Legged Power Hops
Two-legged power hops require that you drive up as much as possible, only moving forward about 18 to 24 inches. Compared to two-legged speed hops, the knees bend considerably more, the arms drive up much more, and the legs handle considerably more force. Think of two-legged power hops as a kangaroo hopping at full speed and two-legged speed hops as your attempt to hop across a hot lava field without burning your bare feet.
If this exercise feels awkward, try performing the same exercise on one leg. Use the same principles outlined above for both speed and power one-legged hops. Unlike the hop jog, there is no changing of legs. The same leg that begins the exercise continues for the set of eight to ten repetitions.
Another more advanced exercise is to jump off a one or two foot high platform. This should only be done on a soft surface as this exercise can be especially hard on the knees and back. Jump off a chair or other platform, landing on both legs. For speed plyos, do not jump off anything over 18 inches and do not jump upward when you take off from the platform. Jump straight out so that you do not fall from a height greater than 18 inches. Of course, the instant your feet hit the ground, explode back up. You can immediately follow up with a second two-legged hop if desired. For power plyos, you can jump off a slightly higher platform or jump up a little. Or you can land with the knees bent a little more.