Before undertaking serious plyometric training, it is important that you first develop a strength base. Since the force developed in some types of explosive training can reach 20 times your body weight, it is easy to see why you must be strong enough to withstand such forces. This means that you mst develop concentric, eccentric, and isometric strength since all three of these muscle exercise regimes are used in plyometrics (explosive training).
When you start training you should first go on an all - round total body conditioning program. You should do exercises to develop all the muscles of the body and all the joints in all of their actions. This type of training should last between 1 - 3 months, depending upon your initial level of fitness. Once this general base is well developed, you should then bein to do strength exercises which more closely duplicate the actual movements involved in your sport(s), including plyometrics. The more specific the exercises, the greater will be the effectiveness of your workouts.
The development of explosive strength is more complex, and four methods are used. They are:
Exercises with weights are used to develop maximum absolute strength. Weight exercises are also used in combination with jump exercises or in series with them. One simple routine to develop explosive power is to assume a specific position and hold it for 3 - 5 seconds to develop isometric tension. Once the muscle is prepared, you explode in the opposite direction with maximum speed. For example, go into a squat and hold the bottom position, leap up as high and as quickly as possible. This helps to develop explosive legs.
To develop explosive arms with this method, you can do an exercise such as lying on your back on a narrow bench holding a weighted medicine ball in your hands with the ball almost touching your chest. Hold for 4 - 5 seconds and then throw the ball upwards with maximum force. A barbell or dumbbells may be used instead of the medicine ball, with the obvious exception that you won't throw the weights.
Jump exercises are the simplest form of plyometrics. The jumps are usually done in series of approximately 10 jumps. They can be done on both legs or on single legs or alternating between legs. However, when first beginning you should ALWAYS do double leg jumps up until your legs (or arms) become accustomed to the jumping. Remember that the amount of eccentric force generated in a single leg jump is about twice that of a double leg jump and if your muscles are not prepared for this force, it may be injurious.
Next in progression are series of jumps having different directions, jumping over various objects and jumping onto and off various objects. For example, you can jump sideways, then forward, and then backward. Or you can jump in a zigzag fashion. It is also possible to jump with body turns so that you end up facing in different directions after you execute the jump. All body turns made while you are airborne.
Jumping over objects becomes more effective than simple jumping because it forces you to jump a little higher, which, in turn, creates more force upon the landing. In turn, allowing for greater development, which, in time, allows you to jump even higher. Also, by jumping onto and off various objects it puts more variety into the program as well as exposing your nervous system to experience different amounts of force from the different jumps. This also provides for greater development.
Next in the progression are altitude jumps, a term coined by Fred Wilt, which are an example of the hit or shock method. In essence, you step off from various heights and upon landing you undergo minimal flexion of the legs (or arms) which forces the muscle to stretch sharply and undergo maximum tension. This happens automatically and your mind is not involved in developing maximum tension. This is why this method is so effective. It produces a greater force than you would produce on your own.
In general, for highly trained athletes with great absolute strength, the altitude jumps are done from a height of approximately 5 - 6 feet and more. When first beginning you should begin with low heights of approximately 2 - 3 feet and gradually work up to 6 feet or more. Studies have shown that jumping off from heights of 9 feet or more are counterproductive and the athletes are hesitant to jump from such heights.
The main reason for using altitude jumps is to develop supermaximum strength, i.e., maximal eccentric strength. To do this, it is necessary to use exercises in which the muscles are forced, under the influence of significant external forces, to execute work in the eccentric range. The load must be such that it forces the muscles to contract at the upper limit of their supermaximal strength for a very brief period of time.
In the altitude jump, upon landing from a height of 6 - 7 feet, the extensors of the ankle, knee and hip joints and the spine are forced to execute eccentric work under the influence of inertial forces. In these brief conditions the athlete develops the ability to display brief muscle tension during which the force reaches values that are fantastic at first glance. It fluctuates from 1500 - 3500 kg, i.e., they exceed your weight by 20 or more times.
A person is not able to achieve such strength in other exercises, only in altitude jumps, which are excellent stimulators of muscle strength. The altitude jumps used for strength training must be done on soft gym mats or a well dug hole with sand.
Altitude jumps in which the muscles under the influence of large external forces execute only eccentric work. In eccentric work, there is maximum tension in the shortest time. This facilitates the growth of strength in eccentric and in concentric movements.
Depth jumps is the most popular and most effective method for the development of explosiveness. It is also the most effective method for developing the reactive ability of your neuromuscular system. When the muscle is stretched, it develops elastic strength. This not a metabolic process, it is purely physical.
To execute depth jumps, you step off a box or bench set at a certain height so that you drop straight down. As soon as you hit the floor, you immediately jump straight upward or upward and forward, with as little bending of the legs as possible. All of the landing forces should be vertical so that they can create maximum loading on the muscles.
Landing should take place on resilient mats such as gymnastic or wrestling mats. Also, in the landing you should land first on the balls of your feet and then on the whole foot, followed by the ankle, knee and hip joint flexion. Note that the amount of flexion should be minimal. The key to success in the depth jump is a maximum fast twitch from the eccentric contraction to the concentric. The faster the switch takes place, the greater the force produced and the greater will be the height of the take - off.
To execute the depth jump explosively, you should start thinking about the take - off prior to the landing. In other words, prepare your body for the landing and take - off and do not just allow it to happen. To do this most effectively you must get yourself psyched for a maximally fast and forceful jump.
Do not begin the jump up until after you land. You must allow the muscles time to sharply stretch and tense.
The most effective height for the depth jump is between 30 - 40 inches. When first starting you should use a lower height until you get used to the mechanics of the depth jump. When your muscles are prepared, then go to a height between 30 - 40 inches. As a general rule-of-thumb, your depth jump height should be no more than a foot above your vertical jumping ability.
At a height of 30 - 40 inches, the amount of speed and strength is well balanced and you get the maximum effect of both of these physical qualities. If you increase the height from which you step off, then you would rely more on the strength component and if you lower the height, you will rely more on the speed component. By adjusting the height of the depth jump you can variably improve more strength or speed.
Depth jumping from too high a height typically happens with beginning and intermediate athletes who usually function on the principle "more is better". Because of this, they increase the height to amounts that are beyond their capabilities to execute the jump effectively. When you jump from too high a height, there is too much flexion in the legs, which absorb most of the force of the landing, and thus there is very little force to propel you upward. You end up with a weaker and lower jump. Jumping from too high a height also involves different take off mechanisms.
It is also important to realize that it is most advantageous to execute depth jumps after adequate strength preparation. Because of the great forces involved, it is necessary to begin doing such exercises very gradually. Practice has shown that in most cases you should be able to squat 2.5 times your body weight before undertaking maximum depth jumps. You should also know that the after effect of the depth jump is maintained for about 6 - 8 days. Because of this, such jumps should be discontinued 10 - 14 days before competition.
How often you jump is also important. For athletes who are well prepared physically, doing depth jumps three times a week is usually sufficient for most sports. Also, the number of depth jumps in one session should not be greater than 40 times. For less physically prepared athletes, 20 - 30 repetitions of the jump one time per week is enough.
Although there is some variability, depth jumps are executed in series (10 times from a lower height and 10 times from a slightly higher height). Two sets are done. In between each set you should do light running exercises and exercises for relaxation (stretching).
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