Plyometrics is a form of power training that links speed and strength together so you produce a greater speed of movement. It is used for the lower body, upper body and core to enhance performance in many specific skills. By including plyometric exercises as part of your training program you will learn better balance, coordination, quickness, agility, speed and power. Plyometric training is a good addition to any routine to train explosive power through elastic energy. It is important to emphasize quality over quantity, progress the exercises using caution, and use the training wisely in your routine.

Plyometric training challenges your nervous system as well as your muscular system. This type of training is characterized by an eccentric (lengthening) contraction followed by a powerful concentric (shortening) contraction. These exercises help prepare you for athletic performance by increasing your ability to generate power. Plyometric movements involve three phases.

The first phase is called a pre-stretch (or eccentric muscle action) where elastic energy is generated and stored. The faster and greater the load during this phase, the more powerful your reflex and contraction that follows. Think about when you jump to grab a rebound in basketball or get ready to hit a close net spike in volleyball. You will jump higher the fewer steps you take because you use momentum. You create a more powerful and faster contraction by using this momentum to your advantage. With a greater load your legs will respond with a larger contraction and a higher jump height; a phenomenon that exists with all explosive actions¹.

The amortization (second) phase is the time between the end of the pre-stretch and the start of the concentric muscle action. The shorter you make this phase the more powerful your muscle will contract. A good plyometric exercise should contain a very fast loading phase so the stretch reflex can create a very fast and powerful muscle contraction. If the basketball player or volleyball player used box jumps to train for jumping, the activity would need to create this quick stretch. By jumping onto a 24-inch box from an athletic position you are training a power exercise but not a plyometric one. If you jump off a 6-12 inch box, hit the ground and bounce back up onto the 24-inch box you are performing plyometrics¹. Landing from the smaller box and loading the legs quick enough creates the stretch reflex you need.

The actual muscle contraction is the final phase where you perform the movement. This is when the basketball player has finished jumping to catch the basketball or the volleyball player has spiked the ball. The sequence of these phases is called the stretch-shortening cycle; the basis of plyometric exercises.

When performing plyometric training it is very important to be good at it before you add repetitions. Have your coach watch your technique to be sure you are performing the exercises correctly. When you land from a jump your knees might move to the left or right. It is important that they stay aligned so you can absorb the force efficiently. As with any part of your training program plan the order of exercises with the other activities you are doing that day, week, and month. Some sound principles for a plyometric workout include²:

• begin with exercises that are fast, explosive and designed for developing elastic strength (low hurdle jumps; low drop jumps)
• work through exercises that develop concentric strength (standing long jump; high hurdle jumps)
• finish with training for eccentric strength (higher drop jumps)

Another example of a session could be²:

• begin with low hurdle jumps
• progress to bounding and hopping,
• continue with steps or box work
• finish with a medicine ball workout for abdominals and upper body

Using plyometrics in your training is very taxing on your body because of the powerful forces from the stretch reflex. This force on the muscles is greater than when you perform a voluntary contraction (i.e. during a bicep curl). Your musculoskeletal system must be trained for overall fitness to support this intensity. One theory suggests that you should be able to squat twice your body weight before attempting depth jumps. You will want to condition yourself before performing any type of exercise with this intensity.

Less taxing plyometric exercises need to be included as part of a general circuit during your early stages of training to progressively condition you for this activity. Simpler skills must be mastered before you progress to more difficult exercises¹. You should first introduce straightforward plyometric drills such as skipping, hopping and bounding. More demanding exercises such as flying start single-leg hops and depth jumps should be limited until you are well conditioned².

Weight training that includes core stability exercises is also important to develop a strong base. The core musculature is involved in developing power to accelerate the body through space and absorbs shock when you land. Along with training your muscles and bones, you require good solid balance and stability to withstand the quick loading phase. The shocks from the stretch reflex are felt throughout your body so all areas must be structurally sound to support this type of power training. This includes adequate rest between routines; typically 48 hours should pass before you perform another practice of plyometric exercises. This allows your nerves and muscles to regenerate and grow.

Click the sites below for some good plyometric exercises to include in your training program. Be sure to talk with you coach before you include any of these in your workout.

http://www.exrx.net/Lists/PowerExercises.html3

http://www.refworks.com/Refworks/mainframe.asp?ExpressImport=rad170CE.tmp4

Plyometrics can be a great addition to your training program when your goal is to develop explosive power. Understanding the stretch reflex and the effect it has on your body helps you choose quantity over quality. Remember to progress from simple to complex and make smart training choices. Keep jumping as part of your routine and your ability to be more powerful with movement will be the difference to better performance.

1. Bodybuilding.com – SportSpecific.com – The Truth About Plyometrics. . http://www.bodybuilding.com/fun/ss4.htm. Accessed 6/24/2008, 2008.
2. Development of elastic strength through the use of plyometrics. . http://www.brianmac.co.uk/plymo.htm. Accessed 6/24/2008, 2008.
3. ExRx.net Power Training Exercises: Olympic Syle Weightlifts and Plyometrics. . http://www.exrx.net/Lists/PowerExercises.html. Accessed 6/23/2008, 2008.
4. Bodybuilding.com – Mike Robertson – Fun With Your (Med) Balls! . http://www.bodybuilding.com/fun/elitefts6.htm. Accessed 6/24/2008, 2008.

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