Plyometrics may be a completely new concept to some, but it has been around for years. Plyometric training has long been a staple of athletes who need to work on their explosive strength. Even so, there isn't much published scientific information on this fairly simple training technic: a search of research studies using the term "plyometrics" on PubMed retrieved only 23 scientific citations, and a similar search in the "Books" section of Amazon.com identified 20 book titles. However, a similar search on Google retrieved 473,000 pages (all searches performed January 23, 2006).

DEFINITION

The actual term "plyometrics" was first coined in 1975 by Fred Wilt, one of America's more forward-thinking track and field coaches. Based upon Latin origins, "plyo" + "metrics" is interpreted to mean measured increases. Plyometrics describes any exercise where the muscle is stretched (ie, loaded) before it is contracted. "Plyometrics is defined as exercises that enable a muscle to reach maximum strength in as short a time as possible. This speed-strength ability is known as power," says plyo expert Donald A. Chu, PhD. An example of plyometrics exercise is jumping off a platform then rebounding off the floor onto a higher platform.

BACKGROUND

Plyometrics exercises have their roots in Europe, where they were first known simply as "jump training". Interest in jump training increased in the early 1970's as East European athletes emerged as powers on the world sport scene. These seemingly exotic exercises were thought to be responsible for the rapid competitiveness and growing superiority of Eastern Europeans in track and field events. Plyometrics quickly became known to coaches and athletes as exercises or drills aimed at linking strength with speed of movement to produce power. Plyometric training became essential to athletes who jumped, lifted or threw.

Plyometrics is one of the best ways to improve power. Power is similar to strength with the addition of a time factor. If strength is how much weight a muscle can lift, then power is how fast it can be lifted. A person who can perform a specific resistance movement, such as jumping, bench press etc., the fastest would be said to have more power in that movement. It has been shown that a muscle will contract the fastest when it has been loaded. This is why you should be able to jump higher if you crouch down then immediately jump up than if you started in the crouch.

PLYOMETRIC EXERCISES

Elite athletes incorporate plyometric lower body exercises into their training program to enhance their speed, quickness, and agility. However, it is possible to design plyometric exercises for the upper body as well. The average person will probably not do these exercises, but anyone can incorporate basic plyometric-type moves into their workout to add more intensity and challenge.

Before you get started, keep in mind that plyometric training:

• Requires both strength and endurance. If you've never done these types of exercises, make sure you've been exercising consistently for at least 3 months. Make sure you include some weight training in your program before you begin plyometric exercises.

• Should be added very slowly and in short intervals. Begin with 10-30 seconds per exercise and slowly work up to 1 minute. In between, walk in place until you recover.

• Is very intense! Make sure each plyometrics session is followed by a day of rest. In the beginning, these types of exercises should only be done about once a week. It's easy to injure yourself with this type of training, so be cautious.

PLYOMETRIC EXERCISES FOR INCREASING JUMPING ABILITY

There are many different plyometric exercises designed to increase vertical leap but here are a few good ones:

Stair or Step Leaps:

If you use a step, begin with the platform at its lowest level (progress by adding risers). Stand in front of the step, brace your abs, bend your knees and jump onto the step with both feet. Step down and repeat for 10 seconds to 1 minute.

On a staircase, simply hop up the stairs, landing with both feet on each step. Each time you leap, brace your abs, bend your knees and use your arms to help you keep your balance. If you can't land with both feet simultaneously, stagger your landing and work your way up to both feet.

Plyo Lunges:

Stand in a split stance, right leg in front and left leg in back. Bend knees into a lunge (keeping front knee behind toe) and, in an explosive movement, jump up, switch legs in the air and land in a lunge with the left foot forward. Go as slow as you need to to keep your balance. Go faster, jump higher and/or lunge lower for more of a challenge.

Side-to-Side Lateral Jump:

Place a piece of tape on the floor. Stand with both feet on one side of the tape so that the tape forms a line to your side. Bend your knees into a slight squat. In an explosive movement, jump sideways over the tape, landing with knees bent into a squat. Continue jumping from side to side for 10 seconds to one minute.

As you get better at it, you can use larger objects (such as a small ball or a step). If you use a step, you can ease into this exercise by standing sideways to the step, jump on top of the step and then step down on the other side (it's better not to jump off the step). Be VERY careful to use objects that won't slide if you land on them! Start with an object you can easily clear when you jump.

Plyo Jumps:

Stand with feet together. Bend your knees into a squat and then jump up as high as you can. Land with knees bent (to protect your joints) and immediately go into a squat and repeat the squat/jump for 10 seconds to 1 minute. Raise your arms as you jump to add more intensity.

Two Foot Ankle Hop (low intensity):

With your feet together and remaining in one place, hop up and down using only your ankles and calves. Concentrate on getting as high as you can and exploding off the ground as soon as you land.

Rim Jumps (medium intensity):

Stand under a basketball rim. Jump up touching the rim (or net) with alternate hands. Concentrate on getting as high as you can and exploding off the ground as soon as you land.

Box to Box Jumps (high intensity):

Place two boxes that will support your weight about 3 feet apart. Standing on one box, step (DON'T JUMP) down to the ground and immediately jump back up to the other box. Turn around and repeat. Obviously the difficulty of this exercise is increased as the height of the boxes is increased. Once again concentrate on getting as high as you can and exploding off the ground as soon as you land.

These exercises can be combined. For example, try stepping off a box before jumping up to the rim.

PLYOMETRIC EXERCISES FOR INCREASING SPEED

While all of the above exercises will also increase your speed (leg speed), there are many others that focus more on movement. Here are some examples:

Single-Leg Hops (medium intensity): Place an elastic cord about 12-inches off the ground. While on one foot, hop back and forth over the cord. Repeat with other foot.

Side-to-Side Ankle Hops: Same as regular ankle hops (see above) but instead of remaining in place, jump 2 to 3 feet side to side.

Sprints: Sprinting is an example plyometric training on the hamstring. Each time your body weight lands, your hamstring is being loaded and then immediately forced to contract.

PLYOMETRIC EXERCISES FOR THE UPPER BODY

Push-Ups: Clap your hands together between each push-up. At the end of each "descent", just before your chest touches the ground, immediately push up again as hard as you can. Begin each new push-up without any hesitation between each one.

Medicine Ball Exercise: Lie flat on your back and have someone drop a medicine ball towards your chest. As you catch it, let it drop until it is within inches of your chest and immediately push the ball straight up as hard and as fast as you can.

QUESTIONS

Q: What are "strength shoes"?

ANSWER: It is a shoe with an elevated sole, but the sole only covers the ball of the foot. The heel is allowed to hang free forcing the calf to be stretched (ie, loaded) on every step. Strength shoes do work; every step becomes a plyometric exercise for the calf. Since strength shoes only work the calf, you must do other plyometric exercises to work the other muscles.

Q: Can you get injured by doing plyometrics?

ANSWER: If ballistic stretching is not recommended due to the possibility of injury (see separate story "Stretching"), then certainly abruptly lengthening then contracting a muscle against most of your own body weight would seem to be risky, too. Since so many exercises could be considered plyometrics, of course some of them are dangerous. Jump squats are a great example. This exercise utilizes about one-third of your body weight. While this is one of the best exercises to increase your jumping ability, unfortunately it is also a dangerous one.

Plyometric exercises are not recommended for those who have a bad back or knees. On the other hand the two foot ankle hop is very safe, and will offer good benefits. A good general test to see if you are ready for plyometrics is to jump up as high as you can. Measure this height (put chalk on your fingertips and touch the wall). Then step off an 18-inch box and immediately spring up as high as you can. If the plyometrics-type jump does not exceed the height of your standing jump, you should first do some weight training on your legs before beginning plyometrics exercises.

SUMMARY

In the exercises described above, you are using your body weight and gravity to load the muscle immediately before contraction. The forces you generate are much larger than could be safely accomplished using conventional exercises with weights. Although these forces only stress (load) the muscle for a very brief moment, a training response (on the muscle group) can still be produced.

Tips for doing these exercises:

• Make sure you warm up before you start.

• Add them at the end of your usual workouts or sprinkle them throughout your workout.

• Alternate each exercise with recovery periods on those days when you don't have a lot of time but want a challenging workout.

• Do each exercise for 10 - 60 seconds and always recover with a few minutes of walking or light cardio before you repeat them. You can repeat them more often or for longer intervals to progress.

• All exercises are high impact. When you land, make sure your knees are bent to take the stress off your joints. Obviously, the lower you squat and the higher you jump, the harder the exercises will be.

FOR MORE INFORMATION

www.PlyoCity.com is a web site describing the preeminent plyometric training program in the US. On their web site, they claim to have trained over 30,000 athletes in the past 8 years, including many world-class athletes.

The November 2004 issue of Runner's World magazine contains a short article on plyometrics. It demonstrates 4 exercises for runners: vertical jump, split jump, standing long jump, and ankle hops.

Jumping Into Plyometrics is in its 2nd edition. It is written by Donald A. Chu, PhD, one of the leading authorities on plyometric training for athletes.

Athletic Strength For Women by Oliver and Healy has a chapter on specific plyometric exercises.

Training for Speed, Agility, and Quickness by Lee Brown, Lance Ferrigno, and Juan Carlos Santana, and, Sport Speed and Agility, by John Cissik and Michael Barnes, contain information on speed and agility drills for athletes.

EXPERT HEALTH and FITNESS COACHING

Stan Reents, PharmD, is available to speak on a variety of exercise-related topics. (Here is a downloadable recording of one of his Health Talks.) He also provides a one-on-one Health Coaching Service. Contact him through the Contact Us page.

ABOUT THE AUTHOR

Stan Reents, PharmD, is a former healthcare professional. He is a member of the American College of Lifestyle Medicine (ACLM) and a member of the American College of Sports Medicine (ACSM). In the past, he has been certified as a Health Fitness Specialist by ACSM, as a Certified Health Coach by ACE, as a Personal Trainer by ACE, and as a tennis coach by USTA. He is the author of Sport and Exercise Pharmacology (published by Human Kinetics) and has written for Runner's World magazine, Senior Softball USA, Training and Conditioning and other fitness publications.