Plyometrics are exercises designed to specifically train the eccentric contraction phase of a muscle’s action. Eccentric contractions occur when the muscle lengthens under tension to decelerate the body. For example, when a runner’s foot strikes the ground the quad muscle must contract to prevent the leg from collapsing. Contrast this with a concentric contraction which involves contraction of a muscle while it shortens. An example would be leg extensions on a nautilus machine in the gym. The quad contracts and shortens to extend the leg and straighten the knee. Concentric type exercises are far more common and widely practiced than eccentric exercises. However, it is the eccentric phase of the running stride that wears out the quads during a race. This is primarily due to two reasons. One, eccentric contractions are harder on the body than concentric contractions. And two, specific eccentric exercises are not part of most runner’s training program. Both of these problems can be addressed by targeting the running muscles with regular eccentric exercises in the form of plyometric training.

Because plyometrics do stress the muscles and tendons more than concentric exercises they must be added to a training program gradually to allow for proper adaptation. The program outlined below is designed for the runner/triathlete as it specifically targets the major running muscles of the quads, hamstrings and calves. Also, running stresses the muscles more than cycling so these exercises are more run specific. The exercises are outlined on the handout sheets and can be referred to whenever necessary. The black boxes next to the exercise represent levels of difficulty from 1-4. Week 1 and 2 of the program are build-up weeks that prepare the legs for plyometrics. Ideally, try to do 2-3 workouts per week. The program is designed around 3 workouts per week but it can be modified quite easily. It is also designed for beginners so if you find that the exercises are too easy, simply increase the number of repetitions from 15-20. The red number in brackets after each exercise (e.g. - [1] ) indicates the intensity level associated with that exercise.

Many of the exercises involve the use of a plyometric box as an aid. This is a sturdy wooden box that can support more than your body weight. It ranges in height from 6-24 inches and should have a large surface to land on of about 18 x 24 inches. A box is not necessary, though, for many of the other exercises. For example, "Jump From Box" can be done off of the stairs or off a milk crate. The box is necessary for an elevated landing, though, as a milk crate or the stairs do not provide enough surface or stability for proper safety. If you do not have access to a box modify the workouts to include only those exercises that can be performed safely without the box.

Once you have completed Week 5 of the program your muscles should be well accustomed to the stress of eccentric exercise. At this point you should continue training with Level 2-4 exercises. Pick your favorites and mix them up so you don’t get bored or stale. When the race season starts you can maintain your eccentric strength with 1-2 workouts per week made up of Level 2-4 exercises. Cut back on the number of exercises if you feel you don’t have enough time to fit everything in. You should not have to do as many high intensity plyometric exercises to maintain your strength. Cut back during taper phases before a race. Never do these exercises if you are recovering from an injury. Regain your strength before attempting them again. Feel free to contact me if you have any questions.

Note - This program is designed for the beginner with no previous plyometric or strength training experience. If you begin following the program but find that the exercises are too easy, increase the repetitions to 20 or move to a higher difficulty level.

Descriptions and drawings of all exercises can be found by following the links to Level 1, 2, & 3 below. All descriptions of plyometrics are from the book "Jumping Into Plyometrics" by Donald A. Chu (Leisure Press, 1991).


taken from http://www.webgate.net/~welchiro/plyometrics.html