Exercise builds strength, but shouldn''t be performed by inexperienced athletes

Athletes are always looking for a way to run faster, jump higher and get stronger. More and more of them are turning to plyometric exercises as an alternative workout in hopes of gaining that competitive edge.

Matt Matava, MD, Washington University School of Medicine orthopedic surgeon at Barnes-Jewish Hospital and St. Louis Rams team physician, says plyometric exercises are considered an advanced strengthening technique and shouldn''t be performed by "weekend warriors."

Dr. Matava says plyometrics uses a method of strengthening the muscles that involves stretching of the contracting muscle or muscles to replicate activities that occur in various sports. Muscles contract in one of three ways.

Eccentric — When the muscle is being stretched, it''s called an eccentric contraction. Lowering yourself from a chin-up position would be an example of eccentric contraction.

Concentric — When the muscle is being shortened, it''s called a concentric contraction. Lifting yourself into a chin-up position would be an example of concentric contraction.

Isometric — When the muscle is contracted but doesn''t change in length, it''s called isometric contraction. Bending your arms at a 90-degree angle while hanging from the chin-up bar would be an example of an isometric contraction.

"Plyometrics emphasizes the eccentric phase of muscle contraction, immediately followed by the concentric phase of muscle contraction," Dr. Matava says. "The most common way muscles are injured is in the eccentric mode."

Some local high school and collegiate coaches are starting to introduce plyometrics to their respective teams. Dr. Matava cautions that a trainer with a background in plyometrics should monitor such training at the high school and collegiate levels. He says this form of training places a massive strain on unconditioned muscles, joints and bones and is a common source of injuries.

Dr. Matava stresses that coaches and parents should use common sense if they''re going to introduce plyometrics to their teenager or team. "The explanation I would give to my son as to when he could start doing plyometrics would be when his growth plates are closed because of the kind of stress you''re putting on the upper and lower extremities to do these exercises," Dr. Matava says. "The growth plate is the weak link between the bones, the muscles and the ligaments. When you put a compressional or contortional force on these joints, it''s the growth plates that often suffer. For girls, growth plates close somewhere between ages 13 and 14, and for boys, between 15 and 16."

If monitored by a trainer, Dr. Matava says an athlete can build strength and power through plyometric exercises that are specifically designed for his or her sport or the position the athlete plays. Rams strong safety Adam Archuleta is such an example. He''s considered the "poster boy" for plyometrics.

As a walk-on player at Arizona State University in the late 1990s, Archuleta wasn''t initially offered a football scholarship because he was considered too small to play. He began a plyometric regimen with a professional a trainer. By the time his senior year wrapped up, he was named the conference''s defensive player of the year. Later that summer, still considered too small — 6-feet, 210 pounds — to get a sniff from the National Football League (NFL), he impressed scouts at a pre-draft camp with numbers never achieved before by a player at his position. He ran the 40-yard dash in 4.42 seconds, had a vertical jump of 39 inches, and bench-pressed 225 pounds, 31 times. His best one-time bench press was 530 pounds.

The Rams gobbled him up in the first round of the 2001 draft.

Archuleta was quoted as saying in Pro Football Weekly at the time, "The results (of plyometrics) don''t lie. And the kind of football player that was made doesn''t lie either."

"What any athlete, or Adam, is trying to replicate when doing plyometrics is normal athletic activity," Dr. Matava says. "For example, taking a barbell with a certain amount of weight on it and pushing it upward 10 times is certainly good to strengthen the muscle, but it doesn''t reproduce anything he would do in a football game.

"However, an example would be, he stands on a box. He jumps off the box and lands on the ground. There''s going to be some inertia and gravity that''s going to be pulling his body downward," Dr. Matava says. "After he hits the ground, he then explodes and jumps upward. The muscles that are being contracted to have him explode upward are now being stretched because of the force of having to slow his body down when falling to the ground. That is similar to just one play in football and is probably being replicated much more by plyometrics than by weight on a barbell."

Dr. Matava says plyometric exercises also are used in the latter stages of rehabilitation to prepare muscles to handle the additional strain of the muscles being stretched — eccentric contraction.

"Plyometrics is not a means of exercise that should be taken lightly," Dr. Matava says. "It''s not a means of exercise that should be done in the initial phases of rehabilitation — it''s an advanced rehabilitation technique. It also shouldn''t be undertaken in the initial phases of someone who wants to start a weight training program to get stronger."

Written by Brian Bretsch and originally published in the July 25 issue of BJC TODAY.