Don't Deliberately Injure Muscles During Workout, Experts Say

Reviewed by Gary D. Vogin, MD
From the WebMD Archives

July 17, 2001 -- In an effort to get big and strong, athletes and bodybuilders will try just about anything. One type of exercise that is increasingly popular is called eccentric muscle training, a method that's known to injure muscles more than other types of strength training. That's considered a good thing, because injured muscles grow quickly as they're repairing themselves. The theory has been, therefore, that eccentric training will allow athletes to build bigger muscles faster.

A new study, however, questions the validity of that thinking.

A weightlifter is performing concentric muscle training when doing exercise that contracts the muscles, and eccentric training when it extends the muscles. The idea that eccentric training can lead to better and faster results for weightlifters is an appealing one, says study author David Jones, PhD, professor of sport and exercise sciences at the University of Birmingham, England -- but, unfortunately, it's not been borne out by scientific studies.

"Strength training is an integral part of most athletes' routine, but surprisingly little is known about what specific aspect of weight training causes muscle to grow and become stronger," he says.

For their study, Jones and his colleagues asked 26 healthy adults to perform eccentric training exercises with one arm and regular training (which combines eccentric and concentric movements) with the other arm for three days a week over a nine-week period. Their research is published in the latest issue of the journal Medicine and Science in Sports and Exercise.

According to co-author Jonathan P. Folland, PhD, lecturer in nutrition and physiology at the University of Brighton, England, his team found that "severe eccentric muscle activity ... causes delayed onset muscle soreness and muscle damage [but] is not beneficial in the early stages of a strength-training program. This type of training will actually make you weaker for several weeks than just standard training."

Exercise physiologist Howard Panes, CSCS, says eccentric muscle training has led to an ongoing controversy among sports medicine experts, as well as athletes and serious bodybuilders looking to optimize performance and muscle size. These individuals might benefit from some mild eccentric exercise, he says, although it increases their risk of injury, especially if they don't exercise regularly. Further, the method only seems to work in some people, as genetics and muscle fiber type appear to play a role in who sees the most benefits.

"Eccentric loading alone is very dangerous, because you're loading the muscle in its weakest position. ... There's [also] more risk for injury. All injury happens when the muscle is eccentrically loaded," says Panes, CEO of How Fit Inc./NRG Ball Training Systems in Livingston, N.J. He was not involved in the research.

For weekend warriors and those who exercise just to keep fit and healthy, the best and safest way to train is to use the standard weight machines available at the gym, says Panes. These machines carefully balance concentric and eccentric movements for a safe and effective workout.