Shin guards significantly reduce lower extremity injuries in soccer, according to a study performed at the Institute for Preventative Sports Medicine in Ann Arbor, Michigan. The study, which will appear in the April issue of the Clinical Journal of Sports Medicine found that shin guards reduced the force delivered by a kick to the leg by 41.2 to 77.1 percent and thus significantly reduced the risk of injury.

The area of the shin is the third most common area injured in soccer. Such injuries commonly occur when players try to kick the ball and instead kick each other. "Collisions are not as common in soccer as they are in a sport such as American football," said David H. Janda, M.D., Director of the Institute and co-investigator in the study. "However, contact is common and can lead to serious injuries due to the higher speed at which soccer is played." These injuries include fractures of the lower leg bone (tibia).

The researchers used a Hybrid III crash dummy similar to the crash dummies developed by the automotive industry to assess safety in auto accidents. Similar in size to a ten-year-old child, the Hybrid III dummy measures more factors and more closely mimics whole body responses of humans than other approaches. A free swinging pendulum device delivered a force similar to that of a high impact collision during a game to the knee of the dummy. This simulated one person kicking another person with their leg planted, and represents the impact a healthy, physically active athlete could deliver with a kick. The researchers fitted the shin guards to the leg with straps in the manner in which a player would typically attach the guard.

The researchers tested 22 different commercially available shin guards. Each shin guard was hit five times with the pendulum device at three different temperatures. This represented the average and extreme temperatures that might be encountered during the play of soccer. The study found that all shin guards demonstrated at least a 40 percent reduction in the force delivered with several shin guards reducing the force over 70 percent.

"Although it seems intuitive that soft compliant materials such as shin guards would reduce the force delivered, previous studies on softer baseballs have shown that this is not necessarily the case," said Dr. Janda. In some cases, softer materials used as protective devices actually increase the force delivered to a player."

Dr. Janda noted that like any other type of protective gear, the guards must be applied properly and worn during the play of the game to reduce the risk of injuries. He said that comfort and weight of the guard are important considerations in whether a player will wear a guard on the field. The lighter the guard, the easier it will be for the player to run, kick and compete in the play of the game. The weight of the guards tested varied from 2.0 to 6.5 ounces. Although the heavier guards lead to the greatest reduction in force delivered, some of the lighter guards approached them in protective ability.

Co-investigators included Cynthia Bir, M.S., R.N. and Stephen J. Cassatta, M.S.E.