Release and retention in Alpine ski bindings.

Six different designs of alpine ski bindings were semistatically tested in a MTS machine, and measurements of release forces were performed at the toe and at the heel, perpendicularly, and at 30 degrees backward and 30 degrees forward from the normal of the ski, respectively. In the conventional, two-part bindings examined, there was no difference between the forces acting in perpendicular and oblique planes. The release resistance in oblique directions was lower than the retention force perpendicularly to the ski in two binding designs with a spring-loaded, moveable toe unit (Besser, "Jack" prototype). A low release resistance obliquely forward is important for the prevention of injury to the lower extremity when a skier falls forward. On analysis of the injury-preventing properties of a release binding, consideration should also be paid to release resistance in oblique planes.