Tibial torque generation in a flexed weight-bearing stance

Area of Science:

• Biomechanics
• Sports Medicine
• Orthopedics

Background:

• Understanding lower extremity torque is crucial for injury prevention and equipment safety.
• Ski binding release mechanisms are designed based on expected torque forces.

Purpose of the Study:

• To quantify internal and external lower extremity torque generation in male subjects.
• To investigate the influence of knee flexion, footwear, and torso movement on torque output.
• To assess the implications of these findings for ski binding release standards.

Main Methods:

• 18 male subjects performed maximal twisting efforts against an instrumented torque cell.
• Torque was measured under various conditions: seated vs. single-leg stance, different knee flexion angles, athletic shoe vs. ski boot, and restrained vs. unrestrained torso movement.
• Internal and external torques were compared under different movement conditions.

Main Results:

• Mean torque values ranged from 30 to 71 Nm.
• Torque was significantly higher during flexed single-leg stance (19-49%), with 45° knee flexion (11-16%), and in ski boots (8-11%).
• Allowing torso movement increased torque by 17-49%; internal torque was 12% greater than external torque when the torso was unrestrained.

Conclusions:

• Torque generation is significantly influenced by knee position, footwear, and upper body involvement.
• Achieving ski binding release may require combined torso/pelvic movement and a "locked knee" position, rather than isolated ankle twisting.
• Current ski binding release settings (ASTM standards) may necessitate these combined movements for effective release.