Reactive signal complexity influences biomechanical variables associated with ACL loading risk

Area of Science:

• Biomechanics
• Sports Medicine
• Injury Prevention

Background:

• Anterior cruciate ligament (ACL) injuries are common in athletes due to reactive movements.
• Understanding how environmental complexity affects landing biomechanics is crucial for injury prevention.

Purpose of the Study:

• To investigate the influence of reactive signal complexity on biomechanical variables linked to ACL loading risk.
• To analyze pre-landing and early landing mechanics during cutting tasks under varying levels of environmental uncertainty.

Main Methods:

• Thirty-one recreational athletes performed single-leg side and cross-cutting tasks.
• Four conditions were tested: anticipated, simple unanticipated, and two complex unanticipated scenarios.
• Biomechanical variables including stance time, take-off velocity, knee flexion, and ground reaction forces were measured.

Main Results:

• Complex unanticipated conditions led to increased stance time and peak vertical/posterior ground forces.
• These conditions also resulted in slower take-off velocities and decreased minimal knee flexion.
• Cutting mechanics became similar across side and cross-cutting tasks under high uncertainty, indicating altered movement strategies.

Conclusions:

• Increased reactive signal complexity promotes more reactive movement patterns, potentially increasing ACL loading risk.
• Delayed responses under uncertainty compromise cutting performance and increase injury risk.
• Screening for ACL injury risk in complex situations and training anticipation skills are recommended.