The effects of fatigue and anticipation on the mechanics of the knee during cutting in female athletes

• The effects of fatigue and anticipation may not interact with one another.
• Both fatigue and anticipation independently alter the mechanics of the knee.
• Anterior cruciate ligament injury prevention programs may consider targeting these risk factors.
• Fatigue does not have a significant effect on reaction time.

BackgroundUnanticipated cutting tasks which do not allow for pre-planning of a movement have been reported to promote knee mechanics which may increase the risk of anterior cruciate ligament injury. Fatigue has also been reported to have similar effects. Athletes must often perform unanticipated tasks when they are fatigued. Previous studies have reported that the effects of anticipation become more prominent as an athlete progresses through a fatigue protocol. However, the protocols previously utilized may not mimic the demands of sports participation.MethodsThree-dimensional knee joint kinematics and kinetics were collected from 13 female athletes while they performed a run-and-cut task, before and after completion of an intermittent shuttle run. Trials were further divided (pre-planned, unanticipated) to assess the effects of anticipation.FindingsThere were no significant interactions between the effects of fatigue and anticipation for the peak knee angles or moments of the knee joint in any plane. Subjects did demonstrate a 68% increase in their peak knee abduction angles following completion of the intermittent shuttle run. Anticipation also had a significant effect on the mechanics of the knee in all planes. Most notably, there was a 23% increase in peak knee abduction angles and a 33% increase in the peak internal knee adduction moments.InterpretationBoth fatigue and anticipation promoted knee mechanics which are associated with an increased risk of knee injury. However, it does not appear that their effects combine when athletes are at a level of fatigue which is thought to reflect sports participation.