By Jordana Bieze Foster
Changes in landing mechanics that are intended to decrease risk of anterior cruciate ligament (ACL) injury may also inadvertently decrease jumping performance in athletes, according to research presented in late May at the annual ACSM meeting.
Researchers from multiple universities analyzed 18 male and 18 female athletes as they performed a stop-jump task under three landing conditions: normal landing, landing with increased knee flexion, and landing softly. The two latter techniques are often components of ACL injury prevention programs.
The investigators found that both techniques did indeed decrease peak ACL forces. However, both also had significant negative effects on approach speed, jump height, and stance time (which increased by 30% to 40%).
“Players whose priority is injury prevention can consider a soft landing or increasing knee flexion. However, for most competitive athletes, simply instructing them to land softly or increase knee flexion might have limited application in the real world,” said Boyi Dai, PhD, assistant professor of biomechanics at the University of Wyoming in Laramie, who presented the findings at the ACSM meeting.
Dai B, Garrett WE, Gross MT, et al. ACL loading and jump performance are decreased with increased knee flexion landing and soft landing. Presented at the 60th American College of Sports Medicine annual meeting, Indianapolis, May 2013.