Simple verbal instruction improves knee biomechanics during landing in female athletes

Knee injuries are highly prevalent in athletic populations, particularly among female athletes. Many of these injuries occur during landing from a jump. Various comprehensive knee injury prevention programs have been developed to date. However, there is a need to determine which components of these programs contribute directly to changes in knee biomechanics. Therefore, the purpose of this study was to investigate the immediate effect of three different simple verbal instructions on knee biomechanics during landing in adult female recreational athletes. Three-dimensional kinematic and kinetic analysis of landing from a countermovement jump was conducted in a counterbalanced cross-over repeated measures design. Results indicated that the instruction to land with equal weight distribution reduced the asymmetry of peak vertical ground reaction force compared to the control condition. The instruction to land softly reduced peak vertical ground reaction force and increased peak knee flexion compared to the control condition. The instruction to land with knees over toes increased peak knee flexion compared to the control condition. These findings indicate that verbal instruction may be a key component of the effects seen in previous research studies that have investigated the benefits of more complex training programs designed to reduce knee injury risk in female athletes.