Knee joint biomechanics under external focus instructions promoting a quiet, safe and soft landing

Anterior cruciate ligament injuries are common in young female athletes, often occurring during landing tasks. Attentional focus instructions may influence landing biomechanics and reduce injury risk, but comparative effects of different external focus (EF) cues remain unclear.

Twelve novice female volleyball players (age: 13.6 ± 0.6 years) performed double-leg drop landings from a height of 50  cm under four attentional focus conditions: (1) as quietly as possible, (2) as safely as possible, (3) as softly as possible, and (4) a no-focus control. A Qualisys 3D motion capture system and a Kistler force platform were used to analyze knee joint kinematics and kinetics during initial contact and the first two VGRF peaks, and time-series analysis was conducted to characterize the biomechanical landing pattern across conditions.

All EF conditions significantly reduced biomechanical knee joint loading compared with the no-focus condition. Although no significant differences were found among the three EF instructions, the 'soft' landing instruction produced the most pronounced changes, showing the lowest maximal VGRF, increased knee flexion angles, and reduced internal rotation angles, relative to the no-focus condition.

EF instructions, particularly those emphasizing a soft landing, can effectively reduce knee joint loading and potentially lower anterior cruciate ligament injury risk in young female athletes. These findings highlight the value of incorporating specific attentional focus cues into injury prevention and training programs.