(2) JUMP LANDING DECELERATION: ESTABLISHING NORMATIVE RANGES FOR MALE AND FEMALE ATHLETES

Lower extremity joint (LE) kinematics during landing tasks are important predictors of injury risk and performance outcomes in athletes. The drop-jump landing task is a commonly employed method of injury screening in athletes and return to sport testing batteries. Normative ranges for LE kinematics have not been established in athlete or general populations. The identification of normative ranges for LE kinematics during landing tasks in a large cohort of healthy individuals can inform the development of performance optimization, rehabilitation, and injury prevention programs.

Purpose: The purpose of this study was to establish sex-related normative ranges for LE kinematics during the drop-jump task in a large cohort of healthy military cadets.

Methods: 5514 healthy military cadets (3371 males and 2143 females; age: 18.8 ± 0.9; BMI: 23.8 ± 2.9) participated in this study. Dominant limb kinematics were collected using an electromagnetic motion analysis system during the drop-jump task, sampling at 144 Hz. The drop-jump task consisted of participants jumping from a 30-cm high box set at a distance of 50% of their height, down to a force platform. Immediately after landing , they jumped vertically for maximum height. Force plate data was collected synchronously with the kinematic data at a sampling rate of 1440 Hz. Initial ground contact was defined as the point when the vertical ground reaction force exceeded 10 N upon landing. Sex-related differences in LE kinematics were analyzed using independent samples t-tests. Mean differences (MD) were reported for interpretability. Normative ranges were established for each joint angle in males and females separately at the initial contact and peak joint angles during stance (initial contact until takeoff).

Results: Compared to males, females exhibited reduced knee flexion (MD: -4.1˚, p < 0.001) and hip flexion (MD: -4.5˚, p < 0.001) angles but, greater knee valgus (MD: 3.3˚, p < 0.001) and hip adduction (MD: 1.7˚, p < 0.001) angles for both initial contact and peak angle. Interpercentile ranges are provided in Table 1 for normative reference.

Conclusions: This study provides normative ranges for LE kinematics during the drop-jump task in a large cohort of healthy military cadets. Sex-related differences in LE kinematics were observed, highlighting the importance of considering sex as a factor in the evaluation and management of lower extremity injury risk.

PRACTICAL APPLICATION:  The normative ranges for LE kinematics during the drop-jump task established in this study can be used by practitioners and researchers to identify those displaying aberrant movement patterns. These normative ranges may also aid in developing targeted programs to reduce injury and improve performance outcomes in male and female athletes.


Acknowledgements: None