The Difference in Lower Limb Landing Kinematics Between Adolescent Dancers and Non-Dancers.

The high prevalence of lower limb overuse injuries among adolescent ballet dancers may be due in part to repetitive land- ings. This cross-sectional study compared how adolescent ballet dancers perform a drop-landing task in comparison to non-dancers in order to help understand injury mechanics. Fifteen adolescent female ballet dancers aged 11.9 ± 1.1 years and 17 non-dancers aged 10.9 ± 0.9 years each performed three single limb drop-landings from a 30 cm box. An 18-camera motion capture system (Vicon MX; Oxford Metrics, Oxford, UK; 250 Hz) and a force platform (Advanced Mechanical Technology Inc., Watertown, Massachusetts, USA; 2,000 Hz) were used to collect lower limb joint angles in all three planes of motion and peak vertical ground reaction forces during the landing phase. These variables were compared for the two sets of participants using independent samples t-tests (p < 0.01). While the dancers landed with greater sagittal plane range of motion, this appeared to provide no mechanical advantage with no reduction in ground reaction force. Rather, the increased sagittal range of motion was coupled with increased coronal and frontal plane motion. This may place dancers at increased risk of injury.

Differences in lower limb biomechanics between ballet dancers and non-dancers during functional landing tasks.

OBJECTIVES: To determine the differences in the lower limb landing biomechanics of adolescent ballet dancers compared to non-dancers when performing a hop and a stop jump task. DESIGN: Cross-sectional. SETTING: Laboratory. PARTICIPANTS: Thirteen adolescent female ballet dancers (11.8 ±â€¯1.1 years) and 17 non-dancers (10.9 ±â€¯0.8 years) performed hop and stop jump tasks. MAIN OUTCOME MEASURES: Vertical ground reaction force, and three-dimensional ankle, knee and hip joint angles and moments during the landing phase. RESULTS: Dancers displayed greater sagittal plane joint excursions during the hop and stop jump at the ankle (mean difference = 22.0°, P < 0.001, 14.8°, P < 0.001 respectively), knee (mean difference = 18.1°, P = 0.001, 9.8°, P = 0.002 respectively) and hip (stop jump task; mean difference = 8.3°, P = 0.008). Dancers displayed a larger hip extensor moment compared to non-dancers (P < 0.001) during the stop jump task only. Dancers also took longer to reach peak vGRF and jumped three times higher than non-dancers (P < 0.001) during the stop jump task. No difference in peak vGRF between groups was displayed for either task. CONCLUSIONS: Adolescent dancers demonstrate a transfer of landing technique to non-ballet specific tasks, reflective of the greater jump height and sagittal plane joint excursions. This landing strategy may be associated with the low rate of non-contact ACL injuries in female dancers.