Knee coordination during landing in ballet-trained female dancers and non-dancers

Dance is a prevalent activity in females who are at a greater risk for traumatic knee injuries compared with males. However, dancers have a lower injury incidence than other athletes, and landing techniques obtained from training may limit accessory frontal plane movement. Frontal and sagittal plane kinematics, kinetics, and knee coordination patterns were compared between 18 ballet-trained female dancers and 18 non-dancers throughout the landing phase of a drop vertical jump. Dancers landed with greater peak knee flexion (-113.23 ± 15.1° vs. -99.3 ± 16.2°; p = 0.013, d = 0.890) and lower peak knee abduction (-1.15 ± 4.28° vs. -7.26 ± 6.26°; p = 0.002, d = 1.145) compared with controls. Dancers had smaller external knee flexion moments (0.14 ± 0.02 vs. 0.17 ± 0.05 BWxHt, p = 0.043, d = 0.702), smaller peak external knee abduction moments (0.024 ± 0.011 vs. 0.0036 ± 0.014 BWxHt, p = 0.046, d = 0.680), and smaller peak vertical ground reaction force (1.57 ± 0.22 vs. 1.92 ± 0.43 BW, p = 0.005, d = 1.008) compared with controls. Dancers also utilized a coordination pattern that included less in-phase motion (p < 0.001) between the sagittal and frontal knee coupling and more exclusive shank motion (p = 0.027) between the thigh and shank in the frontal plane compared with controls. There were no differences between the groups in exclusive sagittal plane (p = 0.386), exclusive frontal plane (p = 0.708), or anti-phase (p = 0.443) motion between the sagittal and frontal knee coupling compared with controls. Dancers undergo extensive landing training, which may contribute to less frontal plane knee motion. As such, dancers' ability to flex the knee without additional and simultaneous knee abduction during landing may help to mitigate their acute knee injury risk.