Kinematics of the Lumbar Spine During Classic Ballet Postures
Postural characteristics and three-dimensional (3D) kinematics of the lumbar spine were examined during classic ballet gestures in 25 expert dancers (17 females, 8 males; mean age, 21 ± 4 yrs). The 3D displacements of the thorax to the pelvis were sampled with a 3D-electrogoniometer during right and left arabesque, developpe a la seconde, and pied-en-main, and a photographic technique was used to calculate lower-limb elevation, shoulder inclination, and tragus or C7 displacement. The incidence of low-back (43%) and hip pain (40%) was large. Arabesque was characterized by lumbar extension (20-25°), ipsilateral bending (˜20°), and contralateral rotation (˜10°), and a 90° angle between the thighs. During pied-enmain and developpe a la seconde, lumbar flexion (˜30°), ipsilateral bending (10–15°), and contralateral rotation (˜20°) occurred. The angle between the thighs was 150° and 120°, respectively. There was poor correlation between medical history, anthropometrical characteristics, and postural and kinematics variables, except for shoulder inclination, which differed significantly between dancers with hip or low-back problems and those without complaints. We conclude that no relationship exists between hip flexibility and the lumbar spine contribution to various ballet tasks, suggesting that lower-limb elevation during arabesque and developpe a la seconde depends more on hip flexibility than on a lumbar contribution.