Ballet-Trained Individuals Demonstrate Reduced Postural Sway and Less Variation of Spinopelvic Kinematics Compared with an Age-Matched Untrained Group During Demi-Pointe Standing.

OBJECTIVE: The aesthetic demands require adaptations in posture that serve both functional efficiency and artistic purposes, but the relationship between spinopelvic alignment and center of pressure (COP) displacement in ballet dancers is understudied. Exploring the differences in these parameters between ballet-trained and untrained individuals could help determine whether the posture of dancers, adapted to aesthetic demands, is also efficient from a kinematic perspective. In this study, we compared postural sway characteristics and segmental kinematics between ballet dancers and non-dancers during three different standing positions with progressively increasing heel elevation (normal, 1/4 pointe, and demi-pointe). Additionally, this study sought to clarify the relationship between the spinopelvic and lower limb kinematics and the oscillations in the COP of the body.

METHODS: This study was designed as a comparative cross-sectional study. The study involved 11 ballet dancers and 10 nondancers. Variables such as COP path length, mean angular position, and coefficient of variance (CV) of the spinal-pelvis system (midthoracic, thoracolumbar, and lumbopelvic regions) and lower limb joints (hip, knee, and ankle) were measured. For variables with normal distribution, a two-way repeated-measures ANOVA was conducted to detect group and task effects, with post-hoc Tukey's HSD tests for significant interactions. Additionally, the relationships among COP path length, angular position, and CV were analyzed using correlation coefficients.

RESULTS: Dancers demonstrated significantly shorter COP path length in demi-pointe (701.3 vs 902.2 mm, p<0.05) and greater ankle plantar flexion in both elevated positions (1/4 pointe: -13.3° vs -7.2°, p<0.05; demi-pointe: -44.7° vs -22.5°, p<0.01) compared to nondancers. With increasing heel height, the number of segments showing a significantly higher CV compared with normal standing increased in both groups. In the demi-pointe posture, dancers exhibited a correlation between COP path length and hip and knee angles (p<0.05) and nondancers showed correlations between COP path length and CV of the midthoracic (p<0.01), thoracolumbar (p<0.05), knee (p<0.01), and ankle (p<0.01).

CONCLUSION: Dancers exhibited better balance, as indicated by a shorter COP path, particularly in the demi-pointe position, compared to nondancers. While no significant differences were found in spinopelvic kinematics between groups, these were associated with COP path length in nondancers during demi-pointe owing to within-group variations, unlike in dancers.