Effects of Dancer-Specific Biomechanics on Adolescent Ballet Dancers' Posture En Pointe and Factors Related to Pointe Readiness: A Cross-Sectional Study.

Abstract

Objective: There are no universally accepted requirements or uniform protocols to determine when dancers can safely commence dancing en pointe (shod relevé). The purpose of this study was to examine dancer-specific biomechanics of adolescent pointe dancers and explore factors that may help determine pointe readiness.

Methods: Dancers (n=26; median age 14 yrs [IQR=13-16]) were stratified into two groups based on the ability to stand on the pointe shoe box as per a plumb line (Group 1: on the box; Group 2: not on the box) during parallel, shod relevé. Measurements included unshod weight-bearing range of motion (ROM) of ankle plantarflexion (PF) and first metatarsophalangeal (MTP) extension and shod posture assessment during first position elevé (rising into relevé with turned out, straight legs). Qualisys 3D motion capture and AMTITM force plates recorded dancers performing 10-15 repetitions of first position elevé. Comparison of three kinematic and three kinetic variables aimed to describe group differences during unshod and shod conditions. Wilcoxon signed-rank test assumed no difference between groups with a Bonferroni correction (p<0.0083).

Results: During unshod parallel relevé, ROM was different between groups for first MTP extension (deg; MedGroup1: 90°, IQR 80°-90°; MedGroup 2: 70°, IQR: 70°-80°, p<0.0001) but no statistical difference in ankle PF (deg; p=0.0098). There were no differences in C7 displacement (m; p=0.5055), ankle PF moment (p=0.1484), or hip mediolateral and anteroposterior moments (p=0.8785 and 0.8785, respectively) during shod first position relevé, indicating that both groups tend to engage the same dominant muscle groups (trunk extensors, ankle dorsiflexors, hip flexors, and hip abductors) during elevé.

Conclusion: Dancers in Group 1 demonstrated greater first MTP extension during unshod relevé compared to dancers in Group 2. Weight-bearing ROM could be a valuable tool in predicting pointe readiness of adolescent ballet dancers.