In ballet, a single movement can be developed into multiple variations by changing factors such as direction or magnitude. Similarly, the Dance-Specific Graded Rehabilitation Program (DSGRP) is built on the progression of three factors: (1) movement (relevés, heel raises; explosive relevés EXrelevé, heel raises with the intention to jump but not actually jumping; and sautés, small jumps), (2) leg support (double-leg and single-leg), and (3) barre support (two hands, one hand, and no hands). However, these factors are yet to be fully analyzed biomechanically. This study aimed to investigate the influence of movement, leg support, and barre support on mechanical load and impact characteristics of a dance-specific heel raise to jump progression. Eighteen healthy dancers performed the stages of the progression in a semi-randomized order. Mechanical load was quantified by peak vertical ground reaction force (vGRF) and illustrated by weight-bearing profiles. Impact characteristics relating to force-time dynamics were quantified by the rate of force attenuation (RFA) during takeoff and the rate of force development (RFD) during landing. Linear mixed models assessed the significance and incremental contributions of each factor for peak vGRF, RFA, and RFD, while weight-bearing profiles were analyzed descriptively. Results revealed increasing load and impact characteristics with movement type and leg support, though negligible influence of barre support. Incre¬mental increases were quantified for the first time in a dance-specific context. Findings support the inclusion of EXrelevés as an intermediary movement between relevés and sautés. Barre support did not influence vertical kinetics, suggesting the need to explore its potential role in transverse plane stabilization. The reported increments suggest the following progression for optimal loading: double-leg relevés, double-leg EXrelevé, single-leg relevé, single-leg EXrelevé, double-leg sauté, and single-leg sauté. Incremental effects of observed factors inform optimal sequencing for training and rehabilitation progressions in dance.
Haber et al. (Sun,) studied this question.