| Summary: | Objective: The primary aim of this study was to investigate interseason variability in the knee frontal plane projection angle (FPPA) at the impact phase of a single-leg dropjump test in female and male professional ballet dancers. The secondary aim was to explore the effect of leg dominance and ankle dorsiflexion mobility on the FPPA.
Methods: Twenty-six professional ballet dancers (females n=14, males n=12) performed single-leg vertical drop jump tests at the beginning of the 2019-2022 seasons. FPPA was measured from the most profound knee angle of the impact phase of the single-leg drop jump. Self-determined leg dominance and a knee-to-wall test were used to measure other variables.
Results: Mean values for the knee FPPA varied from 0.3° to 3.1° in the right and from 1.2° to 2.6° in the left leg in female ballet dancers during the three study years. In male ballet dancers, the corresponding values were from 1.3° to 3.1° on the right and -3.9° to -3.1° on the left leg. There was a statistical difference in the FPPA of the left leg between females and males (p<0.01).
No intra-individual differences in FPPA were observed between the three study years. Also, no statistical difference was found in the change of FPPA values between males and females in the study years. When comparing dominant and non-dominant legs, there were no statistically significant differences in the FPPA between the legs and the study years. A correlation between increased knee valgus and decreased ankle ROM was found in this study in the dominant leg (-0.356) and in the non-dominant leg (-0.379) (p<0.01).
Conclusion: To our knowledge, this is the first study on the interseason variability of landing biomechanics in professional ballet dancers, showing no statistically significant differences between study years. This study indicated minor differences between female and male dancers' knee valgus position during the impact phase of a drop jump, and in knee control between dominant and non-dominant legs. The effect of ankle dorsiflexion mobility on knee control was confirmed with professional ballet dancers. This study
provides more profound information on female and male dancers' biomechanics, which has not been investigated widely.
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