Purpose. This study aimed to verify the reliability of estimating ballet dancers' postural stability during the unshod and the en pointe relev & eacute; position with a smartphone application Methods. The participants (13 ballet dancers, 22.4 +/- 2.5 years of age) were tested in the unshod and the en pointe relev & eacute; position (YMED Balance Test application, smartphone secured at the L5 level for centre of mass approximation, 10 trials for each condition, 10 seconds per trial, 2 -minute intertrial break, arms relaxed at bodyside, gaze fixated at an eye -level target, preferred feet width and orientation). Paired t -tests examined the inter -condition differences. Relative (intraclass correlation coefficient, ICC) and absolute (standard error of measurement, SEM, SEM%) reliability indices (for accumulated and paired trials) were computed for each condition (SPSS software v. 26.0, p < 0.05). Results. The total balance score and all centre of mass spatial measures indicated worse postural stability in the en pointe condition (p < 0.05), with no significant temporal differences (p > 0.05). The total body balance score was the most reliable measure (good to excellent ICCs, low to moderate SEM%) with a minimum of 8 trials ensuring reliability in both the unshod and the en pointe relev & eacute; positions. Conclusions. Taken a minimum of 8 trials and the measure of total balance score, we may obtain a reliable estimation of ballet dancers' postural stability in the unshod and the en pointe relev & eacute; position by using the YMED Balance Test smartphone application.
