GROUND REACTION FORCES IN BALLET: DIFFERENCES ACCORDING TO FOOTWEAR AND JUMP CONDITIONS

Abstract

The purpose of this investigation was: 1) to investigate the maximal ground reaction force (GRF) when ballet dancers land from two jump conditions in pointe shoes, flat technique shoes, and barefoot; and 2) to explore if particular pointe shoe characteristics (e.g. shoe age, shank style) have an effect on the GRF of these jump landings. Twenty-one healthy, female college ballet majors (19.28 ± 1.01 yrs; 167.45 ± 4.39 cm; 52.75 ± 3.43 kg) from an elite program volunteered for this study. Two jump conditions were studied, these included an assemblé jump (a jump from one foot to two feet) and a grand jeté jump (a large jump from one foot to the other foot.) Three shoe conditions were studied; these included barefoot, flat technique shoes, and pointe shoes. Each dancer performed three assemblé jumps in each shoe condition, and three grand jeté jumps in each shoe condition, landing onto a recessed force plate. Vertical jump height and horizontal jump distance were also analyzed through video recording and Dartfish Version 6 software (Dartfish, Alpharetta, Georgia, USA). Order of jump and shoe condition trials were counterbalanced. Peak GRF (N) was measured and recorded. The subjects also completed a health history questionnaire and a ballet shoe questionnaire. The health history questionnaire contained questions regarding general health status, activity, and previous injury history, and the shoe questionnaire included information concerning specifics of the pointe and flat technique shoes used. Means and standard deviations of GRF were calculated for each trial. Separate repeated measures analysis of variance were calculated for each dependent variable. Each had two within subjects factors: shoe type, at three levels; and jump type, at two levels. One-way analyses of variance were performed on the specific pointe shoe characteristic data. Tukey post hoc test was completed on significant findings. For all calculations, the alpha level was set at a priori of p<0.05. Results of the statistical analysis revealed no significant differences in GRF between the shoe conditions (F2,20=1.94, p=0.16, ηp2=0.08, power=0.32), however, we did find a difference in GRF between jump types (F1,20=5.85, p=0.02). Post-hoc testing revealed that the grand jeté jump condition produced significantly higher GRF than the assemblé jump condition (mean difference=239.28N, 95% CI=32.95N to 445.62N). Analysis of point shoe characteristics revealed that neither shoe age [Assemblé (F1,20=0.005, p=0.944); Grand Jeté (F1,20=1.908, p=0.183)] nor shank style [Assemblé (F1,20=0.058, p=0.812); Grand Jeté (F1,20=1.596, p=0.222)] had any impact on GRF in either jump condition. Results of this study indicate that GRF varies between ballet jumps, with the grand jeté jump having higher GRF values than the assemblé jump; however, it does not appear that shoe condition significantly affects GRF during functional ballet movements. Overall, the results of this study indicate that shoe conditions do not have a significant impact on a dancer’s ground reaction force.