Report on the frontal and transverse plane range of motion of the hip during the "en dehors pirouette" in pre-profesional dancers.

Abstract

Introduction: Classical ballet standards portray ideal movements with little freedom of kinematic variance [1]. In regard of this complexity, some of the most common movements in ballet have been studied, including the plie´ , releve´ , passe´ , de´ gage´ , de´ veloppe´ , grand battement , turns or falls [2]. The pirouette and more specifically its en dehors form is established as the first turn a dancer should learn and its enhancement is essential to perform more complex techniques. Wrong technical execution repeated over time can cause injuries. Hip injuries can count up to 50% of the total of injuries a dancer can suffer and 20% of them are labral tears [3]. A good technical performance can help avoiding injuries and by knowing the correct values of movement we can detect and modify injurious patterns of movement. Research question: Which are the normality values of range of motion (ROM) of the hip during the swing phase of the en dehors pirouette for the frontal and transverse plane? Methods: 14 pre-professional dancers were recruited from dance conservatories in Madrid. The sample was formed with 2 male and 12 female dancers, with a mean age of 20.93 years (SD 1.774), mean height of 165.44 cm (SD 6.7), mean weight 56.71 kg (SD 7.65). BTS Smart D 300 motion capture system 240 Hz acquisition was used to acquire ROM from the hip and all data was processed using the smart analyzer tool of the system. A part of the Davis protocol was used to acquire the ROM data from the hip, markers were placed upon sacrum, ASIS, trochanters, thighs and condyles. Dancers realized a warm-up of 10 min and then were asked to perform 3 turns with each leg with a rest between series of 3 min. A mean of the 3 trials was made for each participant. Results: N = 14 Adduction+, abduction , external rotation+, internal rotation Minimum value Maximum value Mean Standard deviation Frontal plane ROM dominant limb as base 6.858 9.318 2.04868 4.99682 Frontal plane ROM non dominant limb as gesture leg 10.888 34.248 21.95878 7.13406 Frontal plane ROM non dominant limb as base 4.948 6.268 1.07228 3.58432 Frontal plane ROM dominant limb as gesture leg 8.418 41.638 21.57688 9.54553 Transverse plane ROM dominant limb as base 2.568 19.718 11.29718 5.08421 Transverse plane ROM non dominant limb as gesture leg 36.158 67.578 52.49168 7.99638 Transverse plane ROM non dominant limb as base 0.778 31.648 12.68608 8.40166 Transverse plane ROM dominant limb as gesture leg 36.388 69.688 52.19518 7.99638 Discussion: Normality values for the swing phase in its highest value of the pirouette en dehors were obtained for both legs, base leg and gestural leg, realized with the dominant limb and nondominant limb. Further research is needed and standard deviation values shall be used to make a proper sample size calculation in studies regarding the hip during this movement.

Introduction: Classical ballet standards portray ideal movements with little freedom of kinematic variance [1]. In regard of this complexity, some of the most common movements in ballet have been studied, including the plie´ , releve´ , passe´ , de´ gage´ , de´ veloppe´ , grand battement , turns or falls [2]. The pirouette and more specifically its en dehors form is established as the first turn a dancer should learn and its enhancement is essential to perform more complex techniques. Wrong technical execution repeated over time can cause injuries. Hip injuries can count up to 50% of the total of injuries a dancer can suffer and 20% of them are labral tears [3]. A good technical performance can help avoiding injuries and by knowing the correct values of movement we can detect and modify injurious patterns of movement. Research question: Which are the normality values of range of motion (ROM) of the hip during the swing phase of the en dehors pirouette for the frontal and transverse plane? Methods: 14 pre-professional dancers were recruited from dance conservatories in Madrid. The sample was formed with 2 male and 12 female dancers, with a mean age of 20.93 years (SD 1.774), mean height of 165.44 cm (SD 6.7), mean weight 56.71 kg (SD 7.65). BTS Smart D 300 motion capture system 240 Hz acquisition was used to acquire ROM from the hip and all data was processed using the smart analyzer tool of the system. A part of the Davis protocol was used to acquire the ROM data from the hip, markers were placed upon sacrum, ASIS, trochanters, thighs and condyles. Dancers realized a warm-up of 10 min and then were asked to perform 3 turns with each leg with a rest between series of 3 min. A mean of the 3 trials was made for each participant. Results: N = 14 Adduction+, abduction , external rotation+, internal rotation Minimum value Maximum value Mean Standard deviation Frontal plane ROM dominant limb as base 6.858 9.318 2.04868 4.99682 Frontal plane ROM non dominant limb as gesture leg 10.888 34.248 21.95878 7.13406 Frontal plane ROM non dominant limb as base 4.948 6.268 1.07228 3.58432 Frontal plane ROM dominant limb as gesture leg 8.418 41.638 21.57688 9.54553 Transverse plane ROM dominant limb as base 2.568 19.718 11.29718 5.08421 Transverse plane ROM non dominant limb as gesture leg 36.158 67.578 52.49168 7.99638 Transverse plane ROM non dominant limb as base 0.778 31.648 12.68608 8.40166 Transverse plane ROM dominant limb as gesture leg 36.388 69.688 52.19518 7.99638 Discussion: Normality values for the swing phase in its highest value of the pirouette en dehors were obtained for both legs, base leg and gestural leg, realized with the dominant limb and nondominant limb. Further research is needed and standard deviation values shall be used to make a proper sample size calculation in studies regarding the hip during this movement.