Pointing the foot without sickling: an examination of ankle movement during jumping.
The sauté is a relatively simple dance jump that can be performed by both highly skilled dancers and non-dancers. However, there are characteristics of jumping unique to trained dancers, especially in terms of foot and ankle movement during flight. Dancers are trained not to "sickle, " or to avoid the anatomically coupled ankle inversion that occurs with plantar flexion, maintaining the appearance of a straight line through the lower leg and foot. The purpose of this study was to examine ankle movements in elite dancers compared to non-dancers. Twenty healthy females, 10 with no prior dance training and 10 professional dancers, performed 20 consecutive sautés while three-dimensional kinematic data were collected. Sagittal and frontal plane kinematics were calculated and vector coding methods were used to quantify coordination patterns within the ankle in the sagittal and frontal planes. This pattern was chosen for analysis to identify the avoidance of a sickled foot by trained dancers. Peak ankle positions and coordination patterns between groups were examined using independent t-tests (a <0.05). Dancers demonstrated greater peak plantar flexion (p<0.01) and less change in ankle angle during the flight phase (p= 0.01), signifying holding the pointed foot position during flight. There was no statistically significant difference in sagittal and frontal plane ankle coupling (p= 0.15); however, the Cohen's d effect size for the difference in coupling was medium-to-large (0.73). Dynamic analysis of the foot and ankle during jumping demonstrates how elite dancers achieve the aesthetic requirements of dance technique.
Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 East Alcazar Street, CHP-155, Los Angeles, CA 90089, USA. Tel 323-442-2089, fax 323-442-1515. dnjarvis@usc.edu.
Danielle N
DN
Jarvis
Kornelia
K
Kulig
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology; D016022:Case-Control Studies; D003615:Dancing / Q000502:physiology*; D005260:Female; D006801:Humans; D009068:Movement / Q000502:physiology*