IADMS New York 2002   [back to the Category]

Smoothness During a Multi-Joint Movement: 2D and 3D Analysis Between Groups of Differing Skill Level   [read the french version]

Author :   Jonathan Spriggs, BE; Shaw Bronner, PT, & Al.

Smoothness During a Multi-Joint Movement:
2D and 3D Analysis Between Groups of Differing Skill Levels


Jonathan Spriggs, BE; Shaw Bronner, PT; Bruce Brownstein, PT; Sheyi Ojofeitimi, PT
SOAR Research, Long Island University
Brooklyn, New York, USA

Introduction: Variation in motion between groups of dancers using a commonly performed movement (arabesque) is investigated. A quantitative measurement of “smoothness” (Jerk or rate of change of acceleration) is employed in order to evaluate how the control of variables altered with increasing skill levels and learning. A Jerk Cost function is used for comparison across subject groups. Numerous studies have typically been limited to 2D analysis; due to the relative complexity of the arabesque however, in this study 3D analysis is further considered.

Methods: A Vicon 5 camera system with data acquisition software, sampling at 120 Hz, was employed to capture right toe marker displacement data from 30 male and female subjects (14m and 16f), age range 18-36 (22 mean) in the Global X,Y and Z coordinate system. The subjects were allocated to groups representing three distinct levels of training: Beginner, Advanced and Expert.

Results And Discussion

2D and 3D Jerk Cost was determined for the three distinct movement phases (passé (1), développé arabesque (2) and return (3)) of the arabesque. Figure 1 illustrates a typical arabesque right toe resultant displacement curve, with Figure 2 showing mean 3D Jerk Cost values for the three groups and each of the indicated phases. The mean phase 2D (x-y), (x-z), (y-z) (Frontal, Transverse and Sagittal planes respectively) and 3D Jerk Cost results obtained for the three groups show reduction in values from beginner to expert, implying increased “smoothness” within the motion phases of the arabesque movement. Ongoing analysis into the validity of this approach with comparison of 2D and 3D data is currently being studied.


Acknowledgment:
Supported by the Fan Fox and Leslie R. Samuels Foundation.