Kinematic Analysis of Swimmers with Permanent Physical Disabilities

Abstract

When the movement patterns of persons with permanent physical disabilities are observed from underwater, it is apparent that they have adapted unique variations in their swimming strokes to compensate for existing anatomic and neuromuscular deficits. Using underwater videotaping and subsequent analysis it is now possible to both identify and evaluate the movement mechanics of these swimmers. The purpose of this paper is to describe how motion analysis technology can be used in biomechanical research to examine the stroke mechanics of swimmers with permanent physical disabilities. In addition, we will identify the unique movement patterns of these swimmers, and, when applicable, discuss the limitations to their swimming efficiency. Aquatic exercise has been used extensively in the past 20 years as a rehabilitative and therapeutic modality for individuals with permanent physical disabilities. The freedom of movement in the water and the ability to exercise muscles which, on land, have difficulty overcoming gravitational constraints makes swimming and related aquatic activities invaluable for persons with a wide range of physically disabling conditions (Daly, 1999; Dummer, 1999; Prins, 1988). Since the primary intent of analyzing the swimming stroke mechanics of disabled swimmers is to improve instructional techniques, the first objective is to examine the underwater movement patterns of these swimmers. The methods for teaching and analyzing the swimming stroke mechanics of swimmers with permanent physical disabilities are similar to those used for assisting able-bodied swimmers. Stroke patterns are videotaped from above- and underwater and evaluated using digital video recorders. Slow motion and freeze-frame capabilities of the video recorders allow more detailed analysis; however, these assessments, no matter how detailed, remain somewhat subjective. With the advent of motion capture technology, which is used for research in biomechanics, it is now possible to determine motion more precisely by quantifying the results. Biomechanics is divided into two branches of study. Kinematics deals with the description of spatial and temporal parameters of movement measured as linear and angular displacements, velocities, and accelerations. Kinetics examines the forces that lead to the resulting kinematic changes (Griffiths, 2006; Kreighbaum, 1996). Using underwater videography and motion capture technology, the