Defense Date

2010

Document Type

Thesis

Degree Name

Master of Science

Department

Biomedical Engineering

First Advisor

Gerald Miller

Second Advisor

Peter Pidcoe

Abstract

Introduction: In gymnastics, athletes perform twisting and flipping skills at high angular velocities. These athletes rely heavily on sensory information from the visual, proprioceptive, and vestibular systems. The vestibulo-ocular reflex (VOR) is responsible for stabilizing the visual field on the retina during head movement. To accomplish this, the eyes are reflexively moved in a direction opposite the head. In a twisting gymnast, this actually reduces the ability of gymnasts to see the landing during airborne skills. Hence it becomes necessary for the gymnasts to cancel or suppress their VOR in order to view the landing. Objective: The purpose of this research is to investigate the relationship between gymnastics skill level and their ability to suppress the VOR. Methods: Ten female gymnasts (mean age 15±2.2) were obtained via a sample of convenience from a local club. The sample included both competitive and recreational gymnasts. Subjects were asked to wear a measurement system that could track head and eye movements as they performed a series of visual tasks. Three experiments were performed: (1) a saccadic experiment – two horizontally fixed LEDs (±10°) were alternately lit in a non-predictable pattern to provide visual cues, (2) a VOR experiment – the subject was asked to perform yawl head movements to an audible metronome beat 11 while visually fixating on an LED target 1m away, and (3) a vestibulo-ocular reflex suppression/cancellation (VORc) experiment – a laser pointer was fixed to the subject‟s helmet close to the cyclopean eye (slaving the target to the head movement) and the subject was again asked to perform head movements to a metronome while visually fixating on the target. In both VOR experiments, the metronome frequency varied from 72 to 196 beats per minute. Eye and head position data were synchronously sampled at 250 and 100Hz respectively. Data were post-processed using MATLAB. Periodic calibrations were performed throughout the experiment to test the continued reliability of the data. Results: Saccadic peak velocities and latencies were calculated for the sample population. Their performance did not differ from the normal population. VOR and VORc gains were also calculated and compared. The higher level (competitive) gymnasts were better at suppressing their VOR. In addition, left/right VOR gain asymmetries correlated highly with twist direction in seven of the competitive gymnasts. Discussion/Conclusions: There is a correlation between VOR performance and gymnastic level. These results do not suggest that VOR differences develop as a result of practice. These differences may simply allow some individuals to become better performers. A longitudinal study on a larger population would be required to test the causal relationship between these variables.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2010

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