Date of Graduation

2003

Document Type

Thesis

Degree Type

MS

Committee Chair

Michelle A. Sandrey

Abstract

Context: The effects of fatigue on joint position sense have been documented in the shoulder, knee, and lower extremity. In many research studies the authors have suggested that there is a decrease in absolute error in joint position sense after fatigue. However, the literature is scarce when it comes to the effects of fatiguing the plantar flexors on joint position sense. Objective: The purpose of this study was to determine fatigue of the gastrocnemius through a dynamic fatiguing protocol on joint position sense in dorsiflexion and plantar flexion of the ankle. Design: A 2 x 2 factorial design was used for this study. There were two independent variables with two levels each: condition (non-fatigued and fatigued) and measurement (10º of dorsiflexion and 20º of plantar flexion). The dependent variable was absolute error measurement. Setting: The study took place at West Virginia University at the Athletic Training Research Laboratory. Patients or other participants: Twenty healthy college students volunteered for the study. Subjects meeting any of the following exclusion criteria were excluded from the study: (1) prior history of multiple ankle sprains (three or more significant sprains within the past year), (2) an ankle sprain or ankle injury within the last six months, (3) any knee or ankle surgery within the past year, (4) any neurological or central nervous system deficits (5) taking any medication which may affect the nervous system. Interventions: The subjects that were selected were tested in the non-fatigued and fatigued condition on a custom built joint position sense device for the lower extremity. Subjects were blindfolded, and fit with earphones to eliminate any visual or auditory cues. The subjects were placed in the supine position with their dominant foot strapped into the device with elastic foam straps in order to eliminate any feedback from cutaneous receptors. The subjects underwent an active angle reproduction test at 10º of dorsiflexion and 20º of plantar flexion. Immediately following the testing in the non-fatigued position the subjects underwent a dynamic fatiguing protocol for the plantar flexors. The protocol involved subjects standing on their tip toes of both feet until they could no longer hold such as posture. Immediately following fatigue the subjects were tested in the fatigued condition. Main Outcome Measures: The researchers expected that there would be a significant difference in absolute error between the non-fatigued and fatigued condition at both 10º of dorsiflexion and 20º of plantar flexion. Results: There was no significant main effect for condition (F 1,19=2.412, P=.137) or for measurement (F 1,19=2.553, P=.127) Additionally, there was no significant interaction between condition and measurement (F 1,19=1.077, P=.312) Conclusion: The results of this study indicated that there was no significant difference between non-fatigued and fatigued conditions at 10º of dorsiflexion and 20º of plantar flexion measurements. Therefore, the main controller of conscious joint position sense of the lower extremity may be the tibialis anterior. Further research is needed in this area.

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