PURPOSE: The purposes of this study were to: 1) describe the magnitude and dimensions of self-reported fatigue in individuals with knee OA and 2) determine the influence of quadriceps fatigue and cardiorespiratory endurance on self-reported fatigue in individuals with knee OA, after accounting for potential confounders such as age, sex, pain, depression, and anxiety. SUBJECTS: The sample consisted of 44 adults (75% female) with radiographically confirmed knee OA. METHODS: All subjects participated in two testing sessions using a dynamometer with a software program developed specifically for this study. During the first session, subjects completed the Multidimensional Assessment of Fatigue Scale (MAF), the WOMAC Osteoarthritis Index, the Center for Epidemiologic Studies Depression Scale (CES-D), and the Beck Anxiety Inventory Scale (BAI). A burst superimposition maximum isometric quadriceps torque test was performed to determine maximum voluntary isometric contraction (MVIC) torque that was used in the quadriceps fatigue test. In the first testing session, subjects also performed a submaximal cycle ergometer test to estimate VO2 max as a measure of cardiorespiratory endurance. Within 1 week of the first session, subjects returned for the quadriceps fatigue test in which they performed repeated submaximal contractions equal to 50% of their MVIC isometric torque output for 6 seconds followed by a 4-second rest period (duty cycle 60%). The contractions were continued until the subject could no longer generate the torque target for 3 successive contractions. During the sixth contraction and every minute thereafter, subjects were instructed to push with a maximum effort and the train of electrical stimuli was superimposed upon the maximal effort quadriceps contraction. Quadriceps fatigue was measured as the rate of decline of the MVIC torque output over the course of the test. ANALYSIS: Descriptive statistics were used to describe the magnitude and dimensions of fatigue. An independent samples t-test was used to compare fatigue in individuals with knee OA to the levels of fatigue reported by normal controls and individuals with rheumatoid arthritis. Hierarchical regression analysis was used to determine the influence of quadriceps fatigue and cardiorespiratory endurance self-reported fatigue. RESULTS: The mean global fatigue index score was 23.6 (SD = 10.4, range 1-40). Individuals with knee OA reported significantly higher fatigue than controls and significantly lower fatigue than RA patients (p < 0.05). Fatigue was reported to occur every day by 25% of the sample. Fatigue most often affected walking, doing household chores, shopping, and exercise. Fatigue was significantly associated with sex (r = .52, greater fatigue in females), pain (r = .62), depression (r = .47), anxiety (r = .54), and cardiorespiratory endurance (r = -.55) but not to quadriceps fatigue (r= .01). Hierarchical regression analyses revealed that adding quadriceps fatigue or cardiorespiratory endurance to the model after controlling for age, sex, pain, depression, and anxiety did not explain any additional variance in fatigue, (ÄR2 =.00). CONCLUSION: Fatigue is common in individuals with knee OA. Quadriceps fatigue is not related to self-reported fatigue. Cardiorespiratory endurance is related to self-reported fatigue, but not after controlling for age, sex, pain, depression, and anxiety. CLINICAL RELEVANCE: Management of fatigue in individuals with knee OA may require interventions to address psychosocial issues and/or cardiorespiratory endurance.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-11122003-135008 |
| Date | 17 November 2003 |
| Creators | Bouzubar, Fawzi |
| Contributors | G. Kelley Fitzgerald, James J. Irrgang, Carol E. Baker, Anthony Delitto |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-11122003-135008/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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