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Exploratory Analysis of the Relationships between Aerobic Capacity and Self‐Reported Fatigue in Patients with Rheumatoid Arthritis, Polymyositis, and Chronic Fatigue Syndrome
Author(s) -
Weinstein Ali A.,
Drinkard Bart M.,
Diao Guoqing,
Furst Gloria,
Dale Janet K.,
Straus Stephen E.,
Gerber Lynn H.
Publication year - 2009
Publication title -
pmandr
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.617
H-Index - 66
eISSN - 1934-1563
pISSN - 1934-1482
DOI - 10.1016/j.pmrj.2009.04.007
Subject(s) - medicine , physical therapy , rheumatoid arthritis , vo2 max , chronic fatigue syndrome , aerobic capacity , aerobic exercise , polymyositis , heart rate , blood pressure
Objective To determine if self‐reported levels of physical activity and fatigue are related to peak oxygen uptake (VO 2peak ) and whether these relationships differ among the patient groups (rheumatoid arthritis [RA], polymyositis [PM], and chronic fatigue syndrome [CFS]). Design Correlational investigation. Setting Two ambulatory research clinics at the National Institutes of Health, Clinical Center, Bethesda, MD. Participants There were 9 patients with PM, 10 with RA, and 10 with CFS. All patients met case criteria for their respective diagnoses. Methods/Main Outcome Measurements VO 2peak during bicycle ergometry and self‐reported fatigability, fatigue, and physical activity. VO 2peak was used as the criterion measurement of physiological fatigue with which the self‐reported variables were compared. Results The Pearson r revealed that self‐reported physical activity correlated with VO 2peak ( r = 61, P = .01). However, fatigability and fatigue did not correlate with VO 2peak . Linear regression analysis was performed to assess the effects of diagnosis group, self‐reported activity level or fatigue, and their interaction. A trend in the data showed a distinctive relationship between fatigue/fatigability within the 3 groups. In addition, when controlling for group status, self‐reported activity predicted aerobic capacity as measured by VO 2peak . Conclusions This study confirms that patients with chronic, but stable RA, PM, or CFS are fatigued and have significantly decreased aerobic capacity. Self‐reports of physical activity predicted VO 2peak , and may be used as an indicator of activity‐based aerobic capacity. Self‐reports of fatigue, however, did not correlate with VO 2peak and hence are assessing something other than an index of aerobic capacity, and provide additional information about patients' perceptions, which will require further investigation.