Effects of supervised aerobic exercise in patients with systemic lupus erythematosus: A pilot study
Article first published online: 7 APR 2005
Copyright © 2005 by the American College of Rheumatology
Arthritis Care & Research
Volume 53, Issue 2, pages 308–312, 15 April 2005
How to Cite
Clarke-Jenssen, A.-C., Fredriksen, P. M., Lilleby, V. and Mengshoel, A. M. (2005), Effects of supervised aerobic exercise in patients with systemic lupus erythematosus: A pilot study. Arthritis & Rheumatism, 53: 308–312. doi: 10.1002/art.21082
- Issue published online: 7 APR 2005
- Article first published online: 7 APR 2005
- Manuscript Accepted: 3 NOV 2004
- Manuscript Received: 19 JAN 2004
- Norwegian Foundation for Postgraduate Physiotherapists
It has been well documented that patients with rheumatoid arthritis (RA) can improve their strength and aerobic capacity through exercise, without exacerbating their symptoms or disease activity (1). Recent controlled studies also indicate that this is the case for patients with systemic lupus erythematosus (SLE), and that exercise might be followed by improvements in cardiovascular capacity and physical function (2–7). In these studies the outcome variables were assessed before and after a period of exercise. However, the question of whether exercise can induce disease flares and exacerbate symptoms during the exercise period, for instance at the start of the period, is clinically relevant and has not been investigated. The purpose of the present study was therefore to closely explore disease activity, symptoms, and physical function during a 3-month supervised aerobic exercise program and 3 months afterwards. The hypotheses were that aerobic exercise performed on a treadmill does not increase disease activity or symptoms at any time during an exercise period and that physical function would improve after exercise.
Materials and Methods
The patients were recruited from the outpatient clinic at Rikshospitalet University Hospital, Oslo, Norway. They were eligible for the study if they met the American College of Rheumatology classification criteria for SLE (8), were over the age of 18, and had no active disease in vital organs at the time of the study. Patients with a diastolic blood pressure >100 mm Hg, hemoglobin <7, and history of cerebral vascular accident or myocardial infarction were excluded.
Twenty-four patients with SLE who fulfilled the study criteria were invited by mail to participate. Six indicated that they were willing to take part in the study and were included after giving their informed consent in writing. All of them were women. Their mean age was 47 years (range 39–54 years) with mean disease duration of 16 years (range 2–34 years). Three patients worked full time and 3 had a disability pension. Two patients were performing regular exercise 2 or more times a week, and 4 reported no regular exercise.
The exercise program consisted of walking on a treadmill at an intensity of 70% of the patients' maximum heart rate as measured at exercise testing (9). To ensure the intensity, the heart rate was carefully controlled during all walking sessions. The patients walked at a comfortable self-selected speed (from 3.5–5.5 km/hour). The inclination of the treadmill was adjusted (from 0% to 2%) to achieve the desired heart rate. The exercise period increased gradually during the first 3-week period from 25 to 40 minutes, including 5 minutes for warming up and 5 minutes for cooling down. The program included 3 exercise sessions a week for a total of 12 weeks. The number of exercise sessions performed varied from 24 to 33 out of a possible 36 sessions.
Disease activity was assessed by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), which is a commonly used instrument for detecting changes in disease activity in patients with SLE (10). The SLEDAI assesses 24 descriptors including clinical and laboratory measures of SLE activity, and the score range is 0–105, with a higher score meaning higher disease activity. An increase >3 is considered to be a flare of the disease. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were also measured.
Pain and fatigue were assessed by the Medical Outcomes Study Short Form Health Survey (SF-36) pain and vitality subscores. The SF-36 is a generic health questionnaire and the pain and vitality subscores consist of items with a score range of 1–100, with the higher score indicating more vitality or less pain. The SF-36 has been tested on patients with SLE and found to be valid and reliable (11).
Aerobic capacity (maximum oxygen uptake [VO2max] and exercise time) was assessed by maximal exercise testing according to Naughton‘s protocol. This protocol, originally designed for patients with cardiovascular diseases, has been used in other exercise studies on patients with SLE (5) and found to be suitable for patients with possible joint involvement. According to this protocol, the workload is increased stepwise by increasing the inclination of the treadmill every other minute until it reaches 24%. The speed starts at 1.6 km/hour and increases to 3.2 km/hour after 2 minutes. To prevent ceiling effects, the speed was increased to 4.2 km/hour, which is still a walking speed, for the last 2 minutes of the test in this study. Expired gases were used to estimate VO2max. Exercise time was defined as the number of minutes the patients were able to walk before termination of the test.
Self-reported physical function was assessed by the SF-36 physical functioning subscore and the Modified Health Assessment Questionnaire (MHAQ). The SF-36 physical functioning subscore is designed to assess how a patient’s health affects everyday activities and mobility. The MHAQ is a disease-specific instrument designed for patients with rheumatic inflammatory diseases. It assesses patient mobility and their ability to perform activities of daily living. We used the 14-item version of the MHAQ to overcome floor effects (12). The MHAQ scores range from 1–4, with higher scores indicating greater dysfunction.
A single subject experimental design (SSED) was applied (13). The outcome variables were assessed every week for 3 weeks before starting the exercise program (baseline period); at 4, 8, and 12 weeks during the exercise program (treatment period); and 3 months after the exercise program had ended (followup). An important principle of the SSED is that the data in a period at baseline are compared with those in a period of treatment. Thus, the data at baseline are believed to indicate chance fluctuations in disease course, degree of affliction, and factors not related to treatment. The changes in data during treatment compared with baseline are ascribed to treatment effect. The study was approved by the Ethical Committee for Medical Research.
Visual analysis was applied to analyze changes during the exercise period for each individual, according to recommended guidelines (14). The analysis includes analysis of mean shift, trend, level, and overlap (analytic categories). Mean shift is the difference between mean of baseline compared with the mean of treatment period. Mean shift was positive when this difference was >0 and negative when the difference was <0. Trend is the direction of the curve and was registered as positive when at least the 2 last points of treatment pointed in a positive direction and negative when the opposite occurred. Level is the difference between the last assessment at baseline and the last assessment at treatment period. It was registered as positive when the difference between the last measurement in the intervention period and the last measurement in the baseline was >0. Overlap is the number of assessment points better than the range at baseline and was registered positive when at least 2 of the measurements in the intervention period were indicating improvement. Changes in at least 3 out of these 4 analytic categories were considered to reflect improvement/worsening. For the total patient group, the mean of the 3 assessments at baseline was compared with the last point of assessment at the treatment period and followup using Wilcoxon's signed rank test. The statistical significance level was set at 5%.
The analysis of the data from each individual patient showed no aggravation in disease activity as measured by the SLEDAI. Neither were there any clinically relevant changes in CRP and ESR. For the total group, no statistically significant changes were found in any variables (P > 0.1) at the end of the exercise period compared with baseline.
The data of each individual showed no aggravation in fatigue (Figure 1), pain (Figure 2), or physical function (Figure 3). Four patients experienced less fatigue after treatment (patients 2, 3, 4, and 5). Three patients improved their pain scores (patients 3, 4, and 6). Patients 1, 2, 5, and 6 improved their Vo2 max and patient 4 improved her exercise time. All patients but 1 improved in either MHAQ score (patients 1, 2, 4, and 6) or SF-36 physical function score (patients 1 and 3). For the total group, SF-36 vitality score was improved after exercise (P = 0.03) compared with baseline. The SF-36 physical function score differed from baseline after exercise (P = 0.03) and at followup (P = 0.03). VO2max differed from baseline after exercise and at followup (P = 0.05 and P = 0.03, respectively). No statistically significant changes were found in the SF-36 pain score (P = 0.1) and MHAQ score (P = 0.08) after exercise compared with baseline.
This study showed no individual aggravation of pain and disease activity during the exercise period. The improvements in fatigue and physical function showed some individual variation in effects, but significant improvements at group level are in line with the results of previous controlled group studies (2–7). Both the present study and previous studies have included patients with moderate to low disease activity. Hence, when considering the research findings at the present, one can only generalize the results to patients with low to moderate disease activity. The safety of exercise for patients with high disease activity, however, needs to be addressed in future studies.
The SF-36, MHAQ, and aerobic capacity have all been used as outcome measurements in previous exercise studies in patients with SLE and RA, and are believed to be relevant outcome measurements. In the present study, both the analysis of the individuals and the group showed significant improvements in aerobic capacity. With respect to the SF-36 functioning scores and the MHAQ scores, the individual and group analysis did not correspond. This might be due to different scaling of the instruments. The variations in data seen at baseline, however, indicate that there can be problems with the reliability of the measurement tools and the variation in the patients' situations. In studies with small sample sizes this can threaten the study validity. In the present study, we assume to control for such errors in the analysis of the individuals as the effects from exercise should be greater than the variation shown at baseline. However, a longer baseline period with more points of assessments had been desirable for making such an assumption. Another question is whether the small changes seen on the outcome variables are great enough to be clinically relevant. All patients stated that they had become better. Whether this is reflected by the results of the instruments is uncertain.
The small number of patients in the present study is a limitation for generalization. The sample size is an absolute minimum for statistical analysis and the risk of type II errors is great. Our results at group level, however, are in line with those reported in other controlled studies. Furthermore, no individuals showed aggravation at any point of assessment during the exercise period. The consistency between the results of the individuals indicates that the results are likely to be valid for other patients with low to moderate disease activity. Hence, it is reason to believe that exercise should be recommended for improving physical function. An important aspect of being physically active is to prevent cardiovascular diseases and osteoporosis found to be associated with SLE (15).
The present study shows that aerobic exercise does not aggravate disease activity at any time during an exercise period and can have some beneficial effects on fatigue and physical function in patients with SLE with low disease activity.
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