The reliability of an aerobic and an anaerobic exercise tolerance test in patients with juvenile onset dermatomyositis

OBJECTIVE: To investigate the reliability of an aerobic and an anaerobic exercise test in patients with juvenile dermatomyositis (JDM). METHODS: Sixteen patients with JDM (mean age 13.85 +/- 6.4 yrs, range 6.7-27.2) participated. Anaerobic exercise capacity was measured using the Wingate Anaerobic Exercise Test (WAnT). Aerobic exercise test was performed using a graded exercise test to volitional exhaustion on an electronically braked cycle ergometer. Patients were tested and retested within 12.8 +/- 5.7 days. RESULTS: Correlation coefficients and other reliability statistics indicated that peak power and mean power on the WAnT and peak oxygen uptake (VO2peak) and maximal workload (Wmax) on the aerobic exercise test could be reliably assessed in patients with JDM. Pearson (R) and intraclass correlation coefficients (ICC) were > 0.85, and typical error was < 20% for the peak power and mean power on the WAnT. On the aerobic exercise test the R and ICC were > 0.95, and typical error was < 6% for the VO2peak and Wmax. CONCLUSION: We found acceptable reliability for the WAnT and very good reliability for the aerobic exercise test. This indicated that these exercise tests could be performed reliably in patients with JDM.