The SLE group had significant differences from the sedentary control group in all the physiological measures except recovery heart rate. Test duration was 10.4 minutes for SLE vs. 13.1 minutes for healthy controls. Peak oxygen uptake was 23.2 ml/kg/minute for SLE vs. 29.6 ml/kg/minute for healthy controls. Maximum ventilation was 60.1 l/minute for SLE vs. 67.2 l/minute for healthy controls and peak respiratory exchange ratio was 1.13 for SLE vs. 1.17 for healthy controls. Maximum heart rate was 171 beats/minute for SLE vs. 182 beats/minute for healthy controls, and the predicted maximum heart rate was 94% for SLE vs. 99% for healthy controls. Maximal voluntary isometric contraction of the quadriceps was 298 N for SLE vs. 376 N for healthy controls. Resting lung function was notably worse: FEV 2.6 for SLE vs. 2.9 for healthy controls. Symptomatic measures were greater for SLE in the categories of total physical and mental fatigue. Fatigue severity score was 5.67 for SLE vs. 3.33 for healthy controls < 0.001. Depression score was 7 for SLE vs. 3 for healthy controls <0.001 and mental health score was 64 for SLE vs. 76 for healthy controls <0.001. The regression models for physical disabilities correlated with exercise duration (p<0.001) and the regression model for fatigue demonstrates that fatigue correlated with depression (p< 0.001).