REDUCED MUSCLE UPTAKE OF OXYGEN DURING EXERCISE IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective, To assess the factors limiting aerobic exercise capacity in patients with systemic lupus erythematosus (SLE). Methods. The anaero bic threshold (AT) and O-2 pulse, i.e., V-O2/heart rate (HR), were mea sured in 21 patients with SLE without cardiopulmonary complications by the analysis of expired gas during incremental work load in exercise testing. The relationships between work rate (WR) and V-O2, HR and V-O 2/weight (Wt), and lupus activity index (LAI) and AT were analyzed. Re sults. The AT of the patients with SLE was significantly lower than fo r a control group. Little increase in O-2 pulse and very low Delta V-O 2/Delta WR and Delta V-O2/Wt Delta HR were found during work load in s ome patients with SLE, especially those with a low AT and high LAI. Pa tients with SLE with a high LAI tended to show a low AT. Conclusion. T he low aerobic exercise capacity of patients with SLE appeared to be m ainly due to a small increase in O-2 pulse. This may have resulted fro m impaired oxygen diffusion in the inflamed peripheral muscles in pati ents with active SLE. Low AT may explain in part why patients with SLE become easily fatigued.