Improved VO₂ On-kinetics After Aerobic Exercise Training In Women With Systemic Lupus Erythematosus

BACKGROUND: Women with systemic lupus erythematosus (SLE) report fatigue as their single most debilitating symptom, with poor performance fatigability (a phenotype of fatigue defined as a decline in performance during physical activity) having also been observed among this population. Slower oxygen uptake (VO2) on-kinetics have been reported among women with SLE compared to a healthy control group, suggesting poor cardiorespiratory and oxidative metabolic response to an increase in energy demands contributing to fatigability in women with SLE. The effect of aerobic exercise training (AET) on VO2 on-kinetics has not been examined in patients with SLE. PURPOSE: To examine VO2 on-kinetics in women with SLE before and after aerobic exercise training (AET). METHODS: Sixteen women (age: 42 ± 10 years, BMI: 28.8 ± 5.5 kg/m2) with SLE (SELENA-SLEDAI <4) participated in supervised treadmill AET for 12 weeks at an intensity of 70 to 80% of heart rate reserve three times a week for 30 minutes. All subjects completed a series of constant workrate tests (CWRT) with gas exchange for determination of VO2 on-kinetics, before and after AET. VO2 was measured breath-by-breath and modeled using a mono-exponential equation. Subjects also performed a 10-minute walk test on a separate day for determination of the performance fatigability index as developed by Schnelle et al. Paired sample t-tests were used to compare the time constant of the VO2 on-kinetic response and the performance fatigability index, before and after AET. Pearson correlations were also used to examine the relationship between VO2 on-kinetics and the performance fatigability index. RESULTS: The time constant of VO2 was improved (p = 0.026) from baseline (32.97 ± 20.33 s) compared to after exercise training (20.41 ± 7.12 s). The performance fatigability index also improved significantly (p < 0.001) after AET. There was no significant relationship between changes in VO2 on-kinetics and the performance fatigability index with AET. CONCLUSION: While AET improved the oxidative metabolic response to an increase in energy demand (as measured by VO2 on-kinetics) and reduced performance fatigability, further investigation is needed to better understand the role of AET on fatigability in patients with SLE. Funding: NIH/IRP ZIA CL060096