VO₂ on-kinetics and aerobic exercise training in females with systemic lupus erythematosus

Fatigue among females with systemic lupus erythematosus (SLE) is commonly reported as the most debilitating symptom. Slower oxygen uptake (VO₂) on-kinetics have been observed among females with SLE, when compared to healthy control individuals. Aerobic exercise training may improve VO₂ on-kinetics, however, this has not been examined in the SLE population.ObjectiveTo characterize VO₂ on-kinetics in SLE and examine changes after 12 weeks of aerobic exercise training (AET).MethodsFemales (n = 16; 42 ± 10 years) with SLE (SELENA-SLEDAI ≤ 4) completed a cardiopulmonary exercise test (CPET) and a constant work rate test (CWRT), before and after participation in supervised vigorous treadmill AET for 12 weeks. Pulmonary gas exchange, heart rate (HR) and deoxygenation ([HHb]) of the right gastrocnemius muscle were also measured during the CWRT. Model fits for VO₂, HR and [HHb] were performed, and a ratio of the increase in [HHb] and VO₂ were examined in a subset of participants (n = 10). On-kinetic responses of all variables and the [HHb]/VO₂ ratio were analyzed before and after AET using paired sample t-tests or Wilcoxon signed-rank tests. Spearman's rank correlations were used to examine the relationships of VO₂ on-kinetics and peak CPET variables.ResultsVO₂ on-kinetics was faster (mean difference [95% CI], p-value: -12.0 s [-18.1 to -6.0], p < .001) following AET, and the VO₂ time constant post-AET was moderate and indirectly related to cardiorespiratory fitness outcomes for peak VO₂ (r_s = -0.562, p = .024) and peak work rate (r_s = -0.535, p = .033). The HR on-kinetics was also faster following AET (median difference [95% CI], p-value: -6.7 s [-30.8 to -1.2], p = .022), however a change in the [HHb] time course was unlikely (median difference [95% CI], p-value: -1.1 s [-3.6 to 23.5], p = .508).ConclusionFollowing supervised exercise training, females with SLE demonstrated faster VO₂ on-kinetics, which were also related to cardiorespiratory fitness. The faster VO₂ on-kinetics with exercise training was also accompanied by faster HR on-kinetics, suggesting central circulatory adaptation occurring in these females with SLE.