Abstract
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.
Objective
To characterize VO2 on-kinetics in SLE and examine changes after 12 weeks of aerobic exercise training (AET).
Methods
Females (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.
Results
VO2 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).
Conclusion
Following 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.
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