Poor muscle strength and function in physically inactive childhood-onset systemic lupus erythematosus despite very mild disease

Abstract

Objective: To compare muscle strength (i.e. lower- and upper-body strength) and function between physically inactive childhood-onset systemic lupus erythematosus patients (C-SLE) and healthy controls (CTRL). Methods: This was a cross-sectional study and the sample consisted of 19 C-SLE (age between 9 to 18 years) and 15 CTRL matched by age, sex, body mass index (BMI), and physical activity levels (assessed by accelerometry). Lower- and upper-body strength was assess by the one-repetition-maximum (1-RM) test. Isometric strength was assessed through a handgrip dynamometer. Muscle function was evaluated by the timed-stands test (TST) and the timed-up-and-go test (TUG). Results: When compared with CTRL, C-SLE showed lower leg-press and bench-press 1-RM (p = 0.026 and p = 0.008, respectively), and a tendency towards lower handgrip strength (p = 0.052). C-SLE showed lower TST scores (p = 0.036) and a tendency towards higher TUG scores (p = 0.070) when compared with CTRL. Conclusion: Physically inactive C-SLE patients with very mild disease showed reduced mus- cle strength and functionality when compared with healthy controls matched by physical activity levels. These findings suggest C-SLE patients may greatly suffer from a physically inactive lifestyle than healthy controls do. Moreover, some sub-clinical "residual" effect of the disease or its pharmacological treatment seems to affect C-SLE patients even with a well-controlled disease.