Muscle endurance, strength, and active range of motion in patients with different subphenotypes in systemic sclerosis: a cross-sectional cohort study

Objective: Proximal muscle weakness is common in patients with systemic sclerosis (SSc). Dynamic muscle endurance, muscle strength in the lower extremities, and active range of motion (AROM) in the upper extremities are less studied. We investigated functional muscle endurance, strength, and AROM, and explored differences depending on skin and/or lung involvement in SSc patients.Method: The study divided 205 patients with limited/diffuse cutaneous systemic sclerosis (lcSSc/dcSSc) into no–mild and moderate–end-stage lung involvement, the latter based on the Medsger disease severity score. Dynamic muscle endurance in shoulder and hip flexion was assessed by the Functional Index-2, lower extremity muscle strength by the Timed-Stands Test (TST), and shoulder–arm AROM by the Functional Shoulder Assessment (FSA).Results: Shoulder and hip flexion muscle endurance were reduced in relation to reference values median (IQR) [53% (27–100%) and 40% (23–90%), respectively, p < 0.001]. Patients with moderate–end-stage l...