Muscle Strength and Changes in Physical Function in Women With Systemic Lupus Erythematosus

Abstract

Objective Cross-sectional studies have observed that muscle weakness is associated with worse physical function among women with systemic lupus erythematosus (SLE). The present study examines whether reduced upper and lower extremity muscle strength predict declines in function over time among adult women with SLE. Methods One hundred forty-six women from a longitudinal SLE cohort participated in the study. All measures were collected during in-person research visits approximately 2 years apart. Upper extremity muscle strength was assessed by grip strength. Lower extremity muscle strength was assessed by peak knee torque of extension and flexion. Physical function was assessed using the Short Physical Performance Battery (SPPB). Regression analyses modeled associations of baseline upper and lower extremity muscle strength with follow-up SPPB scores controlling for baseline SPPB, age, SLE duration, SLE disease activity (Systemic Lupus Activity Questionnaire [SLAQ]), physical activity level, prednisone use, body composition, and depression. Secondary analyses tested whether associations of baseline muscle strength with follow-up in SPPB scores differed between intervals of varying baseline muscle strength. Results Lower extremity muscle strength strongly predicted changes over 2 years in physical function even when controlling for covariates. The association of reduced lower extremity muscle strength with reduced future physical function was greatest among the weakest women. Conclusions Reduced lower extremity muscle strength predicted clinically significant declines in physical function, especially among the weakest women. Future studies should test whether therapies that promote preservation of lower extremity muscle strength may prevent declines in function among women with SLE.

Frailty and reduced physical function go hand in hand in adults with rheumatoid arthritis: a US observational cohort study

“…Further studies will need to directly examine the influence of disease activity on the relationship between frailty category and physical function in RA. Lastly, this observation corroborates prior studies that demonstrate the contribution of muscle weakness to reduced physical function among individuals with rheumatologic disease [15,16]. …”

“…Grip strength of the participant’s dominant hand was measured using a hand-held dynamometer [14]. In addition, lower extremity muscle strength was assessed using a Biodex® unit to measure peak isokinetic torque of knee extension as has been previously described [15,16]. For the primary analysis, grip strength cut points (adjusted for BMI and sex) from Fried et al [17,3] were used to define low grip strength.…”

Serum biomarkers of inflammation and muscle strength among women with systemic lupus erythematosus

“…Lower extremity muscle strength was assessed by peak isokinetic torques of knee extension and flexion as previously described (1). Maximum grip strength was measured using a hand-held dynamometer (1).…”

“…Maximum grip strength was measured using a hand-held dynamometer (1). Three trials, separated by rest intervals, were conducted for each hand.…”

“…Reduced muscle strength is strongly related to decreased physical function among women with systemic lupus erythematosus (SLE) (1, 2). Interleukin-6 (IL-6) mediates immune signaling pathways that influence skeletal muscle protein homeostasis and myogenesis (3).…”