Background Muscle strength and muscle mass are strong predictors of health, yet how these markers vary among individuals with long-term conditions (LTCs) is not well understood. This study aimed to compare muscle strength and muscle mass in individuals with various LTCs to those of healthy individuals, using data from the UK Biobank. Methods This cross-sectional study included 444,420 participants aged 37 to 73 years from the UK Biobank. Prevalent LTCs were self-reported at baseline, and 25 LTCs with a prevalence ≥1% were included in the current analysis. Multimorbidity was defined as a prevalent LTCs count ≥2. Muscle strength was assessed using a handgrip dynamometer, while muscle mass was measured as fat-free mass (FFM) using bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DXA), and magnetic resonance imaging (MRI), all expressed as a percentage of total body weight. Linear regression analyses were conducted to examine how muscle strength and muscle mass varied by LTCs and multimorbidity. Results The lowest muscle strength in men was observed in those with rheumatoid arthritis, type 2 diabetes, stroke, gout, and deep venous thrombosis, with differences ranging from 11.8% to 6.1%, lower than the reference group. In women, the lowest strength was seen in people with rheumatoid arthritis, gout, type 2 diabetes, coronary heart disease, and stroke, with differences between -11.8% and -6.5%. Muscle mass was lowest in men with type 2 diabetes, gout, coronary heart disease, hypertension, and high cholesterol (-4.7% to -3.1%) and in women with gout, type 2 diabetes, hiatus hernia, coronary heart disease, and hypertension (-6.4% to -4.1%). Similar trends were observed when muscle mass was measured with DXA (n=4,719) and MRI (n=22,901). Muscle strength and muscle mass were lower in people with more LTCs, with a dose-response relationship. Conclusions This study demonstrates that muscle strength and muscle mass were lower in people with multiple LTCs and for certain conditions. This highlights the need for targeted muscle related interventions in people with multiple LTCs, particularly those with type 2 diabetes, rheumatoid arthritis, gout, and coronary heart disease.
Guerrero‐Wyss et al. (2025) studied this question.