Cut-off values for the muscle mass indices determined using DXA in healthy Polish adults - a comparison to EWGSOP2 recommendation.

Background: Muscle mass measurements are vital for predicting health outcomes and diagnosing muscle disorders. This study provides reference data for appendicular lean mass (ALM) and total lean mass (TLM) in healthy Polish adults with normal muscle strength and physical performance as per EWGSOP2 guidelines.

Methods: The study included healthy volunteers with normal muscle strength and functional status. Lean mass was measured using Hologic Horizon DXA. Mean values of TLM, ALM, fat-free mass (FFM), and indices (TLMI, ALMI, FFMI) were calculated for seven age groups (by decade). Cut-off points equivalent to T-scores of -1 and -2 standard deviations (SDs) below the young adult reference mean (ages 20-39) were determined.

Results: Data from 1,111 participants (328 men, 46.3 ± 20 years; 783 women, 43.7 ± 23 years) were analyzed. In young adults, mean ALM was 28.1 kg (men) and 17.2 kg (women), and ALMI was 8.6 kg/m² (men) and 6.1 kg/m² (women). Low muscle mass cut-off points (2 SDs below) were 18 kg and 10.9 kg (ALM) and 6 kg/m² and 4.3 kg/m² (ALMI) for men and women, respectively. Men exhibited significantly greater lean mass than women across all age groups (P < 0.001). Lean mass declined with age in both genders, following a nonlinear pattern, except for ALMI in men.

Conclusions: This study provides the first population-based reference values for ALM and TLM in healthy Polish adults aged 20-89 years, integrating criteria for normal muscle strength and physical performance.