Handgrip Strength Relative to Estimated Skeletal Muscle Mass and Threshold-Defined Physical Performance in Biochemically Controlled Acromegaly: A Cross-Sectional Study

Background/Objectives: Muscle quantity, strength, and performance may not change in parallel in acromegaly. We compared absolute handgrip strength, estimated skeletal muscle mass (SMM), and handgrip strength relative to SMM (analyzed continuously) by threshold-defined gait and chair-stand impairment. Methods: This cross-sectional study of 76 adults with biochemically controlled acromegaly estimated SMM as 0.566 × bioimpedance-derived fat-free mass; gait (≤0.8 m/s) and chair-stand (>15 s) results were binary. Six full-cohort exact permutation comparisons (Holm-adjusted) formed the primary analysis. As no men met either threshold, a post hoc women-only sensitivity analysis was added. Results: Gait and chair-stand impairment occurred in four and three participants, respectively (five overall, all women with diabetes). In full-cohort comparisons, gait impairment was associated with lower absolute (Holm-adjusted p = 0.0035) and relative (p = 0.0061) handgrip strength, and chair-stand impairment with lower relative handgrip strength (p = 0.0012); estimated SMM did not differ clearly. In the women-only sensitivity analysis, median absolute and relative handgrip strength with versus without gait impairment were 26.65 vs. 32.15 kg and 0.918 vs. 1.142 kg/kg (both Holm-adjusted p = 0.0486). Median estimated SMM was numerically higher in women with chair-stand impairment (31.41 vs. 27.05 kg), so lower relative handgrip strength may partly reflect a larger denominator. In women with diabetes, no exploratory comparison remained below 0.05 after Holm adjustment. Conclusions: Lower relative handgrip strength accompanied impairment without a clear reduction in estimated SMM, but few events, all in women with diabetes, limit interpretation. These hypothesis-generating findings do not establish an acromegaly-specific muscle phenotype.