Ascertain whether PCSA follows isometric scaling with body size

Ascertain the scaling relationship between physiological cross-sectional area and body size across sex and age groups in human lower-limb muscles, and determine whether isometric scaling (exponent 0.66) holds or must be revised.

Background

Common practice assumes or tests isometric scaling laws for PCSA when adjusting model parameters across individuals, but recent findings suggest that fiber length does not scale with body mass, implying that PCSA may also deviate from isometric scaling. The authors note that current experimental data are insufficient to establish a definitive scaling law.

Resolving the correct scaling of PCSA with body size—particularly across sex and age—would provide a principled basis for adjusting maximum isometric forces in musculoskeletal models and improve the demographic fidelity of simulations.