The purposes of this investigation were to examine the reduction in variability when
muscle size is expressed relative to a functional group and its effect on improving
muscle force prediction. Fourteen subjects performed maximum voluntary contractions
(MVC) of elbow flexion and knee extension and had CT scans taken of the thigh and
upper arm. The variation of relative cross-sectional area (RCSA) was significantly
lower than CSA (p < 0.01). No significant differences were found between male and
female RCSAs. A method of predicting individual muscle forces based on an MVC and
RCSA is presented that reduced prediction errors to a third of those predicted on
the basis of CSA and a specific tension or stress value of muscle.
Cross-sectional area - muscle force prediction - CT scan - specific tension
