Collagen quantification across human skeletal muscles

Intramuscular connective tissue provides structural stability and facilitates force transmission in skeletal muscle. Additionally, it contains extracellular matrix that is crucial for muscle development and regeneration¹. Alterations of collagen content within intramuscular connective tissue have been associated with aging or diseased muscle ²,³. Data of baseline collagen content among different muscles, to provide deeper understanding of normal muscular functions, does not exist. Hence the aim of the current study is to quantify collagen content across one hundred skeletal muscles in order to elucidate intrinsic specialized functional roles of skeletal muscles. Muscle biopsies were obtained from 6 fresh cadavers (n=599). Hydroxyproline assay was performed to determine collagen content⁴ in muscle samples measured in [mu]g of collagen per mg of muscle. Differences in mean collagen content were analyzed within muscle regions and by muscle functions. Additionally, previous muscle architectural data was used to examine the correlation between collagen content and muscle architectural properties ⁵⁻¹⁰. Results of the current study demonstrated significant differences in mean collagen content of muscles in different regions, but no correlation between collagen content and muscle architectural properties. Average collagen content was high in the body trunk and in the upper and lower extremities. Regions close to the trunk had low collagen content, and regions in between the trunk and extremities exhibited intermediate collagen conten