Relationship Between Achilles Tendon Mechanical Properties and Gastrocnemius Muscle Function

Strain was measured along the length of frog (Rana pipiens) gastrocnemius muscle-tendon units (MTU). Maximum muscle tension (P0) was measured, and the MTU was passively loaded to P0. Strain at P0 was measured at eight intervals along the tendon and aponeurosis and was approximately two percent for all regions except the aponeurosis region closest to the muscle fibers where it was about six percent. A computer model predicted sarcomere shortening of up to 0.5 micron due to tendon lengthening which demonstrates that tendons provide a more complex physiological function than simply transmitting muscle force to bones.