Stiffening effect of human tendons during strain controlled fatigue loading

Abstract

The goals of our study were to evaluate the biomechanical differences between five tendons and the changes in biomechanical properties caused by low cycle fatigue loading. Achilles, quadriceps, semitendinosus + gracilis (STG), tibialis anterior (TA) and the peroneus longus (PL) were harvested from 8 donors. The grafts were removed and placed in a radio-cryopro-tectant solution and slowly cooled and stored at -78 °C. The load was defined as a sinusoid function, the starting values are assigned to a peak load of 250 N and a minimum load of 0 N. Data was recorded in the 2th, 4th, 8th, 16th, 32nd, 64th, 128th, 256th, 515th and 1000th cycle. In the given cycles the whole measured waveform was registered. Young modulus of elasticity was calculated. To compare the biomechanical behavior of the different tendons the Young’s modulus values were evaluated in the 64th, 128th, 256th, 512th and 1000th cycles. While in case of PL and STG tendons the change is apperantly linear in the investigated range, in case of the Achilles, quadriceps and TA tendons there is a region where a significant change in modulus occurs.