Effect of strain rates on mechanical response of whole muscle bundle

Abstract

Muscle injury, especially hamstring muscle, frequently happens during sports activities and exercise which could have serious consequences if not diagnosed and treated promptly. This research investigated the quasi-static and dynamic responses of over 30 fresh semitendinosus muscle-tendon-bone structures by utilizing Split Hopkinson Pressure Bars (SHPB) and a material testing system under the strain rates between 0.001 ~ 200 s− 1. Because of the special shape of muscle-tendon-bone structures, PLA-material clampers were produced by 3D printer to properly hold and to prevent slippery during the test process. The mechanical characteristics of the whole muscle bundle, including Young’s modulus and stress-strain curve, are illustrated at various strain rates. The findings showed that the muscle properties were sensitive with strain rate at the passive deformation. Both maximum stress and Young’s modulus increased with the rise of strain rate, and modulus at 200 s− 1 can be as high as 10 times compared with quasi-static conditions.