Muscle contraction and relaxation described by tactile stiffness

We developed a tactile sensor system that measures the stiffness of objects (tactile stiffness) and used it to describe the time course of muscle cont raction and relaxation. We examined fatigue resistance of the latissimus do rsi muscle (LDM), which is preconditioned for cardiomyoplasty. Time to peak , ripple of LDM, and time constant were calculated from the time course of LDM contraction and relaxation as described by tactile stiffness. We compar ed conditioned and unconditioned LDMs using these 3 parameters. The time co urse can be described by tactile stiffness. Tactile stiffness fell exponent ially during LDM relaxation. In mean values, time to peak increased 230%, r ipple decreased 20%, and time constants increased 424%. Significant differe nces were shown in 3 parameters between conditioned and unconditioned LDMs (p < 0.05). Our tactile sensor system can describe the time course of LDM c ontraction and relaxation. Examining the difference in time courses, we mig ht detect the level of LDM preconditioning for cardiomyoplasty.