Use of tactile stiffness to detect fatigue in the latissimus dorsi muscle

In clinical settings, no method has been established to examine the fatigue of a latissimus dorsi muscle (LDM) preconditioned for cardiomyoplasty. We examined the feasibility of measuring muscle stiffness (tactile stiffness) to evaluate muscle fatigue in situ using our tactile sensor. We stimulated canine LDM with burst pacing and monitored both stiffness and tension to de termine their relationship. In both dissected LDM and LDM in situ, the decr ements of these parameters during burst pacing were compared between precon ditioned and unconditioned LDM. In measurement in situ, the sensor probe wa s placed on the LDM through a small incision. Strong statistical correlatio n was shown between stiffness and tension (r = 0.935). In decrements of sti ffness in situ, there were statistically significant differences between pr econditioned and unconditioned LDM. Our tactile sensor system can provide a n efficient method for evaluating fatigue of muscles in situ without measur ing muscle tension.