抄録
Many people are suffering from muscle pain, but research for its mechanism is lacking. One reason for this is absence of appropriate methods to evaluate it. One conventional method to measure muscle pain in an awake subject is to apply pressure through the skin. Its inevitable complication is to affect the skin thus may cause undesirable pain. It would be desirable to use the optimum shape of the pressure probe that gives maximum stress to the muscle with a minimum skin stress. Since the effective stress at the muscle is not observable, it is necessary to establish a quantitative model to predict it. Toward this goal, we developed 3-D finite-element model of human forearm. Four layers (the skin, subcutaneous tissue, muscle and bone) were defined and assumed to be linear elastic materials. Two kinds of cylindrical pressure probes, with diameters of 2 and 10 mm, were constructed. Forty g load was applied for the former and 1000 g load for the latter, so that both probes would give pressure of 124.6 mN/mm2 to the contact area. A pressure with 2 mm-probe resulted in the maximum principal stresses of 1250 and 2.93 mN/mm2 at the epidermis and the muscle, respectively, while that with 10 mm-probe gave 1470 and 47.0 mN/mm2 for those tissues. The maximum principal stress of the epidermis was 427 times larger than that of the muscle in the 2 mm-probe, while the factor was 31.3 times in the 10 mm-probe. These results indicate that the larger probe is more appropriate for measuring muscle pain by transcutaneous pressure. [Jpn J Physiol 54 Suppl:S175 (2004)]
