抄録
Many reports have shown that there are sex differences in pain sensitivity, and that hormonal condition also modulates pain sensitivity. Because muscle pain sensitivity was not studied yet in Japanese, we examined sex differences and differences in different phases of menstrual cycle in muscle pain sensitivity of young Japanese. Healthy subjects (10 males, 10 females in follicular phase, and 10 females in luteal phase) were recruited from students of Aichi Gakusen University and provided informed consent. The age ranged between 18 and 22 years old. Experimental muscle pain was induced in the biceps brachii muscle by eccentric exercise (ECC). A weight was placed around the wrist of undominant arm, and the subjects were asked to flex and extend the arm. Pressure pain threshold of the biceps brachii muscle (PPT), elbow joint angles that the subjects could flex or extend without pain, blood pressure, hemoglobin and skin fold thickness were measured. The females showed a significantly lower basal PPT, maximal blood pressure, and blood hemoglobin content, and their skin fold was thicker than the males. The PPT and blood hemoglobin in luteal phase were significantly lower than the follicular phase. PPT decreased 1 day after ECC and returned to the pre-exercise value 4 days after ECC. This time course in the development of delayed onset of muscle soreness was not different among groups. Present data showed clear sex and menstrual cycle differences in muscle pain threshold. [J Physiol Sci. 2006;56 Suppl:S146]
