Effects and mechanisms of heat-and-steam generating sheet on relieving menorrhalgia

Abstract

Many women complain of abdominal pains and lumbago during their menstrual period. In this study, we analyzed the effects of a heat-and-steam generating (HSG) sheet on relieving abdominal and lumbar pains in the menstrual period. The HSG sheet warms the body by evaporating warm steam for five to eight hours and are effective in relieving menorrhalgia; however, the mechanism is unclear. To clarify the mechanism, we observed changes of uterine blood flow and changes of autonomic nerve activities. Subjects were 15 women between 19 and 25 yrs old with a regular menstrual cycle. We applied an HSG sheet to each subject for 5 hrs. We recorded an electrocardiogram and calculated the low (LF) and high (HF) frequency components of the power spectrum of R-R intervals. We measured three skin temperatures in the abdominal area warmed by the HSG sheet, 2 cm above the warmed area and lumbar regions for 5 consecutive hrs. We also measured blood velocity of the uterine artery just before and after warming the abdominal region with an HSG sheet. Measurements were performed twice during the subjects' menstrual periods and follicular phase. Hemodynamics of the uterine artery were not significantly changed before and after warming. Our preliminary examinations suggested that the LF/HF ratio may be higher while the subjects were suffering menorrhalgia than while the subjects were relieved from the pain. [J Physiol Sci. 2008;58 Suppl:S103]