Study On The Effect Of Mechanical Interaction Between Tight Garment And Body On The Skin Blood Flow

Nowadays, more and more people wear various tight-fit garments, such as foundationwear, stockings, tight pants, jeans and etc. The mechanical interaction between garmentand body may have positive or negative influence on physiological system, so the safetyand comfort begin to draw more and more attentions from consumers, clothing designers,engineers and researchers.The mechanical loads on the body by tight garments consist of normal load(pressure)and tangential load(shear), and they have different influence on the soft tissue. The softtissue becomes thin along the normal direction, and it becomes shear along the tangentialdirection. In this study, the effect and mechanism of pressure and shear load on skin bloodflow would be investigated. Five female subjects were recruited, and three kind ofloads(pressure, shear, pressure and shear) were exerted on the shank, under which the skinblood flow at two observation points(the front and back of shank) was observed. Thewavelet analysis was carried out on blood mass signals to find out the mechanism. Theconclusions were obtained as follows: under lower pressure or little shear, the bloodvelocity decreased at the observation points, and the blood mass increased, under higherpressure, the mass increment declined, under bigger shear, the mass turned to decrease;compared to the pressure, the shear had obvious negative effect on the skin blood flow, andthe blood mass tend to decrease under shear; the thicker soft tissue became a buffer whenthe loads were exerted, however the loads could not be weakened at the thin part, so themass increment tend to decline under higher pressure and the mass decrease under shear;under shear, the blood velocity decreased, which means the required blood perfusion andconcentration of oxygen could be finished in short time, based on the capillaries open-closemodel, the open time of capillaries would be shortened, so the open-close frequency ofcapillaries would increase and the open rate decrease, resulting in the blood mass decrement, while under certain pressure, the blood velocity decreased, so other changeswere also opposite to those under shear. The wavelet analysis on blood mass signalsrevealed that the characteristic frequency of myogenic activity increased under shear loads,and it decreased under pressure. The characteristic frequency of myogenic activity wasconsistent with the open-close frequency of capillaries, thus the myogenic activityfrequency change proved that the theoretical analysis was right.