Influence Of Sports Brassiere On Female Thermal Physiology During Exercise

With the improvement of health awareness,exercise has become a trend.Exercise is a process of generating heat and sweating,proper sportswear can effectively help athletes diffusion of heat and moisture and improve exercise efficiency.The thermal comfort of sportswear is widely concerned.At present,the subjects of research on the thermal comfort of sportswear are mainly males.There is a significant difference between male and female in the thermal physiology and dressing.The results of the study on the thermal comfort of sportswear using male subjects can not be adapted to the female subjects.Sports brassiere is an additional garment layer for female,wearing sports bras can reduce the breast movement during exercise.To provide firm support to breasts,sports bras are very tight-fit and usually consist of multi-layer(shell fabric and cup pads)that prevents heat and moisture transfer.Therefore,a sports bra can represent a physical advantage but a thermal disadvantage.There are few papers addressing the thermal comfort of sports bra,which is mainly on the temperature changes under bra area and the bra without cup and with sponge pad,almost no research on the bra material is involved.In the paper,the effect of sports bras made of different materials and a common bra on thermal physiology during exercise in hot environment(30oC,44%RH,0.4m/s airflow)was investigated.The two sports bras were of a same design.For bra SW,an ordinary knitted polyester material was used for the shell and a vertical layered nonwoven material was used for the cup pad.For bra CW,a wicking and quick-dry knitted polyester material was used for the shell and a 3D sandwich knitted fabric,which is easy for liquid water to transfer,was used as cup pad material.The experiment in the study included the test of air permeability and water vapor transmission of sports bra materials and the wearing experiment.Seven female undergraduates of breast size 75 B volunteered to participate the wear trials,three bras were tested together with a short sleeve T-shirt and a pair of short pants respectively.The exercise protocol consisted of 30 min sitting rest,three cycles of alternation between 5min walking(5km/h)and 10 min jogging(7km/h),followed by a 5min walking(5km/h)and 30 min sitting rest to recover.The rectal temperature(Tre),skin temperature,and heart rate(HR)were measured during exercise,and the thermal sensation,wetting sensation,comfort sensation and the rating of perceived exertion(RPE)were recorded every 5 minutes.The weights of the nude,sportswear and bras were measured before and after the exercise.Through the analysis of the data,the results are as follows:(1)In the physical test of material,the air permeability of the shell material was better which was with smaller gram weight and density,and the air permeability of the cup pad material was better which was with smaller density.The water vapor transmission of the fabric is related to the fiber composition.The water vapor transmission of fast dry polyester material made of hydrophilic fiber was better than that of the ordinary polyester.The porosity of the cup pad material also affects the water vapor transmission of the cup pad,and the water vapor transmission of the 3D sandwich knitted fabric with larger porosityis was better than that of the ordinary vertical cotton.(2)The order of sweat evaporation was CW>SW>PU,the amount of sweat evaporation was greater,and the heat dissipation of the body was also greater.The heat dissipation of the CW is the largest,and the thermal dissipation of the bra is the best.(3)The temperature rise values of three bras were PU(1.10℃)>SW(0.97℃)>CW(0.81℃)respectively.The temperature rise values of ordinary bra PU was the highest,indicating the highest heat storage.The common bra is poor in the support of the chest,which meant vibration of the soft tissue of the chest produced extra load,increasing extra heat production,so the heat production of bra PU is higher than the other two sports bras.The temperature rise value of CW was the smallest,with the smallest heat storage and the greatest heat dissipation.It shows that the sports bra CW can help the heat dissipation,especially the evaporation heat dissipation.(4)The rectal temperature,skin temperature,and heart rate of bra CW were lower than that of bra SW,which meant the heat dissipation and the thermal comfort of bra CW were better than that of bra SW.Bra CW could help the heat and moisture transfer,probably due to the better air permeability and water vapor transmission of the cup pad material of bra CW.It confirmed that the cup pad material is very important for the thermal comfort of sports bra.The sports bra made of material with good air permeability and water vapor transmission can dissipate the heat and disperse the moisture and make the human body in a more comfortable state with better thermal comfort.