Effects Of Low-Temperature Environmental Exercise On Condensate Airway Function And Biomarkers Of Exhaled Breath

Objective:To conduct high intensity or long time exercise in low-temperature environment,inhale a large amount of relatively cold and dry air,cause the airway to cool down and dry,trigger the pathological and physiological changes of the airway,and make the airway become another organ with a large level of oxidative stress caused by exercise besides muscle tissue.As a new non-invasive method for detecting airway status,exhaled breath concentration（EBC）can be repeatedly collected in a short time without affecting the medium concentration of the airway.By analyzing the changes of airway function,oxidative stress,inflammatory reaction and other kinds of markers in EBC during exercise in low-temperature environment,the change characteristics of markers in EBC during exercise in low-temperature environment are discussed,so as to provide more accurate functional status of the airway,and lay a preliminary foundation for the construction of non-invasive and convenient monitoring means and guarantee of airway health for people who exercise in low-temperature environment.Methods:Ten young subjects（6 males and 4 females,age:23.9±0.8 years old,23.2±1.5 years old）who actively participated in winter sports were recruited and randomly cross-controlled experimental design was adopted.The subjects were tested on the treadmill at low（about 40%HRR）,medium（about 60%HRR）,and high（about 80%HRR）intensity under normal-temperature（21.2±2.3℃）and low-temperature（-5.2±1.9℃）.A single intensity exercise test was randomly conducted every day,and all the exercise tests were conducted at the same time interval（24h interval）.Test the FVC of subjects after resting and three different intensities of exercise,and collect the EBC after exercise for index analysis.The oxidative stress markers（H₂O₂ and NO₂^-）in EBC were detected by biochemical assay.The oxidative stress markers（MDA and 8-epi-PGF2α）,inflammatory markers（TXB2,PGE2,LTB4 and LXA4）and other markers（LA and CRP）in EBC were detected by enzyme-linked immunosorbent assay.Results:（1）Effects of different environments and different intensities of exercise on ventilation function:In normal-temperature environment,FEV1.0 was significantly decreased after 60%HRR and 80%HRR exercise compared with that before exercise（P<0.01,P<0.01）.Between different exercise intensities,FEV1.0 was significantly lower after 60%HRR and 80%HRR exercise than after 40%HRR exercise（P<0.01,P<0.01）.In low-temperature environment,compared with before exercise,FEV1.0 decreased significantly after three different intensity exercise（P<0.01,P<0.01,P<0.01）,decreased by 16.2%,13.5%and 17.4%respectively.The combination of exercise environment and exercise intensity resulted in a decrease of FEV1.0 level by more than 10%,but there was no significant difference between different exercise intensities.The FEV1.0 level before exercise in low-temperature environment and FEV1.0 level after 40%HRR exercise were significantly lower than those in normal-temperature environment（P<0.01,P<0.01）.（2）Effects of different environments and different intensities of exercise on biomarkers in EBC:（1）At normal-temperature:compared with before exercise,PGE2 in EBC decreased significantly after 40%HRR exercise（P<0.05）,and H₂O₂,TXB2,LXA4 and LA increased significantly（all P<0.01）.After 60%HRR exercise,H₂O₂,NO₂^-,MDA,8-epi-PGF2α,TXB2,LTB4,LXA4,LA and CRP were significantly increased（LTB4:P<0.05,the rest P<0.01）;NO₂^-,MDA,8-epi-PGF2α,TXB2,LTB4,LXA4,LA and CRP were significantly increased after 80%HRR exercise（all P<0.01）.Among different exercise intensities,compared with40%HRR exercise,NO₂^-,MDA,PGE2 and CRP were significantly increased after 60%HRR exercise（all P<0.01）.NO₂^-,MDA,8-epi-PGF2α,TXB2,PGE2 and CRP were significantly increased after 80%HRR exercise（PGE2:P<0.05,the rest P<0.01）.Compared with60%HRR exercise,the concentration of LA after 80%HRR exercise was significantly lower（P<0.05）,and the concentrations of 8-epi-PGF2α,TXB2 and CRP were significantly increased（PGE2:P<0.05,the rest P<0.01）.（2）In low-temperature environment:compared with before exercise,MDA concentra-tion decreased significantly after 40%HRR exercise（P<0.01）,and NO₂^-,PGE2 and LA increased significantly（all P<0.01）.After 60%HRR exercise,the concentration of8-epi-PGF2αdecreased significantly（P<0.05）,and H₂O₂,NO₂^-,MDA,LTB4 and LA increased significantly(LTB4:P<0.05,the rest P<0.01;after 80%HRR exercise,8-epi-PGF2α,TXB2,LTB4 and LXA4 were significantly decreased（TXB2:P<0.05,the rest P<0.01）,H₂O₂and LA were significantly increased（P<0.01,P<0.01）.Between different exercise intensities,compared with 40%HRR exercise,PGE2,LTB4 and LA concentrations after 60%HRR exercise were significantly lower（LA:P<0.05,the rest P<0.01）,H₂O₂and MDA were significantly increased（P<0.01,P<0.01）;after 80%HRR exercise,NO₂^-,8-epi-PGF2α,TXB2,PGE2,LXA4 and LA were significantly decreased（LXA4 and LA:P<0.05,the rest P<0.01）,MDA was significantly increased（all P<0.01）.Compared with60%HRR exercise,NO₂^-,8-epi-PGF2α,TXB2,LTB4 and LXA4 concentrations were significantly decreased after 80%HRR exercise（all P<0.01）,and H₂O₂was significantly increased（all P<0.01）.（3）Exercise in different environments:compared with low-temperature environment,H₂O₂,MDA,8-epi-PGF2α,TXB2 and LTB4 before exercise were significantly higher than those in normal-temperature environment（all P<0.01）.After 40%HRR exercise,NO₂^-,MDA,8-epi-PGF2α,PGE2 and LTB4 were significantly higher than those in normal-temperature environment（NO₂^-and PGE2:P<0.05,the rest P<0.01）;after 60%HRR exercise,LA and CRP were significantly lower than those in normal-temperature environment（P<0.01,P<0.01）,and H₂O₂,MDA and LTB4 were significantly higher than those in normal-temperature environment（all P<0.01）.After 80%HRR exercise,NO₂^-,8-epi-PGF2α,TXB2,LTB4,LXA4,LA and CRP were significantly lower than those in normal-temperature environment（NO₂^-:P<0.05,the rest P<0.01）,H₂O₂and MDA were significantly higher than those in normal-temperature environment（P<0.01,P<0.05）.Conclusion:（1）There were obvious exercise bronchial stenosis after moderate and high intensity exercise at room temperature,and obvious exercise bronchial stenosis after different intensity exercise at low temperature.The increase of exercise intensity at room temperature aggravates bronchial stenosis.Compared with normal temperature environment,the increase of exercise intensity at low temperature tends to alleviate bronchial stenosis.（2）Low-intensity exercise at room temperature slows down the level of airway oxidative stress and the degree of inflammatory response,and with the increase of exercise intensity,the level of airway oxidation and the degree of inflammatory response show an upward trend.Compared with the normal temperature environment,low and medium intensity exercise at low temperature will lead to the increase of airway oxidative stress and the aggravation of airway inflammatory injury.The level of oxidative stress is the highest after medium intensity exercise,but the degree of oxidative stress and inflammatory response is reduced after high intensity exercise.（3）Compared with high intensity exercise in low temperature environment,there is no greater adverse effect on airway function.This phenomenon may be related to the low level of oxidative stress and inflammatory response.