however , insufficient body water 
 due to continuous dehydration caused by prolonged exercise leads to a decrease in plasma 
 volume and cardiac output and an increase in plasma osmolarity and core temperature1 , 2 . 

furthermore , inefficient heat dispersion caused by a decreased rate of blood flow to the 
 skin can accelerate fatigue and deteriorate exercise performance by retaining body heat3 , 4 . 

therefore , to improve exercise performance in athletes and to enhance the effects of regular 
 exercise for health maintenance and promotion , it is important to develop a method that can 
 alleviate exercise - induced rise in body temperature .
far infrared electromagnetic wavelengths of 5.61,000 m can activate cells and promote 
 metabolism when absorbed by the human body .
previous 
 studies verified the efficacy of ge - coated clothing5 , 
 6 , and observed that ge - containing 
 fibers emitted far infrared rays and anions and had an antibacterial effect .
these results 
 suggested that ge - containing fibers could promote blood circulation and had the potential to 
 suppress fatigue and relieve thermal stress by wearing ge - containing and/or ge - coated 
 clothing during exercise .
however , a scientific approach to proving such an effect has been 
 very limited . therefore , the present study aimed to investigate the effects of wearing ge - coated 
 functional clothing during exercise on tympanic temperature ; thermal sensation ; heat shock 
 protein 70 ( hsp70 ) , which is involved in homeostatic regulation in exercise - induced thermal 
 stress ; and lactate , an indicator of fatigue .
nine healthy and untrained male subjects ( age : 20.2  0.4  years ; height : 175.7  2.8  cm ; 
 weight : 73.1  10.1  kg ; body mass index : 23.7  3.0  kg / m ; muscle mass : 34.6  
 2.9  kg ; fat mass : 12.4  6.2  kg ; percentage body fat : 16.3  6.3% ; resting heart rate : 70.9 
  3.6 beats / min ; systolic blood pressure : 118.6  7.3 mmhg ; diastolic blood pressure : 72.6  
 8.4 mmhg ) volunteered as subjects for the present study . the study was conducted in 
 accordance with the standards set by the latest revision of the declaration of helsinki , and 
 all the subjects provided written informed consent in accordance with the department of 
 sport for all studies at soongsil university guidelines .
anthropometric measurements included height , body composition , resting heart rate , and 
 blood pressure .
height and body composition were measured using a stadiometer ( seca213 ; 
 seca , germany ) and a bioimpedance analysis device ( inbody720 ; biospace , korea ) , 
 respectively .
resting heart rate and blood pressure were measured in a seated position , 
 using a heart rate monitor ( polar a5 ; polar , finland ) and a mercury sphygmomanometer 
 ( trimline ; pymah , usa ) , respectively .
the 9 subjects participated in control and experimental tests , both involving 60  min of 
 running on a treadmill at an exercise intensity of 75% heart rate reserve in a laboratory 
 with temperature and humidity of 18.5  0.5  c and 36.0  1.0% , respectively .
the clothing 
 worn by each subject consisted of a half - sleeve t - shirt and short pants . during the control 
 test
, the participants wore conventional clothing ( which had not received functionality 
 treatment ) ; during the experimental test , they wore ge - coated functional clothing ( which had 
 been prepared by coating the same clothing used for the control test with ge ) . according to 
 the result of a comparison test using fourier
transform infrared spectroscopy ( ft - ir ) and a 
 black body at 37  c , which is almost the same as body temperature , the far infrared rays 
 emitted by the ge - coated functional clothing characteristically showed an emission rate of 
 0.893 m and a wavelength of 3.44  10  w / mm .
tympanic temperature was measured using infrared ear thermometry ( thermoscan irt-4520 ; 
 braun , germany ) as a surrogate for core temperature .
thermal sensation was measured using a 
 disc score7 . using a 22-gauge needle , a serum separator tube ( becton dickinson , usa ) , and an 
 ethylenediaminetetraacetic acid - coated tube ( becton dickinson , usa ) ,
8  ml of blood was 
 collected from the antecubital vein of each subject immediately before exercise ( ibe ) and 
 immediately after exercise ( iae ) .
the collected blood samples were centrifuged for 15  min at 
 3,000  rpm , and then stored at 80  c until analysis .
the serum hsp70 levels were determined 
 using a high - sensitivity , commercially available enzyme - linked immunosorbent assay ( elisa ) 
 kit ( assay designs , usa ) .
the absorbance was measured at 450  nm with a microplate reader 
 ( emax ; molecular devices , usa ) .
the plasma lactate levels were determined using a clinical 
 chemistry analyzer ( ektachem dt 60 ; eastman kodak , usa ) .
statistical analyses were performed using spss software , version 21.0 for windows ( spss 
 inc .
data are presented as mean  standard deviation ( sd ) . for identifying 
 differences in normally distributed results , a two - way repeated analysis of variance ( anova ) 

when significant time by trial interactions occurred , simple main effects 
 were assessed using the independent and paired t - tests .
the tympanic temperature , disc score , hsp70 , and lactate levels are presented in table 1table 1.germanium-coated functional clothing effects on tympanic temperature , disc score , 
 hsp70 , and lactate levelsvariablecontrol ( n=9)experimental ( n=9)ibeiaeibeiaetym t
36.73  0.3037.16  0.66disc score1.33  0.872.44  1.13*1.22  0.971.11  1.17hsp70 ( ng / ml)0.184  0.0170.205  0.027 * 0.193  0.0170.210  0.019*lactate ( mmol / l)1.48  0.602.84  1.34 * 1.12  0.452.03  0.89*data are presented as mean  sd .
tym t : tympanic temperature ; ibe : immediately before 
 exercise ; iae : immediately after exercise ; rating scale range , 3 to 4 ; 
 * p<0.05 vs. ibe ; p<0.05 vs. control test .
the tympanic temperature iae was significantly elevated compared to the 
 temperature ibe in the control test ( p<0.05 ) , while no significant change was observed in 
 the experimental test . in both tests ,
the hsp70 and lactate levels measured iae were 
 significantly increased compared to the levels ibe ( p<0.05 ) .
the disc score iae was 
 significantly increased compared to the score evaluated ibe in both tests ( p<0.05 ) , and 
 it was significantly higher iae in the control test compared to that in the experimental 
 test ( p<0.05 ) .
tym t : tympanic temperature ; ibe : immediately before 
 exercise ; iae : immediately after exercise ; rating scale range , 3 to 4 ; 
 * p<0.05 vs. ibe ; p<0.05 vs. control test
organic ge has been reported to promote immune activation and play an important role in 
 regulating antioxidative activities8 , 9 .
for this reason , it has been widely 
 utilized for manufacturing not only health functional foods but also bracelets , necklaces , 
 and textile products such as underwear . to verify the effects of wearing ge - coated 
 functional clothing during exercise on thermal stress , in the present study ,
the results in the 
 control test ( wearing common clothing ) showed a significant increase in tympanic temperature 
 measured iae ; however , the experimental test ( wearing ge - coated clothing ) did not show such 
 an increase .
in addition , the measurement of thermal sensation using the disc score showed 
 significantly lower levels iae in the experimental test than that in the control test .
the 
 reasons for such results could be that ge - coated clothing alleviated exercise - induced 
 thermal stress by promoting blood circulation during exercise .
this interpretation is 
 supported by the observations that increase in skin blood flow during exercise is an 
 effective mechanism for dispersing heat accumulated in the body10 , and that ge - containing clothing had the effect of 
 promoting blood circulation5 , 6 . in both tests in the present study ,
the serum hsp70 and 
 plasma lactate levels showed a significant increase iae , but without a significant 
 difference between the 2 tests .
the result for hsp70 levels supports the results of previous 
 studies that reported a significant increase after acute exercise11 , 12 , and suggests 
 that not only high core temperature but also various other factors contribute to hsp70 
 expression .
this interpretation is consistent with the reports of a positive correlation 
 between hsp70 expression and core temperature13 ; however , hsp70 expression was also affected by various 
 physiological and environmental stress factors such as heat , training status , oxidative 
 stress , ph change in the body , and glucose depletion14 , 15 .
conversely , the lactate 
 level is considered independent of thermal stress , probably due to the same level of 
 exercise intensity used for both tests ; this result suggests that wearing ge - coated clothing 
 during exercise exerts no significant effect on exercise - induced fatigue .
this 
 interpretation is supported by ishii and nishida , who reported that circulating lactate 
 concentrations were dependent on exercise intensity16 , and also by mohr et al . , who reported that exercise under 
 different environmental conditions ( 21  c vs. 43  c ) showed no difference in plasma lactate 
 concentration in spite of significant differences in core temperature17 .
in conclusion , the present study suggests that wearing ge - coated clothing during endurance 
 exercise may have the positive effect of alleviating thermal stress that accumulates during 
 exercise .
 [ purpose ] the present study investigated the effects of wearing germanium - coated 
 functional clothing on tympanic temperature , thermal sensation , heat shock protein 70 
 ( hsp70 ) , and lactate during endurance exercise . [ subjects and methods ] nine healthy and 
 untrained male subjects were enrolled . 
 subjects ran for 60  min on a treadmill ( 75% heart 
 rate reserve ) in the following 2 tests : 1 ) control test ( wearing conventional clothing ) 
 and 2 ) experimental test ( wearing germanium - coated functional clothing ) . during each test 
 , 
 the tympanic temperature and thermal sensation were measured , and blood samples were 
 collected immediately before exercise and immediately after exercise . 
 thermal sensation 
 was measured using a disc score . 
 [ results ] the tympanic temperature immediately after 
 exercise was significantly increased compared to the temperature immediately before 
 exercise in the control test , while no significant change was observed in the experimental 
 test . in both tests , 
 the disc score and hsp70 and lactate levels immediately after 
 exercise were significantly increased compared to those immediately before exercise . in 
 addition , the disc score immediately after exercise was significantly higher in the 
 control test than in the experimental test . 
 [ conclusion ] wearing germanium - coated 
 functional clothing during endurance exercise may have the positive effect of alleviating 
 thermal stress that accumulates in the body during exercise . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION