firefighting protective clothing is designed to be put on quickly and easily by fire 
 fighters before an emergency . some examples of the design features of firefighting 
 protective clothing include being fire proof and waterproof , which help protect the fire 
 fighters wearing the protective clothing1 . however , when firefighters wear easily firefighting protective clothing , physical energy can 
 be consumed because of the heavy weight of the firefighting protective clothing . also , this 
 physical exhaustion can lead to overwork and fatigue , as well as acting as the primary 
 factor of musculoskeletal injuries2 . fire fighters who work in a high temperature environments discharge a large amount of sweat 
 as work strength is increased . in addition , body fluids can lead to dehydration , which can 
 negatively affect the circulation and temperature regulation of the body by intensifying the 
 concentration of the blood3 . in addition , 
 the body temperature rising , heat exhaustion , dehydration , heat cramps , heat exhaustion , and 
 accompanying disorders of the central nervous system can occur due to prolonged expose to 
 high temperatures4 . reactive oxygen species ( ros ) , which are constantly formed in the human body , are suggested 
 to contribute to pathological processes during aging and in many diseases such as diabetes , 
 atherosclerosis , and cancer5 . oxidative 
 stress results when the amount of ros exceeds the level of the antioxidant defense system , 
 including the endogenous scavenger enzymes ( superoxide dismutase , glutathione peroxidase , 
 and catalase ) , and exogenous dietary antioxidants6 . recent studies have reported the effect of wearing personal protective equipment ( ppe ) on 
 physiological strain such as blood pressure ( bp ) and heart rate responses or maximal oxygen 
 uptake ( vo2max ) in firefighters7,8,9 . firefighters wearing full ppe and self - contained breathing apparatus ( scba ) have exaggerated 
 systolic bp and heart rate levels during each stage of incremental exercise , as well as 
 during recovery time8 . also ppe with scba 
 during graded exercise treadmill have a negative impact on vo2max9 . it is well known that the metabolic challenge during physical exercise with maximal oxygen 
 uptake results in an elevated generation of reactive oxygen species ( ros ) that are important 
 modulators of muscle contraction , antioxidant protection , and oxidative damage repair , which 
 at moderate levels generate physiological responses10 . however , it is not completely known whether wearing ppe during 
 training can induce oxidative stress . thus , in this study , we investigated the 
 oxidant / antioxidant responses of current fire fighters wearing firefighting protective 
 clothing while performing physical activities in an environment similar to firefighting 
 situations . the 12 subjects were firefighters recruited from a local fire station . the subjects were 
 screened according to the following criteria : those who were 20  years of age and those who 
 were in good health . subjects were excluded if their cardiovascular systems were unstable , 
 had diabetes , hypertension , or musculoskeletal or neurological diseases . information 
 regarding individual characteristics , health status , lifestyle factors including smoking , 
 alcohol , and exercise habits were collected by questionnaire . the purpose and procedure of 
 the study were explained to the subjects , and informed consent for voluntary participation 
 was received from each . this study was performed after being approved by the ethics 
 committee of kyungnam university . all enrolled firefighters underwent two treadmill 
 training within a 2-week period , at the same time of day : one in regular clothes ( rc ) , and 
 one in full firefighter ppe . the weight of ppe including firefighting protective garment 
 ( 6.6  kg ) , helmet ( 1.2  kg ) , firefighting protective shoes ( 2.9  kg ) , firefighting gloves 
 ( 100  g ) , and a respiratory device ( 11.3  kg ) was 22.1  kg . all trainings were performed that 
 have 9 mets with 25 degree c for 20  min . dietary intake data were collected by trained interviewers using 24-hour recall method for 
 one day before staring each test . the can pro 3.0 ( korean nutrition society , seoul , korea ) 
 was used to analyze nutrient intake of the study subjects . polar heart rate ( sport tester pe 3000 , polar , finland ) was used to monitor participants 
 exercise heart rate . perceived exertion was measured using rating of perceived exertion 
 ( rpe)11 . the scale is attached to a 
 10-point rating scale with 0 : very very light and 10 : very very hard . blood samples were obtained before , right after , and 40  min after training by venipuncture 
 into a heparinized sterile tube , and were processed within 2  h. lymphocyte isolation for the 
 comet assay was performed using the histopaque 1077 ( sigma ) , followed by two washes of 
 isolated lymphocytes with pbs . the remaining blood was centrifuged at 1,500  rpm for 30  min 
 to obtain the plasma . the separated plasma was then stored at 80 c until further analysis 
 of total plasma free radical levels . erythrocytes were washed four times with pbs ( ph 7.4 ) 
 and were suspended in buffer for erythrocyte antioxidant enzyme analyses . plasma total radical - trapping antioxidant potential ( trap ) was measured after rice - evans 
 and miller s inhibition assay12 , as 
 described previously . plasma baseline ldl conjugated diene ( cd ) levels were determined 
 according to the methods outlined by ahotupa et al . with slight modifications13 . plasma trap level was calculated relative 
 to the calibration curve of trolox and was expressed as teac ( trolox ) . the erythrocyte 
 pellet was resuspended in ice - cold water and was processed for antioxidant enzyme activities 
 in the separated supernatants , using a uv / vis spectrometer . catalase activity was measured 
 by assessing the shrinkage of hydrogen peroxide , which was added to the erythrocyte 
 suspension for 30 s14 . glutathione 
 peroxidase activitiy ( gsh - px ) was determined according to the method described by 
 beutler15 . superoxide dismutase ( sod ) 
 activity was assayed in erythrocyte - suspension by the procedure of marklund and 
 marklund16 . the unit of the enzyme was defined as the amount 
 which inhibits the autoxidation of pyrogallol by 50% . the 
 isolated leukocytes were subjected to oxidative stress by suspension in pbs with 100 m 
 h2o2 . the leukocytes in agarose were added to the slides and then 
 immersed in lysis solution ( 2.5  m nacl , 100  mm edta , 10  mm tris , and 1% sodium 
 laurylasarcosine ; 1% triton x100 and 10% dmso ) for 1 hr at 4  c . for electrophoresis of the 
 dna , an electric current of 25 v/300  3 ma was applied for 20  min at 4  c . measurements 
 were made by image analysis ( komet 4.0 ; kinetic imaging , liverpool , uk ) and fluorescence 
 microscope ( dmlb ; leica wetzlar , germany ) . the spss statistical package , version 18.0 ( ibm inc . , chicago , il , usa ) , was used for 
 statistical analysis . statistical differences before and after trainings within groups were considered significant 
 at p<0.05 by paired t - test . the average 
 height , weight , and bmi of the subjects were 175.4  4.3  cm , 71.8  5.9  kg , and 23.3  
 1.5  kg / m and the length of service for firefight was 7.1  6.4  years . ten of 
 the subjects exercised regularly and their frequency of exercise was 4.3  0.3 times per 
 week . table 1table 1.energy and antioxidant nutrients intake status in rc and ppe testvariablesrc testppe testenergy ( kcal / day)2,215.7  200.42,084.7  174.4vitamin c ( mg / day)85.7 14.7103.1  15.9retinol ( g / day)224.0  93.7296.9  68.3-carotene ( g / day)3,202.1  761.22,965.4  493.4values are means  se . rc : regular clothing ; ppe : personal protective equipment ; ns : 
 not significant . the values of nutrients intake were estimated by a one - day 24-hr 
 recall method . presents the intake status of energy and antioxidant nutrient , such as vitamin 
 c , retinal , and -carotene one day before each study period and the energy intake and 
 antioxidant nutrients intake were not significantly different between the two periods . rc : regular clothing ; ppe : personal protective equipment ; ns : 
 not significant . the values of nutrients intake were estimated by a one - day 24-hr 
 recall method . the physiological responses to the treadmill walking training are shown in table 2table 2.effect of firefighting personal protective equipment on the heart rate and rating 
 of perceived exertion during treadmill walking trainingvariablesgroupbefore exerciseright after exercisechanges of before and after exerciseheart rate ( beats / min)rc test75.8  3.2133.3  3.657.4  4.1ppe test86.4  3.2176.6 2.790.2  4.6rating of perceived exertionrc test2.5  0.56.0  0.53.5  0.6ppe test3.6  0.39.1  0.35.5  0.4values mean statistical differences for p<0.001 ( paired t - test ) between 
 before exercise and right after exercise . mean statistical 
 differences for p<0.05 , p<0.001 ( student t - test ) between rc and ppe .. the treadmill walking training induced significant increases in heart rate 
 and rating of perceived exertion either in regular clothing ( rc ) or in ppe . the changes of 
 heart rate and rpe were significantly higher during the ppe test compared with the rc 
 test . mean statistical differences for p<0.001 ( paired t - test ) between 
 before exercise and right after exercise . mean statistical 
 differences for p<0.05 , p<0.001 ( student t - test ) between rc and ppe . the effect of firefighting ppe on the oxidative / antioxidative parameters during training is 
 shown in table 3table 3.effect of firefighting personal protective equipment on the 
 oxidative / antioxidative parameters during treadmill walking trainingvariablesgroupbefore exerciseright after exercise40 min after exerciseplasmacd ( m)rc test5.2  0.95.4  0.75.3  0.6ppe test5.5  0.86.2  115.5  0.7trap ( mm)rc test1.11  0.081.11  0.111.05  0.08ppe test1.16  0.121.24  0.101.16  0.13erythrocytessod ( u/ g hb)rc test1,632.9  64.21,484.8  92.71,646.5  44.3ppe test1,688.9  58.21,614.5  49.71,647.1  50.8cat ( kg/ g hb)rc test110.6  5.4112.8  6.7112.6  6.5ppe test109.8  6.5106.7  4.1113.5  4.5gpx ( u/ g hb)rc test26.1  3.827.0  4.127.9  4.0ppe test26.7  3.029.2  5.123.8  3.0leukocytesdna damage ( % tail intensity)rc test83.1  1.684.8  1.384.0  1.4ppe test69.4 rc : regular clothing ; ppe : personal protective equipment ; cd : 
 conjugated dienes ; trap : total radical trapping antioxidant potential ; sod : superoxide 
 dismutase ; cat : catalase ; gpx : glutathione peroxidase . mean 
 statistical differences for p<0.05 , p<0.01 , p<0.001 ( paired t - test ) between 
 before exercise and right after exercise . * mean statistical differences for p<0.05 ( paired t - test ) between and right after 
 exercise and 40  min after exercise . mean statistical differences for 
 p<0.01 ( paired t - test ) between before exercise and 40  min after exercise .. plasma cd ( an indicator for lipid peroxidation ) and trap increased 
 significantly during the treadmill walking training and then recovered to the baseline 
 levels after the 40  min of rest in the subjects with ppe . also , wearing ppe during training 
 resulted in the increased of leukocyte dna damage , which was recovered after in 40  min of 
 rest , but not reached to the baseline level . no changes were found in of all the tested parameters 
 in the rc group during the treadmill walking training . rc : regular clothing ; ppe : personal protective equipment ; cd : 
 conjugated dienes ; trap : total radical trapping antioxidant potential ; sod : superoxide 
 dismutase ; cat : catalase ; gpx : glutathione peroxidase . mean 
 statistical differences for p<0.05 , p<0.01 , p<0.001 ( paired t - test ) between 
 before exercise and right after exercise . * mean statistical differences for p<0.05 ( paired t - test ) between and right after 
 exercise and 40  min after exercise . mean statistical differences for 
 p<0.01 ( paired t - test ) between before exercise and 40  min after exercise . in the present study , we investigated whether firefighting ppe induces oxidative stress 
 during performing physical activities in an environment similar to firefighting situations . we found increased plasma lipid peroxidation measured by conjugated dienes level , leukocyte 
 dna damage measured by comet assay , and plasma total antioxidant capacity measured by trap 
 assay right after the treadmill walking training with wearing ppe in healthy firefighters , 
 while they remained unchanged during the treadmill training with wearing regular 
 clothes . diene conjugation in circulating ldl used in our study is an indicator of oxidized ldl 
 in vivo . the spectrophotometrical determination of baseline diene 
 conjugation in ldl , which arises as an early event of lipid peroxidation reaction , is one of 
 the important methods for monitoring ldl oxidation18 . dna damage is known to be one of the most sensitive biological 
 markers for evaluating oxidative stress representing the imbalance between free radical 
 generation and deficiencies in the antioxidant system19 , 20 . assessment of the total 
 radical trapping antioxidant potential ( trap ) , which is the combined capacity of all 
 antioxidants to neutralize circulating free radicals may be a marker to signal the beginning 
 of an oxidant antioxidant imbalance in the body fluids21 . it has been reported an augmentation of conjugated dienes , dna 
 strand breaks , oxidative dna damage , and total antioxidant status in human blood after a 
 single bout of intense training22,23,24,25 . in our study , the treadmill walking 
 training in itself for 20  min ( 9 mets , 6  km / h ) was not enough to induce oxidative stress . 
 however , walking training with physical burden of firefighting ppe including protective 
 garment , helmet , firefighting protective shoes , firefighting gloves , and a respiratory 
 device ( 22.1  kg ) could induce oxidative stress by increasing the generation of ros . to the 
 best of our knowledge , this is the first study to report oxidative stress in firefighters 
 during activity with wearing ppe . it is postulated that the higher oxygen consumption 
 through the self - contained breathing apparatus ( scba ) in ppe group as evidenced by the 
 higher heart rate and rating of perceived exertion ( table 2 ) also contributed to elevate levels of free radicals as shown in increased 
 levels of plasma conjugated dienes and leukocyte dna damage . to minimize oxidative stress 
 and remove free radicals the body uses a very effective antioxidative defense system 
 containing exogenous antioxidants like urate , tocopherol and ascorbate and endogenous 
 antioxidant enzymes like sod , cat or gpx26 . increased plasma level of trap might be an evidence of exertion to 
 minimize oxidative stress induced by physical burden of ppe , whereas no contribution of the 
 endogenous antioxidant enzymes to this redox control were found in our study . although the oxidative stress induced by treadmill training with ppe was restored during 
 40  min of recovery condition , repeated exposure to oxidative stress during firefighting 
 might be detrimental to firefighters health . it is reported that firefighters have one of 
 the nation s highest occupational fatality rate in the us27 and the leading cause of death in firefighters is 
 cardiac - related28 , 29 . the limitation of this study was that only twelve male firefighters were included in this 
 study , therefore , the results can not be generalized to the entire firefighter population . further studies can investigate the effect of ppe on oxidative / antioxidative status in other 
 populations . in conclusion , our study provides evidence that wearing ppe during firefighting work could 
 induce oxidative stress , which was enough to produce dna damage in leukocytes . future 
 studies are needed to understand the effect of antioxidant supplementation on oxidative 
 stress possibly induced by firefighting work with the heavy weight of fire protection 
 equipment to prevent the oxidative stress related diseases in firefighters .
[ purpose ] the purpose of this study was to investigate the influence of personal 
 protective equipment on the oxidant / antioxidant parameters and dna damage in firefighters 
 during training and recovery . 
 [ subjects and methods ] twelve male nonsmoking volunteer 
 firefighters ( 35.1  7.2  years ) underwent two maximal treadmill training ( 9 mets , 6  km / h ) , 
 within 2 weeks , one in regular clothes and one in personal protective equipment weighing 
 22.1  kg . 
 blood samples were obtained before , right after , and 40  min after training . 
 plasma conjugated dienes , total radical trapping antioxidant potential , erythrocytes 
 antioxidant enzymes activities , and leukocyte dna damage were measured . 
 [ results ] wearing 
 personal protective equipment during treadmill walking training resulted in increases of 
 plasma conjugated dienes , total radical trapping antioxidant potential , and leukocyte dna 
 resistance to oxidative stress , which were recovered after in 40  min of rest . 
 erythrocyte 
 antioxidant enzymes activities remained unchanged during the training either with regular 
 clothes or personal protective equipment . 
 [ conclusion ] these results suggest that wearing 
 personal protective equipment during firefighting work could induce oxidative stress , 
 which was enough to produce dna damage in leukocytes .