walking is one of the recommended modes of exercise for obese individuals because of its 
 merits in terms of safety , accessibility , and popularity , as well as proven efficacy in 
 weight management1 , 2 .
however , walking over a terrain of repetitive uphill and downhill 
 inclines in activities such as mountain climbing can cause excessive fatigue and muscle 
 damage3 .
in particular , repetitive 
 eccentric contractions of the lower limb muscles during downhill walking places sarcomeres 
 under excessive tensile stress .
this stress can destroy sarcomeres by extending them beyond 
 their normal length , sometimes involving a local inflammatory reaction , and can thereby lead 
 to delayed onset muscle soreness or exercise - induced muscle damage .
the indexes reflecting 
 such conditions are serum creatine kinase ( ck ) and lactate dehydrogenase ( ldh ) levels4 , 5 .
it 
 has been reported that the use of a pole during walking over an uneven terrain could improve 
 gait stability and balance , and that its use during downhill terrain walking can reduce the 
 load and stress on the lower limbs ( such as the ankle , knee , and hip joints)6,7,8 .
however , previous studies on the effects of 
 a pole during downhill walking have been limited to the kinetic aspects such as the 
 reduction of knee joint forces or the load on the lower extremity joints .
meanwhile , it has been suggested that increases in peripheral cartilage oligomeric matrix 
 protein ( comp ) levels after exercise could serve as a biomarker of cartilage degradation and 
 damage9 , and pruksakorn et al .
in addition , according to a comparative study by 
 andriacchi et al . that measured the maximum flexion of the lower extremity joints during 
 various routine activities , the flexion of the knee joint was approximately 4 times greater 
 during walking down stairs than during walking over level ground11 . taken together , such previous reports suggest that the 
 use of a pole during downhill walking may alleviate the burden on lower extremity joint 
 cartilages ; however , thus far , there has been no report examining this potential 
 benefit .
accordingly , this study aimed to investigate the effect of the use of a trekking pole on 
 muscle and cartilage damage and fatigue during downhill walking .
the study specifically 
 examined obese women who had less muscle mass than men and whose heavy weights were likely 
 to increase the burden on their lower limb muscles and joints during walking .
eight obese women ( average age of 21.1  1.8  years , average height of 164.8  4.9  cm , 
 average weight of 61.8  7.7  kg , average body fat percentage of 33.9  1.4% , and average 
 resting heart rate of 69.6  3.7 beats / min ) with body fat percentages ranging from 30.0 to 
 36.1 volunteered as subjects for this study .
the study conformed to the standards set by the 
 latest revision of the declaration of helsinki , and all subjects read and signed a written 
 informed consent statement consistent with the guidelines of the department of physical 
 education at yonsei university .
height and body composition were measured using a stadiometer ( seca213 ; seca , hamburg , 
 germany ) and a bioimpedance analysis ( bia ) device ( inbody720 ; biospace , seoul , korea ) , 
 respectively .
resting heart rate was measured in a seated position using a heart rate 
 monitor ( polar a5 ; polar , kempele , finland ) .
each of the eight subjects participated in a total of two trials : one np trial ( walking 
 without using a trekking pole ) , and one tp trial ( walking using a trekking pole ) . with the 
 treadmill angle set to a decline of 15% based on a study by perrey and fabre12 ,
the participants were subjected to 30 
 minutes of walking at an exercise intensity of 50% of their heart rate reserve .
the 
 experiment used a crossover design to minimize the adaption from the repetitive exercise 
 trials , and each trial was separated by 7 days to avoid any transient effects on the 
 physiological and psychological conditions of the subjects .
an adjustable - length trekking 
 pole ( 6342011 ; leki , hamburg , germany ) was used , and the length was initially set at 70% of 
 the user s height so that the elbow angle was maintained at 90 when the user was standing 
 on level ground . when the pole was used for downhill walking ,
its length was increased by 
 approximately 5  cm . using a 22-gauge needle ,
a serum separator tube ( becton dickinson , franklin lakes , nj , 
 usa ) , and a ethylenediamine tetra - acetic acid tube ( becton dickinson ) , 7  ml of blood was 
 collected from the antecubital vein of each subject at the pre - walking baseline ( pwb ) , 
 immediately after walking ( iaw ) , and 2 hours post - walking ( 2hpw ) . collected blood samples 
 were centrifuged for 15 minutes at 3,000  rpm and then stored at 80  c until analysis .
the 
 serum ck and ldh levels were determined using a clinical chemistry analyzer ( ektachem 
 dtscii ; eastman kodak , rochester , ny , usa ) .
the serum comp levels were determined with an 
 enzyme - linked immunosorbent assay ( elisa ) using a commercially available human 
 comp elisa kit ( anamar ab , lund , sweden ) .
the absorbance was measured at 
 450  nm with a microplate reader ( molecular device , palo alto , ca , usa ) .
the plasma lactate 
 levels were determined using a clinical chemistry analyzer ( ektachem dt 60 ; eastman kodak , 
 rochester , ny , usa ) .
data are presented as the mean  standard deviation ( sd ) unless otherwise stated . 
 for identifying differences in normally distributed results ,
when significant group by time interactions occurred , simple 
 main effects were assessed using one - way anova and independent t - tests .
the biomarker levels measured are presented in table 
 1table 1.peripheral biomarkers after downhill walking with the use of trekking poles ( tp ) 
 and without their use ( np)variabletrialpwbiaw2hpwck(u / l)np260.3  39.1349.1  37.9302.9  42.0tp256.1  42.0312.5  44.9270.9 
34.5ldh(u / l)np351.5  77.8453.4  70.6377.0  84.0tp354.9  79.3385.1  71.2363.5  64.6comp(u / l)np9.6  2.013.6  3.812.0  2.8tp9.9  2.213.2  3.610.0 
np : no trekking pole trial ; tp : trekking pole trial ; 
 pwb : pre - walking baseline ; iaw : immediately after walking ; 2hpw : 2 hours post - walking ; 
 * p<0.05 vs. pwb .. the serum ck , serum ldh , serum comp , and plasma lactate levels were 
 significantly increased iaw when compared with those at the pwb in trials np and tp 
 ( p<0.05 ) .
in addition , in trial np , the serum ck , serum ldh , and serum comp levels were 
 significantly increased at 2hpw when compared with those at the pwb ( p<0.05 ) .
np : no trekking pole trial ; tp : trekking pole trial ; 
 pwb : pre - walking baseline ; iaw : immediately after walking ; 2hpw : 2 hours post - walking ; 
 * p<0.05 vs. pwb .
exercise - induced muscle damage increases in situations involving eccentric muscle 
 contractions , such as during downhill walking and/or running4 .
this study 
 measured the levels of serum ck , ldh , and comp to investigate the effect of the use of a 
 trekking pole on muscle and cartilage damage during downhill walking .
the results 
 demonstrated that the levels of ck , ldh , and comp were significantly higher iaw and 2hpw 
 than at the pwb in the case of the np trials . in the case of the tp trials , however , the 
 levels 2hpw were significantly lower than those for the np trials and actually returned to 
 their level at the pwb
. the rationale could be that the use of a trekking pole alleviated 
 the temporary muscle and cartilage damage induced after downhill walking .
this result is in 
 accordance with those of previous studies ; howatson et al . showed significantly lower serum 
 ck levels at 24 hours after mountain climbing in an experimental group that used trekking 
 poles than in the control group , suggesting that the use of trekking poles could alleviate 
 muscle damage during recovery3 . in 
 addition , exercise - induced increases in joint load have been shown to cause a temporary 
 increase in serum comp levels after walking or running by promoting catabolism , in 
 particular , in cartilages such as the articular cartilage in the knee9 , 13 .
bohne and 
 abendroth - smith suggested that the use of a trekking pole during downhill walking could be 
 effective for reducing such loads on the lower extremity joints7 . according to the results of some previous studies ,
the use 
 of a trekking pole could reduce lower limb joint forces by as much as 25% , enabling a 13  kg 
 reduction of load per stride during downhill walking3 , 
 14 .
however , as for the plasma lactate levels in this study , no significant difference was 
 observed with the use of a trekking pole .
the rationale is that although the use of a 
 trekking pole reduced forces on the lower limbs , it increased the activity of the upper 
 limbs and consequently maintained a similar fatigue level in the whole body .
this 
 interpretation is supported by the report that plasma lactate concentration was a biomarker 
 reflecting peripheral muscle fatigue during exercise15 , as well as by the suggestion of fritschi et al . that , although the 
 use of a pole during walking could reduce vertical knee joint forces , it could increase 
 upper limb muscle activation16 . in conclusion ,
downhill walking can cause muscle and cartilage damage , and it is suggested 
 that the use of a trekking pole can reduce temporary muscle and cartilage damage after 
 downhill walking .
 [ purpose ] this study investigated the effect of the use of trekking poles on muscle and 
 cartilage damage and fatigue during downhill walking in obese women . 
 [ subjects and 
 methods ] subjects included eight obese women who had a body fat percentage greater than 
 30 . 
 subjects performed downhill walking without a trekking pole ( np ) and with a trekking 
 pole ( tp ) at 50% heart rate reserve for 30 minutes on a treadmill . the treadmill was set 
 at a 15% downhill declination . 
 blood samples were collected to examine muscle damage 
 ( serum creatine kinase [ ck ] and lactate dehydrogenase [ ldh ] levels ) , cartilage damage 
 ( serum cartilage oligomeric matrix protein [ comp ] levels ) , and fatigue ( plasma lactate 
 levels ) at the pre - walking baseline ( pwb ) , immediately after walking ( iaw ) , and 2 hours 
 post - walking ( 2hpw ) . [ results ] the ck , ldh , comp , and lactate levels were significantly 
 increased iaw when compared with those at the pwb in both trials . 
 in addition , in the np 
 trial , the ck , ldh , and comp levels were significantly increased at 2hpw when compared 
 with those at the pwb . 
 [ conclusion ] downhill walking can cause muscle and cartilage 
 damage , and our results suggest that the use of a trekking pole can reduce temporary 
 muscle and cartilage damage after downhill walking . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION