more than half of those disabled by a stroke have difficulty in walking or can not walk 
 within 3 months following stroke onset1 . maximally , 70% of them recover to normal walking within 1  year , 4560% can walk without help 
 but have a disability , and 59% have gait disturbance necessitating complete reliance on 
 others2 . thus , the biggest goal of 
 stroke patients is to improve walking function3 . to improve ambulatory function , gait training using a treadmill although studies have analyzed the movement of the upper body during walking5,6,7 , most studies investigating the body s 
 forward movement ability while walking have focused on physical intervention for the lower 
 body , such as loading weight on the paretic limb of stroke patients doing standard treadmill 
 exercise8,9,10 , or underwater treadmill 
 gait training11 . most studies focusing on 
 physical intervention for the upper body have applied a horizontal force to the waist area 
 while subjects , including athletes , walked or ran12,13,14,15,16,17,18 . however , few studies have sought to determine changes in ambulation and balance resulting 
 from physical intervention for the upper body of stroke patients . this study examined the effect of gait training on walking ability ( stable walking speed , 
 maximal walking speed , number of steps per minute , and stride ) and balance ( timed up and go 
 test [ tug ] , berg balance scale [ bbs ] , and functional reach test [ frt ] ) of stroke 
 patients . the subjects were 24 stroke patients who visited the national rehabilitation center and 
 received exercise treatment . of the stroke patients who had experienced their first stroke 
 within the previous 3 months , we selected those who ( 1 ) had scores of > 3 on the 
 functional ambulation category ( fac ) , indicating they could walk independently under 
 observation ; ( 2 ) had scores of > 24 in the mini - mental state examination korea ( mmse - k ) , 
 indicating they could communicate ; ( 3 ) did not have other orthopedic diseases , acute pain 
 affecting walking , or progressive neuropathy ; ( 4 ) did not take drugs that might have 
 influenced balance ability ; and ( 5 ) provided their written consent after receiving 
 explanation of the research purpose ( table 
 1table 1.general and clinical characteristics of the subjectsdistributionhif group(n = 12)control group(n = 12)male ( n)89female ( n)43right side ( n)68left side ( n)64hemorrhage ( n)85infarction ( n)47age ( years)51.3  7.352.92  8.3height ( cm)166.7  6.7165.25  6.3weight ( kg)63.8  6.967.50  5.1disease duration ( months)5.42  1.675.17  1.6fac ( score ) : 386fac ( score ) : 446mmse - k ( score)26.0  2.027.0  2.2hif : horizontal impeding force , fac : functional ambulation category , mmse - k : 
 mini - mental state examination korea . hif : horizontal impeding force , fac : functional ambulation category , mmse - k : 
 mini - mental state examination korea . values are presented as mean  sd all experimental protocols and procedures were explained to each subject and approved by 
 the institutional review board of the national rehabilitation center , korea 
 ( nrc-2011 - 02 - 005 ) . the subjects were assigned to a treadmill walking group with a horizontal impeding force 
 ( hif ) and a control group . before the intervention a pre - test was conducted to determine the 
 subjects maximal walking speed , stable walking speed , stride , number of steps per minute , 
 tug , bbs and frt . a 
 physical therapist oversaw the treadmill gait training and treadmill test at the national 
 rehabilitation center , and the author and an assistant performed the pre - test and final 
 assessment . during training , the hif group and the control group wore harnesses for safety , which was 
 the first priority . the 
 gradient during gait training was 0 , and a physical therapist provided oral instructions for 
 foot position when needed . subjects received a detailed explanation of the borg ( 1970 ) 
 15-point scale ( rating of perceived exertion [ rpe ] scale , 620 points ) . to determine each 
 subject s rpe , they were asked to indicate the relevant number ( 620 ) on a korean language 
 borg scale orally or with their finger . the test was started at a speed at which the 
 subjects felt safe , then the treadmill speed was slowly increased . the standard of feeling 
 of safety was the level of comfort or an average rpe of 911 points while walking on the 
 treadmill for 3 minutes . when if required , 5 minutes were allowed to adapt to the treadmill 
 speed before the training . the walking speed of the second training was carried out by 
 increasing or reducing the speed until an rpe of 911 points was achieved , based on the 
 treadmill walking speed of the first step . tests were started after subjects consented to 
 undergo treadmill training for 20 minutes per day , 3 times per week , for 8 weeks . hif subjects received hif against the center of gravity of the upper body while walking at 
 a pre - measured speed . the hif applied was within 015% of subject measured body weight16 , and the treadmill speed was set at a 
 speed corresponding to an rpe of 911 points , which is the level of comfort or average on 
 the borg scale . the first training session was performed with minimal pulling capacity 
 ( 1  kg ) , at a pre - measured comfortable walking speed . in the second hif training session , the 
 speed was set so that an rpe of 911 points was maintained for 3 minutes . when necessary , % 
 minutes were allowed to adapt to the treadmill speed and hif before the training . if 
 subjects expressed a desire to continue the test after the adaptation time , training was 
 carried out at the prescribed walking speed and hif . for the third training bout , a rpe of 
 911 points was the target , and hif was adjusted accordingly . the cable can be loaded in 
 1  kg units from 0 to 50  kg , and it is possible to adjust its height in 10  cm intervals from 
 14  cm to 225  cm . also cables are available in a range of up to 3  m. in this study , because we applied backward traction during the treadmill training , a shuma 
 da-3000 harness was worn by the subjects to prevent falls . the mt- 400 treadmill has the same features as a general treadmill as well as a primary and 
 emergency power - off device that can be operated by user . when users press the button on the 
 handle the treadmill is stopped therefore , this device was used in consideration of safety 
 and the prevention of accidents . the paired t - test was 
 used to verify differences in the pre- and post - test mean values of maximal walking speed , 
 stable walking speed , stride , number of steps per minute , tug , bbs , and frt in each group . the independent t - test was used to verify differences between the hif group and the control 
 group . compared to their pre - test values , the post - test values of stable walking speed , maximal 
 walking speed , number of steps per minute , and stride significantly increased in both groups 
 ( p < 0.05 ) . there were greater differences in the hif group than in the control group ( p 
 < 0.05 ) . compared to their pre - test values , the post - test values of tug and bbs significantly 
 increased in both groups ( p < 0.05 ) , and there were greater differences in the hif group 
 than in the control group ( p < 0.05 ) . the main finding of the present study was that a treadmill walking training program 
 improved stable walking speed , maximal walking speed , number of steps per minute , and 
 stride . while there are some small discrepancies between reports in the elapsed time and walking 
 speed after stroke , it has generally been reported to be within the range of 0.250.5 
 m / s21 . the pre - training stable walking 
 speeds of the present study were consistent with this range . robinett and vondran22 suggested 0.5 m / s 
 as the lowest possible walking speed on a road in general . perry , garrett , granley , and 
 mulroy23 suggested 0.8 m / s as a speed 
 enabling functioning and independent action in various environments and social settings . a 
 walking speed sufficient to cross roads at traffic lights in a business area that does not 
 affect social life compared to these values , the present 
 research reports speeds that , though they may have a small effect on social functioning , 
 enabled the patient to walk safely , independently , and without great inconvenience for 
 stable social activies . table 2table 2.results of stable walking speed , maximal walking speed , number of steps per 
 minute , and stridehif groupcontrol groupstable walking speed ( sec/10 m)before20.93  5.6119.84  10.62after11.83  3.7015.73  8.40difference9.10  4.714.11  3.78maximal walking speed ( sec/10 m)before14.39  3.0914.13  7.23after9.61  2.7511.73  6.24difference4.78  2.692.39  2.15number of steps per minute ( step / min)before84.62  15.0487.02  17.74after102.54  21.0693.77  20.58difference17.91  13.736.75  9.88stride ( cm)before34.26  8.5741.97  14.71after53.70  8.8847.98  12.61difference19.44  10.216.01  6.12values are presented as mean  sd . significant difference , paired t - test : 
 * : p<0.05 ; * * : p<0.001 ; * * * : p<0.0001 . significant difference , independent 
 t - test : : p<0.05 ; : p<0.001 shows that the number of steps per minute and stride significantly improved in 
 both groups after training . this provides evidence that treadmill gait training is a very 
 effective way of improving walking ability . moreover , the number of steps per minute and 
 stride significantly increased in the hif group compared to the control group , suggesting 
 that adding hif to the center of gravity of the upper body during treadmill training more 
 effectively improves walking ability than treadmill training alone and is a very effective 
 way of improving gait training . significant difference , paired t - test : 
 * : p<0.05 ; * * : p<0.001 ; * * * : p<0.0001 . significant difference , independent 
 t - test : : p<0.05 ; : p<0.001 it has been reported that both the number of steps per minute ( r = 0.75 ) 
 and stride ( r = 0.78 ) are highly correlated with walking speed24 , suggesting that walking speed in the 
 present report increased due to the significantly increased number of steps per minute and 
 stride . this further suggests that the subjects could walk more stably , at a brisker pace , 
 in longer strides , for a greater number of steps , and over a greater distance , than before 
 training . choi , lee , and jang25 reported that 
 improvements in walking speed were mostly due to an increase in strides . considering that a 
 slow walking speed increases the risk of accidental falls , improving walking speed could 
 help prevent accidental falls as well as improve walking ability . therefore , as walking 
 speed and stride increased more when hif was applied to the upper body during treadmill gait 
 training , it suggests that adding of hif to gait training is a more effective way of 
 improving walking ability and preventing accidental falls . to test the effecacy of treadmill training , with or without hif , on balance ability , tug , 
 bbs , and frt were measured . the results show that both groups showed significant 
 improvements in tug , bbs , and frt after training , compared with before training , providing 
 evidence that treadmill gait training is a very effective way of improving dynamic and 
 static balance abilities ( table 3table 3.changes in tug , bbs , and frthif groupcontrol grouptug ( sec)before21.85  3.7518.17  8.05after14.42  2.8515.12  7.42difference7.42  3.333.04  2.27bbs ( points)before40.83  3.2742.58  7.53after50.50  3.1147.00  7.50difference9.66  3.864.41  2.50frt ( cm)before24.35  5.5420.69  9.12after30.96  5.6227.29  7.92difference6.60  6.106.6 hif : horizontal impeding force , tug : 
 timed up and go test , bbs : berg balance scale , frt : functional reach test . significant 
 difference , paired t - test : * : p<0.05 ; * * : p<0.001 ; * * * : p<0.0001 . significant 
 difference , independent t - test : : p<0.05 ; : p<0.001 ) . hif : horizontal impeding force , tug : 
 timed up and go test , bbs : berg balance scale , frt : functional reach test . significant 
 difference , paired t - test : * : p<0.05 ; * * : p<0.001 ; * * * : p<0.0001 . significant 
 difference , independent t - test : : p<0.05 ; : p<0.001 podsiadlo and richardson26 reported that 
 a tug time < 10 seconds in the elderly aged 6090  years indicates functional freedom and 
 independence ; > 10 seconds to < 20 seconds indicates independent movement for a basic 
 bath or shower , and the ability to go up most stairs and out by themselves ; if it takes > 
 13.5 seconds , the risk of fall increases ; if > 30 seconds , most activities are dependent . these results suggest that treadmill gait training is an effective way of reducing the risk 
 of fall , particularly as the tug time of the hif group decreased from a mean of 21.85 
 seconds to 14.35 seconds . this suggests that it is an effective way of training which 
 considerably reduces the risk of fall and enables activities of daily living such as a bath 
 or shower and going out alone . along with a study27 reporting that if 
 bbs was > 41 points , the possibility of fall was low , kornetti , fritz , chiu , light and 
 velozo28 reported that if bbs > 45 
 points , independent safe walking was possible . our present results show that the bbs scores 
 of both groups were > 45 points and improved following training . thus , it is evident that 
 treadmill gait training is an effective way of training for independent safe walking . thus , treadmill gait training with 
 hif applied to the center of gravity of the upper body is a more effective way of training 
 for independent , safe ambulation . future research on hif during gait training for stroke patients needs to examine the height 
 at which applying the pulling power can generate the optimal effect , the optimal amount of 
 hif , and the muscle activity most influenced by hif during treadmill gait training and gait 
 training , as long as safety is guaranteed . horizontal aiding force is another factor that studies should consider , and comparisons of 
 the effects of hif and horizontal aiding force on the walking ability and balance of stroke 
 patients are necessary .
[ purpose ] the purpose of this study was to investigate the effects of treadmill training 
 with a horizontal impeding force applied to the center of upper body mass on the gait and 
 balance of post - stroke patients . 
 [ subjects and methods ] twenty - four subjects with 
 hemiplegia less than 3 months after stroke onset were randomly assigned to 2 groups : an 
 applied horizontal impeding force on treadmill training ( experimental ) group ( n = 12 ) , and 
 a control group ( n = 12 ) . both groups walked on a treadmill at a comfortable or moderate 
 speed for 20 minutes per day , 3 sessions per week for 8 weeks after a pre - test . 
 the 
 experimental group also had a horizontal impeding force applied to the center of their 
 upper body mass . 
 [ results ] all groups demonstrated significant improvement after 8 weeks 
 compared to baseline measurements . in intra - group comparisons , the subjects gait ability 
 ( cgs , mgs , cadence , and step length ) and balance ability ( tug , bbs , and frt ) significantly 
 improved . in inter - group comparisons , 
 the experimental group s improvement was 
 significantly better in cgs mgs , cadence , step length , tug , and bbs , but not in frt . 
 [ conclusion ] treadmill training was identified as an effective training method that 
 improved gait and balance ability . 
 a horizontal impeding force applied during treadmill 
 training was more effective than treadmill walking training alone at improving the gait 
 and dynamic balance of patients with stroke .