the restoration of an optimal gait is a major goal in the rehabilitation of stroke 
 patients1,2,3 . several changes in gait are 
 seen after stroke , such as decreased velocity , asymmetrical stance phase and stride length , 
 and so forth4,5,6 . an abnormal gait after a 
 stroke is caused by many physical conditions such as muscle weakness , abnormal muscle tone , 
 and disorders in balance and posture control , which are all detrimental to gait ability7 . recently , many results from studies on the 
 relationship between trunk muscle activity and the gait function of stroke patients have 
 been being reported . the loss of selective trunk control is a major functional deficit in 
 post - stroke patients that leads to abnormal gait parameters8,9,10,11 . trunk exercises have a 
 beneficial effect on trunk functions including the improvement in standing balance and 
 mobility in stroke patients ; they are particularly effective in improving balance , gait , and 
 functional ability12 . in a previous 
 study , it was suggested that trunk performance was significantly related to gait and 
 functional ability in stroke patients13 . aquatic therapy has also been suggested as an effective approach to improve trunk 
 activity14 . there are many studies on 
 the effect of trunk exercise on gait ability in stroke patients that did not consider the 
 exercise environment . however , comparative studies between aquatic trunk exercise and 
 land - based trunk exercise have rarely been conducted . therefore , the purpose of the present 
 study was to compare aquatic trunk exercise and land - based trunk exercise on the 
 effectiveness of trunk exercise program on gait ability in hemiplegic stroke patients . the participants of this study were 28 hemiplegic stroke patients ( 20 males and 8 females ) 
 who received a diagnosis of stroke and were either admitted to or were receiving treatment 
 at the outpatient center . patients were randomly allocated to either the aquatic exercise 
 group ( 13 patients ) or the land - based exercise group ( 15 patients ) by drawing lots . the 
 inclusion criteria were ( 1 ) a history of only one cerebrovascular accident , ( 2 ) a 
 mini mental state examination ( mmse ) score>24 points , ( 3 ) the ability to walk 
 independently , ( 4 ) no significant musculoskeletal conditions ( fracture , back pain , and so 
 forth ) , and ( 5 ) no contraindications to participation in the exercise program5 , 6 . the aquatic exercise group participated in concentrated aquatic therapy for four weeks 
 ( 30  min sessions for 3 days / week ) in a therapeutic pool with a water depth equal to the 
 xiphoid process and a water temperature of 30  c15 . the aquatic therapy program was based on halliwick , watsu , and 
 trunk exercise programs . the main objective of the program was to improve trunk muscle 
 activation in stroke patients . the program included warm - ups , trunk - specific exercises , and 
 cool - down periods16 , 17 . the warm - up period ( 5  min ) consisted of trunk control with a 
 hallwick 10-point program including exercises for sagittal rotation control , transversal 
 rotation control , longitudinal rotation control , and combined rotation control12 . the trunk exercise period ( 20  min ) 
 consisted of abdominal hollowing , abdominal bracing , anteroposterior pelvic tilts , and 
 mediolateral pelvic tilts18 . finally , the 
 cool - down period ( 5  min ) consisted of a hallwick 10-point program ( sagittal rotation 
 control , transversal rotation control , longitudinal rotation control , and combined rotation 
 control ) and watsu techniques for muscular relaxation and stretching19 , 20 . the aquatic 
 therapy program was conducted by physiotherapists who had participated in a certified 
 halliwick and watsu therapy course . the land - based exercise group performed exercise three 
 times a week for one month . the exercise included 3 sets held for 5 seconds , each maintained 
 for about 30 minutes with a 1-minute rest between sets . the trunk exercises consisted of six 
 subparts : bridge exercises , curl - ups with arms crossed , curl - ups with straight reaching , 
 curl - ups with diagonal reaching , abdominal hollowing , and quadruped exercises21,22,23,24,25 . both knees were flexed at 90 and the feet were hip - width apart while 
 resting on the floor . arms were crossed over the chest to minimize arm support , and the 
 therapist placed his hands vertically along the lateral aspect of the bilateral knee joint 
 to maintain a hip abduction of 30. the subject was instructed to lift his or her pelvis 
 comfortably at a self - selected speed while the trunk , pelvis , and thigh were aligned in a 
 straight line . this position was then held for 5 seconds21 , 22 . the curl - up exercise 
 consisted of three parts : shoulder curl - ups with the arms crossed , curl - ups with straight 
 reaching , curl - ups with diagonal reaching , and shoulder curl - ups with the arms crossed . the 
 knees were flexed at 90. for the curl - up exercise , the subject elevated the trunk until the 
 scapular lifted from the mat22 . for 
 abdominal hollowing , the participant was instructed to draw the lower part of the abdominal 
 up and in toward the spine without moving the trunk or pelvis . a pressure biofeedback unit 
 ( tn37343 , chattanooga group , inc . , usa ) was used to ensure that the subjects were performing 
 the exercise correctly . a pressure cuff unit was placed under the lumbar spine and was 
 inflated to 40 mmhg before the exercise was performed . when the subject performed the 
 hollowing correctly , the pressure either stayed at 40 mmhg or decreased , and the subjects 
 tilted until the abdomen was hollow . this position was then held for 5 seconds23 , 24 . for the quadruped exercise , the participant was initially positioned 
 in a 4-point stance with the knees and hands on the floor with hips flexed to 90 and hands 
 beneath the shoulder joint . in a 2-point stance the subject flexed the arm until the lower body segment was parallel to the 
 trunk . gait ability was measured using a motor - driven treadmill ( gait 
 trainer 2 analysis system inc , america , biodex medical systems ) , which was adjusted to each 
 subject s comfortable walking speed5 , 6 . this equipment can analyze walking factors 
 such as walking speed , walking cycle , affected side stance phase , affected side stride 
 length , symmetry index of stance phase , and symmetry index of stride length through a sensor 
 installed on the treadmill floor5 , 6 . statistical analyses were conducted using 
 pasw software ( version 18.0 ; spss , quarry bay , hong kong ) to calculate averages and standard 
 deviations . the data are expressed as the mean  standard error ( se ) of the measurements . a 
 paired t - test was conducted to compare the participants before and after the trunk exercise . the protocol for this study was 
 approved by the committee of ethics in research of the university of yongin , in accordance 
 with the terms of resolution 5 - 1 - 20 . furthermore , all volunteers or their next of kin 
 provided informed consent for participation in the study . table 1table 1.general characteristics of the participantsvariableexercise environmentaquatic trunk exerciseland - based trunk exerciseage ( yrs)50.5  2.937.9  4.4gendermale ( % /%)10 ( 76.9/35.7)10 ( 66.7/35.7)female ( % /%)3 ( 23.1/10.7)5 ( 33.3/17.9)height ( cm)166.4  1.9168.9  2.2weight ( kg)66.6  2.968.6  3.3bmi ( kg / m)24.0 0.823.9  0.8caused of strokeinfarction ( % /%)10 ( 76.9/35.7)9 ( 60.0/32.1)hemorrhage ( % /%)3 ( 23.1/10.7)6 ( 40.0/21.4)paretic sideright ( % /%)10 ( 76.9/35.7)7 ( 46.7/25.0)left ( % /%)3 ( 23.1/10.7)8 ( 53.3/28.6)onset ( mo)24.1  3.817.2  2.2k - mmse ( score)24.9  0.425.3 bmi : body mass index , k - mmse : korean 
 version of the mini - mental state examination shows the general and clinical characteristics of the 28 stroke patients . 
 walking speed and cycle , stance phase and stride length of the affected side , and the 
 symmetry index of the stance phase significantly improved after the aquatic and land - based 
 trunk exercise program ( table 2table 2.changes after four weeks of trunk exercise program in hemiplegic stroke 
 patientsvariableexercise environmentaquatic trunk exerciseland - based trunk exercisepre - ateppost - ateppre - lteppost - ltepwalking speed ( cm / sec)51.4  5.157.9  7.046.5  2.352.6  2.3walking cycle ( cycle / sec)0.4  0.00.4  0.00.6  0.00.6  0.2affected side stance phase ( sec/%)36.2  4.246.5  3.037.0  2.441.6  2.4affected side stride length 1.5symmetry index of stance phase ( % ) 62.6  12.484.2  9.062.2  6.675.0  7.7symmetry index of stride length ( % ) 92.9  5.597.0  5.7108.6  6.1103.0 atep : aquatic trunk exercise program ; ltep : 
 land trunk exercise program ; * paired t - test between pre- and post - treatment . bmi : body mass index , k - mmse : korean 
 version of the mini - mental state examination all data are presented as the mean  se . atep : aquatic trunk exercise program ; ltep : 
 land trunk exercise program ; * paired t - test between pre- and post - treatment . 
 independent t - test between groups . the loss of trunk control is a major functional deficit that causes gait disturbance in 
 stroke patients . previous studies have reported that trunk performance remains impaired 
 after a stroke , which is detrimental to balance , gait , and functional ability , highlighting 
 the importance of trunk rehabilitation13 . other studies have found that trunk flexor and extensor muscle weakness correlates with berg 
 balance scale scores and locomotion and transfer items of the functional independence 
 measure26 . our study demonstrated the 
 effects of four weeks of trunk exercise in aquatic and land - based environments on gait 
 parameters . according to our data , gait parameters were improved in both groups despite the 
 short period of intervention . a slow pace and asymmetric gait are most common problems in 
 gait in stroke patients12 . many previous 
 studies have suggested that the most important parameter to target in stroke patients is 
 walking speed12 . perry suggested that 
 gait velocity is a useful indicator that represents clinical trends , gait quality , and the 
 degree to which gait velocity is abnormal in both hemiplegic stroke patients and healthy 
 patients12 . in addition , velocity is 
 easy to measure and is closely related to the patient s clinical condition . however , an 
 increase in gait velocity without improvement in symmetry suggests that compensatory 
 strategies are retained and amplified . therefore , improvements in gait velocity in stroke 
 patients should be accompanied with improvements in symmetry27 . according to our data , participants in both groups had improved 
 walking speed and improved stance phase and stride length of the affected side . some gait 
 parameters differed between the baseline and posttreatment ; however , the changes were not 
 significant . as a result , our data demonstrated that trunk exercise improves the gait 
 ability of stroke patients irrespective of the environment . previous studies on the 
 relationship between gait ability and trunk exercise have demonstrated the effectiveness of 
 trunk exercise using various tools , but these tools were insufficient for the analysis of 
 gait parameters in stroke patients . our study used gait trainer 2 , which analyzed gait 
 parameters by a sensor installed on the treadmill s floor , similar to the gaitrite system . these methods were proven by many studies to be adequately assess gait parameters in 
 hemiplegic stroke patients . further , our results concur with those of previous studies 
 evaluating the gait trainer system for measuring gait parameters in stroke patients22,23,24 . according to previous studies , therefore , we sought to examine aquatic 
 trunk exercises as an effective method to improve gait ability in patients who experienced 
 difficulty controlling the trunk . both trunk exercises in water and on land - based 
 were found improve gait parameters in stroke patients . however , further systematic and 
 scientific studies in neurorehabilitation and other fields are needed to confirm the effects 
 of therapy28 , 29 .
[ purpose ] the purpose of this study was to compare the effects of aquatic and land - based 
 trunk exercise program on gait in stroke patients . 
 [ subjects and methods ] the subjects 
 were 28 hemiplegic stroke patients ( 20 males , 8 females ) . 
 the subjects performed a trunk 
 exercise program for a total of four weeks . 
 [ results ] walking speed and cycle , stance 
 phase and stride length of the affected side , and the symmetry index of the stance phase 
 significantly improved after the aquatic and land - based trunk exercise program . 
 [ conclusion ] these results suggest that the aquatic and land - based trunk exercise program 
 may help improve gait performance ability after stroke .