balance is important for the young and the old , and in the elderly , impaired balance has 
 been associated with reduced functional ability and an increased risk of falls1 , 2 . 
 balance has been defined as the ability to maintain one s equilibrium when one s center of 
 gravity shifts ( dynamic balance ) , as in walking and running , and when one s center of 
 gravity remains stationary ( static balance ) , as during standing or sitting3 . several neural and biomechanical factors 
 work together to achieve balance , especially the visual , vestibular , and somatosensory 
 systems4 . preventive exercises are most commonly used to reduce the risk in elderly individuals with 
 declining balance ability . in addition , since trunk muscle strength in the elderly is much 
 weaker than limb muscle strength , function improvements in the lumbar region enhance overall 
 body function , improve balance and walking ability , and reduce fall risks5 . swiss ball exercise is used as a rehabilitative tool to correct posture and to treat and 
 prevent pain in the neck and waist , because it can increase muscle strength , endurance , 
 flexibility , and coordination and be used to improve perceptual balancing ability . trunk 
 stabilization exercises with a swiss ball can also improve core muscle activation and 
 physical functions , because it enhances balance sense and ability by powerfully stimulating 
 proprioceptors6 , 7 . exercises conducted on uneven surfaces , such as a swiss ball , can generate more activity 
 than exercises on even surfaces and are effective for preventing musculoskeletal damage by 
 improving dynamic balance8 , 9 . according to seo et al.10 , swiss ball 
 exercises effectively improve balance ability in elderly women , and song et al.11 reported that swiss ball and resistance 
 exercises can improve the balance abilities of scoliosis patients . however , most exercises are performed without blocking vision , which has been shown to have 
 great effects on the ability to balance while standing12 . however , little research has been conducted to determine the 
 effects of blocking vision on the ability to balance during balance exercises performed with 
 a swiss ball . therefore , we investigated the effects of balance exercises with a swiss ball 
 on static and dynamic balance abilities . this study was conducted on 20 elderly people living in community homes in d city , south 
 korea . the study selection criteria applied were as follows : ( 1 ) 65  years old , ( 2 ) no falls 
 within the previous year , ( 3 ) the ability to walk independently for more than 10  m without 
 an ambulatory assistive aid or an assistant , and ( 4 ) the absence of any disease that might 
 affect test results . those with a visual impairment , hearing damage , or a nervous system or 
 vestibular organ problem and those who were unable to understand the nature of the 
 experiment were excluded . all subjects were given information on the study , and all provided 
 written informed consent prior to participation in accordance with the declaration of 
 helsinki . after completing initial assessments , the 20 subjects were randomly assigned to an 
 experimental group ( n=10 ) or a control group ( n=10 ) using 
 preprepared sealed envelopes containing the letters a or b , which indicated the experimental 
 and control groups , respectively . the subjects performed trunk stabilization exercises with a swiss ball for 20 minutes , five 
 times per week for 4 weeks . trunk stabilization exercises were carried out using a 
 professional exercise ball ( thera - band , the hygenic corporation , akron , oh , usa ) . ball 
 diameters were chosen on an individual basis so that the subjects heels could comfortably 
 touch the ground when sitting on the ball . one set of trunk stabilization exercises was composed of ten repetitions of five different 
 routines . ten sets were completed in each exercise session with a two - minute break between 
 sets . first , a subject was asked to sit on a ball while lifting one or both arms . second , 
 the subject sat on the ball with the feet ( soles and heels ) on the ground while bending the 
 hip and knee joints at 90-degrees , and was then asked to maintain the trunk in an upright 
 position for 20 seconds . third , the subject performed pelvic tilt ( anterior / posterior , 
 left / right ) and rotation exercises . fourth , the subject placed the ball under his / her trunk 
 while in a four - point kneeling position and lifted the arms and legs in the following 
 manner : right arm with left leg and then left arm with right leg consecutively for five 
 seconds . fifth , with the subject in the prone position , the ball was placed beneath the feet 
 and the hips were lifted for five seconds . during these exercise routines , the experimental 
 group was blindfolded , but the control group was not . balance ability was assessed using times taken to perform routines and using distances 
 moved from left to right or forwards and backwards , and balance ability scores were 
 evaluated using a good balance system ( nce gb8300 , metitur , finland ) . the subjects stood on 
 the foothold of the device and practiced three times to ensure that the test could be 
 performed properly , and three repetitive measurements were averaged13 . intergroup differences in general characteristics before the intervention were compared 
 using the independent t - test . intragroup comparisons of variables before and after the 
 intervention were performed using the paired samples t - test . intergroup comparisons of pre- 
 to post - intervention differences in were performed using the independent t - test . , amonk , ny , usa ) was used for statistical analysis , and p 
 values of < 0.05 were considered significant . the experimental group showed significant post - intervention improvements in velocity in 
 examination of static balance and in time , total distance , and left / right movement distance 
 in examination of dynamic balance ( p<0.05 ) , whereas the control group achieved 
 significant improvements in time in examination of dynamic balance ( p<0.05 ) . furthermore , 
 post - intervention gains in velocity were significantly greater in the experimental group 
 ( p<0.05 ) ( tables 1table 1.post-intervention static balance changes in the experimental and control groups 
 ( values are presented as means [ standard deviations])egcgprepostprepostlt / rt velocity ( mm / s)5.1  3.34.8  1.94.9  1.24.9  1.9ant / post velocity ( mm / s)6.3  2.96.1  1.27.2  1.17.3  1.7velocity ( mm / s)18.6  24.911.9  9.115.8  4.314.2  6.1lt / rt length ( mm)155.8  99.5146.0  59.6148.7  36.8149.6  59.8ant / post velocity ( mm)191.1  88.0183.1  38.1217.5  33.4221.5  53.0eg : experimental group ; cg : control group ; ant / post : anterior / posterior ; lt / rt : 
 left / right . significant intergroup difference between the gains achieved , 
 p<0.05 . significant difference from pre - test ( p<0.05 ) and 2table 2.pre- and post - intervention dynamic balance values in the experimental and control 
 groups ( values are presented as means [ standard deviations])egcgprepostpreposttime16.4  5.410.7  2.515.0  6.89.8  2.0total distance ( mm)1.4  4.81.2  4.11.9  0.51.2  8.3lt / rt md ( mm)937.1  415.3782.1  372.41,219.1  1,423.0806.7  290.2ant / post md ( mm)931.2  214.7800.0  182.61,237.4  793.3838.3  167.0eg : experimental group ; cg : control group ; ant / post md : anterior / posterior movement 
 distance ; eg : experimental group ; cg : control group ; ant / post : anterior / posterior ; lt / rt : 
 left / right . significant intergroup difference between the gains achieved , 
 p<0.05 . significant difference from pre - test ( p<0.05 ) eg : experimental group ; cg : control group ; ant / post md : anterior / posterior movement 
 distance ; lt / rt md : left / right movement distance the present study was aimed at examining the effects of 
 trunk stabilization exercises using a swiss ball whilst blindfolded on balance ability in 
 elderly ( 65  years old ) subjects . it was found that both the experimental and control groups 
 achieved improvements in dynamic and static balance abilities . in particular , the 
 experimental group achieved a significantly greater increase in static balance ability than 
 the control group . static balance ability is defined as the ability to maintain one s 
 balance on even surfaces , whereas dynamic balance ability is defined as the ability to 
 maintain one s balance when standing on unstable and/or moving surfaces15 . furthermore , exercising with a blindfold stimulates other 
 senses by blocking visual information , and hence improves balancing ability . in a study 
 conducted by bonan et al.16 , exercise 
 with a blindfold it was found that balance 
 ability was significantly improved , and this was ascribed to reduced reliance on visual 
 information and forced use of somatosensory and vestibular senses . we found that after four weeks of 
 blindfolded balance exercise , balance ability in our elderly cohort improved significantly 
 more than after four weeks of non - blindfolded balance exercise . first , the small sample size 
 may have biased our results , and thus , our findings can not be generalized to all elderly . second , due to the lack of follow - up after the intervention , the durability this 
 intervention could not be determined . third , functional measurements were not performed to 
 determine whether or not a functional benefit was achieved in terms of the activities of 
 daily living . therefore , we suggest that additional studies with long - term follow - up 
 assessments should be performed to evaluate the long - term benefits of trunk stabilization 
 exercise without visual information .
[ purpose ] this study was undertaken to investigate the effects of the balance exercises 
 with a swiss ball on static and dynamic balance abilities in elderly ( 65  years ) subjects . 
 [ subjects and methods ] twenty elderly subjects with no relevant orthopedic history of a 
 back condition were selected for trunk stabilization exercises with a swiss ball 
 ( thera - band , usa ) . 
 the subjects performed these trunk stabilization exercises for 20 
 minutes , five times per week for 4 weeks . 
 the experimental group ( n=10 ) was blindfolded 
 during these balance exercises , while the control group control group 
 ( n=10 ) was not . 
 [ results ] the experimental group showed significant 
 improvements in velocity in the evaluation of static balance and in time , total distance , 
 and left / right movement distance in the evaluation of dynamic balance after the 
 intervention , whereas the control group showed significant improvements in time in the 
 evaluation of dynamic balance . 
 a significant intergroup difference was observed after the 
 intervention for velocity gain . 
 [ conclusion ] exercising with a blindfold stimulates other 
 senses by blocking visual information , and hence it enhances improvements in balance 
 ability .