as our society has become an aging society , improving the quality of life has become one of 
 the major interests in it . impaired balance and gait abilities due to aging and diseases therefore , it is clear that 
 balance problems can directly affect the quality of our lives . the physical activities of 
 the elderly can be improved by diverse exercise programs and activities . it is important to 
 perform stretching before exercises to prevent injuries and enhance exercise in a more 
 efficient way1 . the common type of 
 stretching is static stretching , and the effect of stretching may vary with the type 
 applied , intensity , and time2 , 3 . while stretching has positive effects ( e.g. , increases rom , 
 injury prevention , and improvement in the ability to perform exercises)3 , negative effects ( e.g. , temporary decreases in maximum 
 muscle power and stretch - induced impairment in reaction time and movement time ) can appear 
 immediately after stretching4,5,6 . in reality , some 
 elderly individuals complain of temporary difficulties in balance control immediately after 
 pss . however , previous studies have been limited to the acute effects of stretching in terms 
 of the histological and neurological changes during or after stretching7,8,9,10 . furthermore , only a few 
 studies have examined the temporary difficulties in balance and gait of elderly populations 
 after stretching . therefore , the purpose of this study was to examine the acute effects of 
 stretching on balance and gait in the elderly . twenty - five community - dwelling elderly subjects voluntarily participated in this study 
 under the following criteria : at least 65  years of age , no experience of falls in a year , 
 able to walk at least 10  m independently without a walking aid or another person s help , and 
 a mini mental state examination - korea ( mmse - k ) score exceeding 24 points . those who had any 
 particular disease that could affect their performance such as vision or hearing damage , or 
 any problems in their nervous systems , vestibular organs , or understanding the contents of 
 the experiment were excluded . all included patients understood the purpose of this study and 
 provided written informed consent prior to participation in the study in accordance with the 
 ethical standards of the declaration of helsinki ( table 
 1table 1 . general characteristics of subjectsgender ( m / f)1/24age ( years)79.1  6.2height ( cm)150.1  6.6weight ( kg)54.1  7.5mmse - k ( point)25.6  1.5*p < 0.05 ( mean  sd ) . mmse - k : mini mental state examination - korea each subject performed pss for 5 minutes on a wedge board with an attached nonslip mat on 
 its contact surface . subjects were instructed to maintain an upright posture while keeping 
 their arms to their sides and looking straight ahead . the angle of inclination of the wedge 
 board was adjusted to an angle ( 1525 ) at which the subject did not feel uncomfortable . to 
 examine the changes in balance and gait following the application of 5  min of pss , sway 
 lengths during quiet standing for 1  min were measured and functional reach tests ( frts ) , 
 timed up and go tests ( tugs ) , and timed 10-meter walk tests ( 10mwts ) were implemented . to 
 examine the subjects static balance ability , each of the subjects was instructed to stand 
 on a biorescue ( rm ingenierie , rodez , france ) for 1  min with their feet shoulder width apart 
 and eyes closed while the sway length of the center of mass was measured . in the frts , the 
 subject was asked to stand with their bare feet shoulder width and to reach forward with 
 both arms as far as possible without taking a step or touching the wall . the distance 
 between the start and end point was measured . in the tugs , the time required for the 
 subjects to complete the following task was measured : rising from a chair , walking 3 m , 
 turning around , walking back to the chair , and then sitting down on the same chair . in the 
 10mwts , the subject was asked to walk 10  m without any aids , and the time required to walk 
 the 6  m in the middle was measured ; the first and last 2-m sections were excluded to account 
 for the accelerating and decelerating phases . the frts , tugs , and 10mwts were repeated three 
 times by each subject , and the best records were used . after stretching , the sway distance of the center of mass during 1  min of quiet standing 
 without visual information increased significantly ( by 6.55  5.03  cm ; p < 0.05 ) . however , no statistically significant difference was shown in the frts , tugs , or 10mwts 
 measured 1  min later ( p > 0.05 ; table 
 2table 2 . comparison of balance and gait after 5  min of plantar flexor static 
 stretchingvariablepre ( mean  sd)post ( mean  sd)sway length ( cm)38.4  15.144.9  17.1*frt ( cm)20.3  8.518.1  7.3tug ( sec)10.3  1.810.0  1.910mwt ( sec)7.6  2.17.2  1.6 * p < 0.05 ( mean  sd ) . sway length : sway length for 1 minute ; frt , functional 
 reach test ; tug , timed up and go test ; 10mwt , timed 10-meter walk test ) . * p < 0.05 ( mean  sd ) . sway length : sway length for 1 minute ; frt , functional 
 reach test ; tug , timed up and go test ; 10mwt , timed 10-meter walk test pss is frequently used for warming up or cooling down in exercise programs to reduce ankle 
 stiffness , improve joint mobility , or increase physical activity1 . this study was conducted to examine the acute effects of 
 5  min of pss on balance and gait in the elderly after stretching . the results showed that 
 despite the temporary increase in postural sway distance immediately after stretching , the 
 subjects recovered their dynamic balance and gait abilities after a short period of 
 rest . the duration of stretching can also affect balance . although stretching for a short time 
 resulted in improvement of balance by promoting muscle activity11 , stretching for a long time adversely affected 
 balance6 , 12 . ( 2009 ) stated that whereas 15 seconds of stretching 
 improved balance , 45 seconds of stretching did not affect balance11 . ( 2006)12 and yuk ( 2012)6 , in which longer pss was used , reported that postural sway 
 lengths increased after 3 minutes and 15 minutes of static stretching . in this study , the 
 sway lengths during quiet standing for 1  min immediately after the application of 5 minutes 
 of stretching increased compared with before stretching . static stretching may alter the mechanical and neurologic characteristics of the calf 
 muscle13 , 14 . nakamura et al . reported that the passive torque of the 
 gastrocnemius and the displacement of the myotendinous junction significantly changed at the 
 2- , 3- , and 4-min points with 5  min of pss15 . behm et al . reported that reaction / movement time for regaining 
 balance increased after 45 seconds of stretching4 . therefore , the temporary increase in the sway length immediately 
 after stretching shown in this study is attributed to the mechanical and neurologic changes 
 caused by stretching . however , in the frts , tugs , and 10mwts implemented to examine the 
 subjects dynamic balance and gait abilities , the reach distance and gait time did not show 
 any significant difference compared with before stretching . similarly , stretching studies conducted with stroke patients did not 
 show changes in walking speed after pss16 , 17 . limitations of the present study include not only the small sample size but also the fact 
 that stretching exercises under diverse conditions were not compared with each other . although the elderly subjects experienced temporary difficulties in maintaining balance 
 after 5  min of pss , their dynamic balance and gait were not affected when a recovery time of 
 approximately 1  min had passed . the authors of this study recommend that elderly individuals 
 take a brief rest after pss before walking or activities in exercise programs to prevent 
 falls and perform exercises safely .