ascending stairs is a common activity of daily living that is essential for independence 
 and quality of life1 . safe stair climbing 
 demands adequate muscle strength to propel the body up the stairs . in addition , during stair 
 negotiation , trunk movements are important with respect to postural control , since the trunk 
 supports the head and lower extremities by regulating both the amplitude and structure of 
 gait - related oscillations and provides input to the visual and vestibular sensory 
 systems1 . therefore , age - related 
 musculoskeletal changes lead to muscle strength decline and limit both balance and gait2 . to date , self - report questionnaires have 
 been used to assess stair negotiation as a part of functional assessments of older adults . recent research suggests some limitations of using self - report questionnaires to assess 
 stair climbing . for example , the questionnaires can not evaluate the quality of the 
 movements , which is important because difficulty in executing such movements may be a 
 reliable and valid indicator of stair climbing impairments3 . oh - park et al . suggest that the time needed to negotiate three 
 steps is a meaningful measure in clinical settings because the risk of functional 
 deterioration in older adults can be easily assessed by this method4 . in addition , the trunk acceleration ratio has been widely 
 used to assess dynamic balance in older adults1 . therefore , the purpose of this study was to investigate the stair 
 ascending time and trunk acceleration ratio during stair climbing in old - old adult 
 females . a total of 25 older females volunteered for this study and were categorized into two age 
 groups : older adults ( 6574 years ) and old - old adults ( 75  years ) . there were a total of 13 
 adults in the older adults group , with an average age , weight , and height of 71.8  2.7 
 ( mean  sd ) years , 51.1  6.4  kg , and 151.5  3.4  cm , respectively . the old - old adults group 
 comprised 12 adults with an average age , weight , and height of 80.4  4.6  years , 49.0  
 6.7  kg , and 148.9  3.5  cm , respectively . all participants were able to walk independently 
 without the use of any assistive device and all had a score greater than 24 on the korean 
 version of the mini - mental state exam . approval for this study was obtained from the inje 
 university ethics committee for human investigations , and written informed consent was 
 obtained from all participants . gait time and trunk acceleration ratio during stair climbing 
 were measured with a tri - axial accelerometer ( fit dot life , suwon , korea ) . trunk acceleration was calculated by obtaining the vector sums of 
 the anterior - posterior , medial - lateral , and vertical acceleration amplitudes . the trunk 
 acceleration ratio was then calculated by dividing the t2 trunk acceleration value by the l3 
 trunk acceleration value1 . we used three 
 3-step staircases ( rise=17  cm , tread=28  cm , width=50  cm ) placed directly in front of a 
 larger staircase4 . each participant was 
 asked to ascend the three stairs at their own pace , to use the dominant foot for the first 
 step , and to place only one foot on each step ( i.e. , to progress in a the differences in gait times and trunk acceleration were analyzed using independent 
 t - tests . the spss for windows statistical software package ( ver . 18.0 ; spss inc . , gait time and the trunk acceleration ratio when climbing stairs were significantly higher 
 in the old - old age group ( 4.1  0.8  s and 2.2  0.6 , respectively ) than in the older adults 
 group ( 3.5  0.4  s and 1.6  0.6 , respectively ; p<0.05 ) . gait time and trunk acceleration ratio during stair climbing in old - old adult females were 
 assessed in this study . our findings indicated that although there was no difference between 
 the groups in terms of lower extremity muscle strength , functional and trunk balance control 
 ability during stair climbing decreased in the old - old adult group compared to the older 
 adult group . oh - park et al . investigated the predictive utility , in terms of functional 
 decline , of stair negotiation times4 . they 
 reported that the 3-stair negotiation time was a meaningful measurement in a clinical 
 setting that allowed the risk of functional decline in older adults , including 
 high - functioning individuals , to be easily assessed . in addition , they determined the stair 
 negotiation time to be 0.5  s for significant deterioration and 0.2  s for significant 
 improvement . the trunk acceleration ratio serves as both an index of trunk oscillations and 
 a predictor of falling1 , 5 . trunk acceleration is defined as the rate of change of 
 trunk velocity , and a higher trunk acceleration ratio indicates that the velocity of the 
 upper trunk changes frequently during stair negotiation . our results also indicated that 
 old - old females had decreased upper trunk control , which minimized the motion of the head 
 and increased the probability of falling . therefore , we suggest that ascending stairs is one 
 of the biggest balance challenges in old - old adults and that gait time and the trunk 
 acceleration ratio are useful clinical markers for predicting falls in old - old 
 populations .
[ purpose ] this study investigated the effects of gait time and trunk acceleration ratio 
 in old - old adult females during stair climbing . [ subjects and methods ] twenty - five older 
 adult females who were able to walk independently volunteered for this study and were 
 categorized into two age groups ( older adults or old - old adults ) . 
 gait time and trunk 
 acceleration ratio were measured using an accelerometer during stair climbing . 
 [ results ] 
 gait time and trunk acceleration ratio when climbing stairs were significantly higher in 
 the old - old age group than in the older adults group . [ conclusions ] 
 these findings suggest 
 that old - old females have decreased upper trunk control . 
 in addition , gait time and the 
 trunk acceleration ratio during stair climbing are useful clinical markers for predicting 
 function and balance control ability in old - old elderly populations .