Procedural Differences Directly Affect Timed Up and Go Times (2009)

To the Editor: The Timed Up and Go (TUG) is a simple timed test of basic mobility skills involving rising from a chair, walking a distance of 3 m, turning, walking back to the chair, and sitting down again.1 It is currently the most widely used test in clinical guidance on falls prevention in older people and has been extensively employed in the examination of elderly people,2 but despite the fact that the test is seen as an effective method of assessing basic mobility performance, the clinical value of the association between TUG outcomes and falls remains under debate. One major limitation in trying to establish a universal measure is that procedural differences often exist in instructions given to subjects and in the layout of the test.2 The aim of this study was to determine whether different verbal instructions and marker layouts have an effect on TUG times. Fourteen healthy young adults (mean age 21, range 19–25) and 14 healthy elderly adults (mean age 67, range 60–76) voluntarily participated in this study. TUG measurements were obtained using an ordinary armchair with a seat height of 47 cm.3 A rectangular mark on the floor (8 × 2.5 cm) was used as a turning point, because it has been reported that many people found it confusing as to where they were supposed to turn when a line was used.4 The following instructions were used: “Please get up on the word go, stand upright, walk to the marker on the floor, turn around, return to the chair, and sit down.” “Please get up on the word go, stand upright and walk as quickly and as safely as possible to the marker on the floor, turn around, return to the chair, and sit down.” “Please get up on the word go, stand upright and walk the fastest you possibly can to the marker on the floor, turn around, return to the chair, and sit down.” All three instructions were given with a rectangle marker as the turning point. An additional condition (B2) was added, in which instruction B1 was also given using a cone (40 × 40 cm, 52 cm high) to mark the turning point. Subjects were asked to perform the TUG test while wearing seven inertia measurement units (IMUs, MTx, Xsens Technologies B. V., Enschede, the Netherlands), which measured the three-dimensional orientation of the lower extremities and the back. A seven-link sagittal model was created using a methodology described elsewhere.5 Sensor information combined with the model allowed for rater independent analysis of the TUG. The test started when the torso was flexed more then 5° and ended when normal sitting height was reached, with the torso tilted to within 5° of the original sitting position. Differences in total TUG times (P<.05) between age groups were detected in the conditions in which specific instructions were given regarding the walking speed, whereas no such difference was found when the pace of walking was not specified (Figure 1). Times differed (P<.01) between all conditions within the elderly group. A similar pattern was seen for the young group, although no difference (P=.31) in time was found between the two marker conditions (B1 and B2). Mean Timed Up and Go (TUG) times and standard deviations of the young adult group (white bars) and elderly group (dark bars). (A) Self-selected walking speed, with a rectangular mark as marker; (B1) “As quickly and as safely as possible,” with a rectangular mark as marker; (B2) “As quickly and as safely as possibly,” with a cone as marker; (C) “The fastest you possibly can,” with a rectangular mark as marker. All conditions and age groups were compared. A repeated-measure analysis of variance was used (F ratio of 72.1) with the TUG times as dependent variables, the four conditions as within-subject variables, and the two age groups as between-subject variables. Bonferroni adjustments were applied for post hoc comparison between groups and conditions (α=0.05).Asterisks indicate a significant P-value lower than .05 but above .001. Thus, verbal instructions and marker layouts affect TUG outcomes in healthy elderly people. In the younger subjects, the instructions, but not the markers (bar or cone), affected TUG times. The greatest mean difference between age groups was found for the condition that used a cone as a marker while instructing subjects to go as quickly and as safely as possible (B2). Variability, between instructions and within the test group, was less when a definite statement about speed was given. These results show that comparisons between TUG times of several studies are unreliable if procedural differences are not taken into account. Therefore, clinicians need to be aware that the instructions given and the tools used, marker and chair type,3 can alter the outcome of the test. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this letter. This research was funded through a joint Medical Research Council–King's College London Studentship, and the manuscript is without bias in the presentation of results. Author Contributions: JB conceived the study; participated in study design, data collection, calculation, and statistical analysis; and drafted and revised the letter. CA participated in study design and data collection. IS conceived the study, participated in study design and statistical analysis, revised the letter, and gave final approval of the version to be published. All authors read and approved the final letter. Sponsor's Role: The funding agencies played no role in the design, conduct, data management, analysis, or letter preparation.