Proceedings of The Physiological Society
King's College London (2009) Proc Physiol Soc 14, C18
Quantitative component analysis of the Timed Up and Go (TUG) test performed by young and older adults
J. Bergmann1, C. Alexiou1, C. Smith1
1. Applied biomedical research, King's College London, London, United Kingdom.
Falls are common in old age and frequently cause severe injury. Although not all falls result in major injury, 20% of them still require medical attention (1). It is crucial to determine which older people are at high risk of falling in order to prevent injury and initiate appropriate interventions. One of the most widely used clinical test to determine fall risk is the Timed Up and Go (TUG) test. The TUG is a quick, simple and effective test of basic mobility skills, and consists of a person standing up from a seated position, walking 3 meters, turning 180° and walking back to sit down in the chair under timed conditions (2). The different components i.e. standing up, walking, turning and sitting down, that occur during the TUG have recently been quantified using gyroscopes and accelerometers (3). We used a similar method to objectively time each functional component independently and determine how much every component contributed to the total outcome in a group of healthy young (n=11; mean age=20 years; range=19-21 years), and old (n=11; mean age=68 years; range=60-76 years) people. Data was normally distributed as found by the Kolmogorov-Smirnov test and Q-Q plots. An Independent Samples T-Test was used to determine differences between the two groups. Pearson correlation coefficients (r) were calculated for each component to establish how well they related to the total TUG time. Total TUG time and the component times of standing up, turning and walking back, differed significantly (p<0.05) between age groups. No difference was found between young and old subjects during walking of the first 3 meters (p=0.81) and sitting down (p=0.18). The greatest differences between groups were found for the total TUG time (p=0.001) and turning time (p=0.007). All components correlated well to the total TUG time (range; r= 0.344-0.727) in the young people, except for the standing up component that showed no correlation (p=0.50) with the total TUG time. In the group of older people all components correlated (range; r=0.266-0.719) with the total TUG time. However, the standing up component still had the lowest correlation. These results show that although the total TUG time differs between young and old people, not all components allow for a clear distinction between the two age groups. This suggests that certain tasks (e.g. turning) are better in distinguishing between age groups then others (e.g. walking of the first three meters). Furthermore, although some components correlated well with the total TUG time, other components, especially the standing up component, related poorly or not at all to the total TUG time. Thus, proving that additional information about basic mobility skills can be obtained by performing a quantitative component analysis of the TUG test.
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