Bramell-Risberg et al The proportion of low achievers (,10 seconds) among cases was, for right/left leg, 50%/51%, compared with 28%/26% among the controls (P , 0.001). The corre- sponding proportions for high achievers ($30 seconds), for right/left leg, were 28%/27% and 53%/53%, respectively (P , 0.001). Discussion In this cross-sectional, population-based study, we found a significant association between cognitive impairment and measures of physical performance targeting the lower extremities, speed of movement, coordination, and postural control. In the adjusted model, the results of physical per- formance tests performed at high speed and the OLS test were significantly associated with cognitive impairment. The results of this study showed that separate, objective, perfor- mance-based measures related to lower extremity function and postural control, which emphasize speed and challenge physical capacity, are useful in investigating the relationships between physical and cognitive function. This is in agree- ment with studies made by such authors as Tabbarah et al,4 Wang et al,43 Aggarwal et al,1 Fitzpatrick et al,3 Eggermont et al,10 and Bottiggi and Harrison.44 However, comparisons with the results of previous research may be difficult, due to differences in study design and test methodology. We found that slower speed in the fast-walking condi- tion was associated with cognitive impairment, in agreement with previous studies.3–5,45 Poor performance in fast WS was found to be more predictive of significant cognitive decline over a 3-year follow-up than performance in self-selected WS.5 Tabbarah et al4 reported that fast WS was related to baseline cognition, and that subjects with poorer baseline cognition were more likely to experience a decline in fast WS. Fitzpatrick et al3 found that the risk of low cognition was almost twice as great in slow walkers than in fast walkers when measuring fast WS. Others have found self-selected WS to be associated with cognitive impairment.6,46–48 In our study we found no such association, which may be due to our study design. The subjects were provided with several meters to accelerate and decelerate before and after the test, as well as a long walking distance, which are methods that have been recommended to achieve a steady state of walking in the frail elderly.49 In our study, a longer time to perform the walking 2 × 15 m test was related to increased risk of being cognitively impaired, but only at the higher walking speed. The ability to turn is related to cognitive impairment,4 and it was included in this test. The requirements of high speed during walking, the long distance, and the 180° turn may have 202 submit your manuscript | www.dovepress.com Dovepress Dovepress challenged level of fitness, endurance, and postural control. Correlations have been found between the results of this test and several balance measures.32 Walking has generally been viewed as a largely automated motor task that requires minimal higher-level cognitive input. This view may be too simplistic and, in fact, walking may be a complex motor task that demands attention and is related to higher cognitive functions, such as executive function.50–53 Gait parameters have been found to be associated with a decline in specific cognitive domains.45,47,50 Hausdorff el al50 found higher self-selected walking speed to be associated with good performance in executive function, but not with memory or cognitive function in general in community- dwelling subjects. In their prospective study, Verghese et al47 found that declines in memory and executive function were associated with gait velocity. Soumaré et al45 found a slower fast WS at baseline, as well as the degree of decline in fast WS, to be associated with poorer performance in cognitive tests of verbal fluency and psychomotor speed. The TUG test is a test of basic functional mobility, and its performance has been found to be correlated with balance, gait speed, and functionality.29,54 The standard procedure adopted in the test is to walk at a self-selected speed; how- ever, in our study, the subjects were also asked to walk as fast as possible without running. TUG test performance at self-selected speed was found to be significantly different between controls and subjects with AD, but not between controls and subjects with mild cognitive impairment.10 We found TUG time to be associated with cognitive impairment at the higher speed, but not at the self-selected walking speed, which is in agreement with the findings of others who urged their subjects to perform the test at a higher speed.55 A longer time on the TUG test, performed at fast speed, has also been associated with lower executive function.53 The chair stand test has been regarded as an indicator of lower limb strength in older people; however, performance is also influenced by other physiological and psychological factors related to balance and mobility.36 The test procedure used may vary in the following factors: starting the timing; whether the timing ceases after completing the fifth stand or upon returning to a seated position after the last stand; whether support of the arms is allowed; and whether speed of performing the task is stipulated or not.56 We used the proce- dure proposed by Bohannon,56 timing five completed stands, with the emphasis on fast performance and performing the test without support of the upper limbs. We found this test to be associated with cognitive impairment, in agreement with earlier studies,4,48 while others have not.43,57 Clinical Interventions in Aging 2012:7