Journal of Geriatric Physical Therapy:
The Test-Retest Reliability of 10 Meters Maximal Walking Speed in Older People Living in a Residential Care Unit
Adell, Eva RPT1; Wehmhörner, Silke RPT2; Rydwik, Elisabeth RPT, PhD3,4
1Sollentuna Rehabilitation Unit for Older People, Sollentuna, Sweden
2Bromma Geriatric Clinic, Bromma, Sweden
3Research and Development Unit, Jakobsberg's Hospital, Stockholm City Council, Järfälla, Sweden
4Division of Physiotherapy, Department of Neurobiology, Caring Science and Society, Karolinska Institutet, Huddinge, Sweden
Address correspondence to: Elisabeth Rydwik, Research and Development Unit, Jakobsberg's Hospital, Stockholm City Council, Järfälla, Sweden ( email@example.com).
All authors declare no conflict of interest and no funding have been obtained for this study.
Background and Purpose:
It is very important to analyze and estimate physical limitations in older people to prevent falls and further physical decline. Walking speed can be used as an outcome measure for evaluating a physical exercise program, but to do so, relative and absolute reliability need to be established. No studies have evaluated the reliability of maximal walking speed in an aged population with different medical diagnoses. Therefore, the aim of this study was to investigate the reliability of walking speed through test retest in older people living in a residential care unit.
A sample of older people living in a residential care unit was invited to participate in the study. Maximal walking speed was measured for a distance of 10 m with an acceleration and deceleration phase of 2 m each. Data were collected twice for each individual within a 1-week interval.
Thirty-one subjects participated on both test occasions. The mean age was 89 years (74–100 years); 25 women and 6 men participated. The test-retest analysis showed an intraclass correlation coefficient (1,1) of 0.86 between the 2 tests. The mean value of the first occasion was 0.97 m/s (SD = 0.30 m/s), and the mean value of the second occasion was 0.95 m/s (SD = 0.29 m/s). The mean difference was −0.03 m/s (SD = 0.16 m/s), and the 95% limits of agreement for the mean difference were −0.33 to 0.27.
Discussion and Conclusion:
A maximum walking speed test in institution-dwelling older people aged 65 years and older, with several different diagnoses, shows high reliability. The method is easy to perform in a clinical setting at a minimal cost and can be recommended for use in this group before and after a training period. However, the variance of −0.33 to +0.27 m/s needs to be considered when evaluating the effect of a training period.
Walking is a fundamental part of everyday life and depends on balance, joint motion, endurance, and muscle strength.1 Several studies have shown that walking is the most common physical activity among older people,2,3 and it is practiced more regularly than more vigorous activities.4
Measuring walking speed is easy and can tell much about older adults living in a home care setting.5 Compared with other mobility tests such as chair stand, stair climbing, and Timed Up and Go, walking speed is the most frequently used method.6 Walking speed gives information about a person's physical performance. Also, the difference between habitual walking speed and maximal walking speed (fast walking) provides information about a person's functional reserve capacity.7 Both habitual and maximal walking speeds are influenced by age, sex, height, muscle strength in the lower extremities, and body composition.8,9 The difference between habitual and maximal walking speed can be explained by an increase in cadence, step length, and stride length in maximal walking speed compared to habitual speed.10 Walking speed can be useful as a measurement for screening older people who may need a detailed physical therapy evaluation and intervention.11,12 The method is easy to execute in a clinical setting, is inexpensive, and does not require any special equipment. It is also easy to administer.11,13 There are many different descriptions of how to perform the test. Different distances have been reported in the literature, primarily 4, 6, or 10 m, but longer distances have also been used. Differences in test distances make test comparisons difficult.1
Both habitual and maximal walking speeds are highly valid measurements in terms of both concurrent and discriminative validity.14 Walking speed can also predict fracture, cognitive decline, cardiovascular diseases, hospitalization, institutionalization, and mortality.6,15 A systematic review showed that several different cutoffs have been reported in the literature, but they vary depending on whether the target group is a healthy or frail population. The cutoff scores have been evaluated in relation to prediction of health-related outcomes, fear of falling, and fall risk. The most common value reported is 1 m/s.14 This cutoff has also been suggested in screening for sarcopenia in older people, and those who score below the cutoff should be transferred for body composition assessment.16 Habitual walking speed has been shown to be reliable in older people, but no studies have evaluated the reliability of maximal walking speed in older people with different medical diagnoses.14
Many older people living in various types of assisted living have several diagnoses and poor physical performance. These conditions may also result in the development of additional risk factors and a greater fall risk.17 It is very important to analyze and estimate physical limitations in these people to prevent falls and further physical decline. Exercise programs have been shown to reduce the risk of falling as well as physical decline.18,19 Walking speed can also be used as an outcome measure for evaluating a physical exercise program,20 but to do so, relative and absolute reliability need to be established. Therefore, the aim of this study was to investigate the reliability of maximal walking speed using test-retest in older people living in a residential care unit.
A sample of older people living in a residential care unit was invited to participate in the study. Both verbal and written information about the purpose of the study was given in accordance with the Helsinki declaration. Subjects who agreed to participate in the study gave written informed consent.
Inclusion criteria were people who could walk with or without walking aids and who could understand and follow given instructions. Exclusion criteria were people with infections or people who had recently had infections that affected their physical performance, people with psychiatric diagnoses such as depression, as well as stroke in the last 12 months and myocardial infarction in the last 6 months.
The number of and the most common diagnoses were retrieved from the patient's medical journals and listed. The subjects were also asked about their dependency in activities of daily living according to the Katz index.21
Data were collected twice for each individual with a 1-week interval. The subjects walked with or without walking aids. They performed one trial to get familiarized with the test and were then allowed a 5-minute rest before starting the test. After a week, the second test was performed under the same circumstances and at the same time of day. The subjects were not allowed to exercise between the test occasions beyond their normal exercise activities. The same comfortable footwear and walking aids were used on both occasions.
Maximal walking speed was measured for a distance of 10 m with an acceleration and deceleration phase of 2 m each. The subjects were instructed to walk to the first line and increase to maximum speed when crossing the first line until they crossed the second line. The evaluator walked beside the participant, began timing with a digital stopwatch when the subject's first foot crossed the starting line, and stopped the timing when the first foot crossed the second line.22,23
Intraclass correlation coefficient (ICC) (1,1),24 as well as Bland and Altman's 95% limits of agreement25,26 were analyzed using JMP 6.0 (SAS Institute, Cary, NC) and Excel 2007 (Microsoft, Redmond, WA). The 95% limits of agreement were introduced by Bland and Altman as an alternative and complement to the correlation coefficient for method comparison studies. Two methods may be highly correlated, yielding a high value for the correlation coefficient, although the agreement is low. The coefficient of the variation was calculated to express standard error as a percentage.27 “Line of equality” was used to obtain a visual estimate of the correlation between the two measurements.25 A paired t test was used to analyze whether there was a systematic difference between test occasions 1 and 2.
Of the 35 participants who were enrolled in the study, 4 dropped out at the first test occasion due to fatigue, so 31 subjects participated on both test occasions. The mean age was 89 years (74–100 years); 25 women and 6 men participated and 24 subjects used a walker. Fifteen subjects were dependent in personal activities of daily living, whereas 11 were dependent in daily bath or shower (Table 1). The most common diagnoses were cardiovascular diseases, joint diseases, impaired vision and/or hearing, and osteoporosis (Table 2).
The results of the test at occasions 1 and 2 are shown in Figure 1. The analysis showed an ICC (1,1) of 0.86 between the 2 tests. The mean value of the first occasion was 0.97 m/s (SD = 0.30 m/s), and the mean value of the second occasion was 0.95 m/s (SD = 0.29 m/s). The mean difference was −0.03 m/s (SD = 0.16 m/s), and the Bland and Altman's 95% limits of agreement for the mean difference were −0.33 to + 0.27 m/s (Figure 2). Calculation with the paired t test showed that there was no systematic difference between measurements (P = .3742). The coefficient of variation was 11.4%.
The result of the study showed a high correlation between tests with a mean difference of 0.03 m/s. To our knowledge, no studies have evaluated test-retest reliability for maximal walking speed in this target group. According to previous studies, ICC values for similar target groups vary between 0.79 and 0.94 for habitual walking speed.28,29 One study has evaluated the reliability of maximal walking speed on a GaitRite showing an ICC of 0.97; the tests were, however, performed during the same day.30 Taken together, the difference in measurement, distance, and speed limits comparability.
ICC is a relative measure of variation within subject in relation to the variation between subjects and takes into account the systematic error and is the recommended choice in these types of analyses.24 Absolute reliability has been suggested to be measured with standard error of measurement31 or Bland and Altman's “95% limits of agreement25,32 because it shows the difference between the 2 measurements. The advantage with Bland and Altman's method is that it also calculates the standard deviation of the difference between measurements. In this study, the Bland and Altman's analyses showed variance of −0.33 to +0.27 m/s. This may seem elevated, but the frail subjects' day-to-day variability must be considered. In addition, the performance of maximal walking speed has been shown to be related to several factors such as age, gender, leg extensor power, standing balance, and physical activity.33
Another explanation of the difference between the 2 measurements could be due to the instructions from the test leader. When the test leader encouraged the subject to walk as fast as possible an initial reduction of walking speed was in some cases observed, but maximum speed was soon reached. This effect should be considered when performing the test. Also, the subjects included in this study were frail with several diagnoses and many of them were dependent on personal activities of daily living. This might influence each subject's daily condition and thus also the differences between the 2 test occasions. Similar findings have been reported in a study evaluating the reliability of Timed Up and Go. The study showed that the slower the subjects performed the test, the more the variance increased.34 Another explanation of the difference between tests 1 and 2 could be the instructor's tone of voice, body language, and feedback.
In health care and rehabilitation settings, knowledge of an older person's physical performance is of utmost importance to deliver appropriate care. The emphasis on individual targeted exercise programs for frail older people19 requires valid and reliable instruments. The variance of −0.33/+0.27 m/s needs therefore to be taken into account if the test is used to evaluate, for example, a physical exercise program. A change within the limits cannot be regarded as a true change. This is of importance both in a clinical setting as well as in randomized controlled trials. Another clinical implication is that walking speed has been suggested to be used as a functional “vital sign” to determine outcomes such as functional capacity, discharge location, and the need for rehabilitation.35
The major limitation of the study is the rather small sample size in relation to the analyses of 95% limits of agreement. According to Altman,36 the sample size should be large enough to allow the limits of agreement to be estimated well; otherwise, there might be a risk of too much variance in ranges. Thus a sample size of at least 50 but preferably larger is desirable.36 This might also explain the results of this study.
Maximum walking speed tests in institution-dwelling people aged 74 years and older, with several different diagnoses, shows high reliability. The method is easy to perform in a clinical setting at a minimal cost. The method can be recommended for use in this group before and after a training period. However, the mean difference −0.03 m/s and Bland and Altman's 95% limits of agreement of −0.33 to +0.27 m/s needs to be taken into account when evaluating the effect of a training period.
1. Graham E, Ostir GV, Fisher SR, Ottenbacher KJ. Assessing walking speed in clinical research: a systematic review. J Eval Clin Pract. 2008; 14:(4):552–562.
2. Frandin K, Grimby G, Mellstrom D, Svanborg A. Walking habits and health-related factors in a 70-year-old population. Gerontology. 1991; 37:(5):281–8.
3. Lee YS. Gender differences in physical activity and walking among older adults. J Women Aging. 2005; 17(1/2):55–70.
4. Lamb SE, Bartlett HP, Ashley A, Bird W. Can lay-led walking programmes increase physical activity in middle-aged adults? A randomised controlled trial. J Epidemiol Community Health. 2002; 56:(4):246–252.
5. Bohannon RW. Measurement of gait speed of older adults is feasible and informative in a home-care setting. J Geriatr Phys Ther. 2009; 32:(2):22–23.
6. Cooper R, Kuh D, Cooper C, Gale CR, Lawlor DA, Matthews F. Objective measures of physical capability and subsequent health: a systematic review. Age Ageing. 2011; 40:(1):14–23.
7. Bridenbaugh SA, Kressig RW. Laboratory review: the role of gait analysis in seniors' mobility and fall prevention. Gerontology. 2010; 57:(3):256–264.
8. Bohannon RW. Comfortable and maximum walking speed of adults aged 20–79 years: reference values and determinants. Age Ageing. 1997; 26:(1):5–19.
9. Bohannon RW. Population representative gait speed and its determinants. J Geriatr Phys Ther. 2008; 31:(2):49–52.
10. Chui KK, Lusardi M. Spatial and temporal parameters of self-selected and fast walking speed in healthy community-living adults aged 72–98 years. J Geriatr Phys Ther. 2010; 33:(4):173–183.
11. Cesari M, Kritchevsky SB, Penninx BW, et al. Prognostic value of usual gait speed in well-functioning older people: result from the health, aging and body composition study. J Am Geriatr Soc. 2005; 53:(10):1675–1680.
12. Harada N, Chiu V, Damron-Rodriguez JA, Fowler E, Siu A, Reuben DB. Screening for balance and mobility impairment in elderly individuals living in residential care facilities. Phys Ther. 1995; 75:(6):462–469.
13. Guralnik JM, Ferrucci L, Pieper CF, et al. Lower extremity function and subsequent disability: consistency across studies, predictive models and value of gait speed alone compared with the short physical performance battery. J Gerontol A Biol Sci Med Sci. 2000; 55:(4):M221–M231.
14. Rydwik E, Bergland A, Forsén L, Frändin K. Investigation into the reliability and validity of the measurement of elderly people's clinical walking speed: a systematic review. Physiother Theory Pract. 2012; 28:(3):238–56.
15. Cooper R, Kuh D, Hardy R. Mortality Review Group, FALCon and HALCyon Study Teams. Objectively measured physical capability levels and mortality: systematic review and meta-analysis. BMJ. 2010; 341:c4467
16. Fielding RA, Vellas B, William JE, et al. Sarcopenia: an undiagnosed condition in older adults. Current consensus definition: prevalence, etiology, and consequences. International working group on sarcopenia. J Am Med Dir Assoc. 2011; 12:(4):249–256.
17. Inouye SK, Studenski S, Tinetti ME, Kuchel GA. Geriatric syndromes: clinical, research, and policy implications of a core geriatric concept. J Am Geriatr Soc. 2007; 55:(5):780–791.
18. Sherrington C, Whitney JC, Lord SR, Herbert RD, Cumming RG, Close JC. Effective exercise for the prevention of falls: a systematic review and meta-analysis. J Am Geriatr Soc. 2008; 56:(12):2234–2243.
19. Forster A, Lambley R, Young JB. Is physical rehabilitation for older people in long-term care effective? Findings from a systematic review. Age Ageing. 2010; 39:(2):169–175.
20. Lopopolo RB, Greco M, Sullivan D, Craik RL, Mangione KK. Effect of therapeutic exercise on gait speed in community-dwelling elderly people: a meta-analysis. Phys Ther. 2006; 86:(4):520–540.
21. Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged: the index of ADL: a standardized measure of biological and psychosocial function. J Am Med Assoc. 1963; 185:914–919.
22. Finch E, Brooks D, Stratford PW, Mayo NE. Physical Rehabilitation Outcome Measures. A Guide to Enhanced Clinical Decision Making. 2nd ed. Hamilton, Canada: B. C. Decker; 2002; :152–155.
23. Salbach NM, Mayo NE, Higgins J, Ahmed S, Finch LE, Richards CL. Responsiveness and predictability of gait speed and other disability measures in acute stroke. Arch Phys Med Rehabil. 2001; 82:(9):1204–1212.
24. Rankin G, Stokes M. Reliability of assessment tools in rehabilitation: an illustration of appropriate statistical analyses. Clin Rehabil. 1998; 12:(3):187–199.
25. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986; 1:307–310.
26. Bland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res. 1999; 8:(2):135–160.
27. Bruton A, Conway JH, Holgate ST. Reliability: what is it, and how is it measured? Physiotherapy. 2000; 8:(2):94–99.
28. Jette AM, Jette DU, Ng J, Plotkin DJ, Bach MA. Are performance-based measures sufficiently reliable for use in multicenter trials? Musculoskeletal Impairment (MSI) Study Group. J Gerontol A Biol Sci Med Sci. 1999; 54:(1):M3–M6.
29. Rolland YM, Cesari M, Miller ME, Penninx BW, Atkinson HH, Pahor M. Reliability of the 400-m usual-pace walk test as an assessment of mobility limitation in older adults. J Am Geriatr Soc. 2004; 52:(6):972–976.
30. Lusardi M, Pellecchia GL, Schulman M. Functional performance in community living older adults. J Geriatr Phys Ther. 2003; 26:(3):14–22.
31. Haley SM, Fragala-Pinkham MA. Interpreting scores of tests and measures used in physical therapy. Phys Ther. 2006; 86:(5):735–743.
32. Moe-Nilssen R. A method for reliability analysis of speed-related repeated measures gait data. Gait Posture. 2011; 33:(2):297–299.
33. Sallinen J, Mänty M, Leinonen R, Kallinen M, Törmäkangas T, Heikkinen E, Rantanen T. Factors associated with maximal walking speed among older community-living adults. Aging Clin Exp Res. 2011; 23:(4):273–278.
34. Nordin E, Rosendahl E, Lundin-Olsson L. Timed “Up & Go” test: reliability in older people dependent in activities of daily living - Focus on cognitive state. Phys Ther. 2006; 86:(5):646–655
35. Fritz S, Lusardi M. White paper: “walking speed: the sixth vital sign.”. J Geriatr Phys Ther. 2009; 32:(2):46–49.
36. Altman DG. Practical Statistics for Medical Research: Some Common Problems in Medical Research. 1st ed. London: Chapman & Hall; 1991; :396–403.
evaluation; physical function; physical performance; test-retest; screening
© 2013 The Section on Geriatrics of the American Physical Therapy Association.