Volume 89, Issue 9 , Pages 1686-1692, September 2008
Use of the Six-Minute Walk Test Poststroke: Is There a Practice Effect?
Article Outline
Abstract
Liu J, Drutz C, Kumar R, McVicar L, Weinberger R, Brooks D, Salbach NM. Use of the six-minute walk test poststroke: is there a practice effect?
Objectives
To determine whether a practice effect occurs across 2 trials of the six-minute walk test (6MWT) among community-dwelling people within 1 year poststroke and to identify characteristics distinguishing people who show a practice effect from those who do not.
Design
Secondary analysis of scores on 2 trials of the 6MWT administered approximately 30 minutes apart at baseline in a randomized controlled trial.
Setting
General community.
Participants
People (N=91) living in the community with a residual walking deficit within the first year of a first or recurrent stroke.
Interventions
Not applicable.
Main Outcome Measure
Distance walked on the 6MWT.
Results
Mean 6MWT scores ± SD for trials 1 and 2 were 196±119m and 197±126m, respectively (n=83). The mean difference in 6MWT performance across trials was 0±35m (95% confidence interval [CI], –7 to 8m). The Pearson correlation coefficient between 6MWT distances was .96 (P<.001), and the intraclass correlation coefficient was .98 (95% CI, .97–.99). The Bland-Altman plot showed no clear pattern. Participants whose improvement was equal to or greater than the minimal detectable change of 29m between trials (14%) did not significantly differ from those in the rest of the study sample; however, they tended to be younger (P=.05) and more likely to have a mild or moderate gait deficit (P=.06).
Conclusions
Findings do not support a practice effect across 2 trials of the 6MWT in individuals within 1 year poststroke. Thus, a practice walk does not appear necessary. Further research is recommended to evaluate the influence of young age, acute stroke, and mild-to-moderate gait deficit on practice effects.
Key Words: Rehabilitation, Stroke, Walking
List of Abbreviations: ADLs, activities of daily living, BBS, Berg Balance Scale, CI, confidence interval, COPD, chronic obstructive pulmonary disease, ICC, intraclass correlation coefficient, MDC, minimal detectable change, 6MWT, six-minute walk test, 12MWT, twelve-minute walk test, 2MWT, two-minute walk test, V̇o2max, maximal oxygen uptake
MORE THAN 50,000 CANADIANS sustain a stroke each year.1 Although 85% of people with stroke are able to walk independently at 6 months, only 25% regain normative ambulation.2 Moreover, a systematic review of the literature on stroke prognosis reported that little functional recovery occurs more than 6 months after a stroke has occurred.3 Ninety-three percent of people with stroke consider independent community ambulation to be important or essential.4 Although many aspects of walking ability, such as speed and independence, are affected by stroke, walking distance is an important indicator of the ability to walk in the community. Functional walk distances measured using the 6MWT and the 12MWT5 in people with stroke have been reported to be approximately 42% to 50% of those of healthy older adults.6, 7, 8 Studies of functional walk tests in people with stroke have found mean 6-minute walk distances ranging from 209 to 300m,9, 10, 11, 12 which is below the 267- to 332-m distance required for instrumental ADLs such as grocery shopping, going to drugstores, or attending medical appointments.13, 14 Such distances have been determined in previous research by measuring the distance required to walk from the closest or designated disabled parking space through a portion of the chosen site in a number of locations.14 Initial stroke rehabilitation, therefore, is largely focused on walking, with the goal of increasing functional exercise capacity and independence.
The 6MWT is a commonly used standardized measure of exercise tolerance and functional walking capacity in people with compromised mobility.5, 10, 15, 16 Although the 2MWT and 12MWT can be used to evaluate functional walking ability, the 6MWT is often preferred over these other tests for several reasons. Although the 2MWT is a useful measure of sensorimotor parameters, such as gait and symmetry, the 6MWT better demonstrates exercise capacity and is more reflective of the requirements of ADLs.5, 16 In addition, the 2MWT is less reliable and responsive than the 6MWT.16 In contrast, the 12MWT may be unnecessarily time-consuming to administer and unduly taxing for elderly and clinical populations, because studies have found that walking speed tends to plateau at approximately 3 to 4 minutes.5 Although timed walk tests conducted over short distances such as 10m provide a quick and easy measure of walking speed poststroke,17 speeds computed using this distance have been observed to overestimate 6MWT performance and should complement but not replace measures of functional walking capacity.18
The 6MWT was initially designed to evaluate functional capacity, endurance, and exercise tolerance among people with cardiorespiratory and cardiovascular conditions.19, 20 In these populations, 6-minute walk distance has been shown to correlate with V̇o2max and maximum work capacity.19, 21, 22, 23, 24, 25 However, in studies examining the relationship between 6-minute walk distance and V̇o2max in people with stroke, distance walked showed either moderate26 or no27 significant correlation. Other stroke-specific impairments such as diminished motor control may influence walking function to a greater extent than cardiovascular fitness in people with stroke.26, 27 The 6MWT has been shown to be sensitive to change as a result of rehabilitation interventions targeting walking performance.9, 28, 29, 30 Furthermore, improvement in 6-minute walk distance has been observed to concur with improvement in comfortable and maximum walking speed.9
Several studies have examined the possibility of a practice effect over repeated trials of the 6MWT; however, there is inconclusive evidence about how many trials should be recommended in clinical practice. Specifically, it has been shown that 6-minute walk distance increases with repeated trials among healthy adults,16, 31, 32 people with COPD, and people with cardiac impairments.19, 33, 34, 35, 36, 37, 38 Potential reasons for this apparent practice effect include improvement in coordination, discovery of optimal stride length, and decrease in anxiety.15 Reported estimates of the magnitude of the practice effect on 6-minute walk distance range from 4.5% to 33% of the initial test distance.6, 20, 33, 36, 39 Investigating the occurrence of a practice effect is critical because it relates to the accuracy of measuring a person's walking capacity. When a practice effect occurs, performance on the first trial underestimates the true level of ability and represents a biased measure of the extent of functional walking deficit.
In people with stroke, there is also the possibility that participants may experience deterioration in 6-minute walk distance over repeated trials because of fatigue. Increased levels of fatigue poststroke are well documented in the literature.39, 40, 41 Poststroke fatigue has been found to be associated with impairment in functional ability.39 Therefore, particularly in those individuals with considerable functional impairment who rarely walk for 6 minutes continuously, a single performance of the 6MWT could potentially cause enough fatigue to affect the distances obtained during subsequent trials. As with a practice effect, it is important that clinicians be aware of any fatigue effect over multiple trials of the 6MWT, because the presence of such a phenomenon would lead to an underestimation of the treatment effect being assessed.
The presence of a practice effect in the 6MWT has been evaluated using various statistical approaches, including a comparison of means,20, 31, 32, 33, 34, 37 a Pearson correlation between 6MWT scores,31, 33 test-retest reliability of 6-minute walk distances using the ICC,34, 37, 38, 42 and a Bland-Altman plot.34 In many of these studies, a combination of statistical methods was used without defining what findings would be considered evidence of a practice effect. Use of the Pearson correlation has been criticized because it does not capture agreement but the degree to which scores on repeated trials relate in a linear manner.43 Perfect agreement between pairs of scores is reflected, however, by a correlation value of 1.43
Eng et al27 have reported the SE of measurement44 for the 6MWT among community-dwelling people with stroke. The SE of measurement can reflect the level of precision in estimating change using a particular measure.44 Using the SE of measurement, an MDC reflecting the level of measurement error in a change score can be calculated.45 An improvement greater than error (ie, the MDC) could be considered a practice effect.
To our knowledge, the need for a familiarization test when administering the 6MWT in the stroke population has not been examined. Thus, the objective of the present study was to evaluate whether a practice effect exists with repeated trials of the 6MWT in people in their first year poststroke. The secondary objective was to determine which characteristics distinguish people who show a practice effect beyond the level of measurement error from those who do not.
Methods
Overview of Research Design
Data were obtained from a randomized controlled trial conducted to evaluate the effect of task-oriented training on walking capacity9 among 91 community-dwelling subjects within 1 year poststroke. The 6MWT was the primary measure of walking and was part of a battery of performance-based and self-report measures described elsewhere.9, 46, 47 At each evaluation, a trained research evaluator administered the 6MWT twice, approximately 30 minutes apart. Balance was evaluated using the BBS.48 Data collected at baseline were analyzed in the current study. Ethics approval and informed consent were obtained at the time of the original study.
Participants
Participants were recruited from 9 hospitals and 2 rehabilitation centers in Montreal and Quebec City, QC. Inclusion criteria for the 91 participants were a clinical diagnosis of a first or recurrent stroke; an interval of 1 year or less between the most recent stroke and time of recruitment; discharge from physical rehabilitation; the presence of a residual walking deficit; ability to walk 10m independently using an aid or orthotic, with or without supervision; mental competency as verified using the telephone version of the Mini-Mental Status Examination49; ability to comprehend the instructions for the testing procedures; and residence in the community.
People were excluded if their neurologic deficit was caused by metastatic disease, they had recovery of walking ability comparable to age-specific and sex-specific norms6 for the 6MWT, place of residence was in a permanent care facility, or presence of comorbidity precluded participation in the study interventions.
Measurement
Walking capacity was measured using the 6MWT.5 Using a standardized protocol developed to obtain reference values for the 6MWT among healthy adults,6 participants were instructed to walk back and forth along a 20-m corridor and to cover the maximum distance possible in 6 minutes, taking rests as needed. The maximum distance covered was recorded. Evaluators provided standardized encouragement every 30 seconds, which is consistent with current recommendations.15, 50, 51 Participants were told “you're doing well, keep up the good work.” Two trials were performed at baseline approximately 30 minutes apart. During the test interval, participants were seated and performed tests of upper-extremity function or completed questionnaires. If an assistive device was used, the type of device was recorded.
To address the secondary objective, scores on the BBS,48 baseline walking speed deficit, and the use of assistive devices were analyzed. The BBS is a 14-item measure designed to evaluate balance in older adults. For each of the 14 tasks, participants are scored on a 5-point scale based on their ability to maintain their balance while performing the task. Total scores can vary from 0 to 56, with ranges of scores corresponding to low (41–56), medium (21–40), and high (0–20) fall risk.52, 53, 54 Three levels of gait deficit were defined using walking speed derived from performance on a 5-m walk test.9 The cutoff points used to determine mild (≥0.7m/s), moderate (0.3 to <0.7m/s), and severe (<0.3m/s) gait deficit were identified based on natural frequency groupings observed in previous research.17
Data on sociodemographics (age, sex, education level, number of comorbid conditions) and stroke characteristics (side and type of stroke, number of strokes, side of hemiplegia, days poststroke) were originally obtained from the medical charts.
Data Analysis
Baseline participant characteristics and scores on study measures were summarized using means, SDs, and percentages, as appropriate. A practice effect was operationally defined using the 4 following methods. The first was a statistically significant improvement in the mean distance walked between 2 trials of the 6MWT, evaluated using a paired t test and expressed with the 95% CI. The second was a Pearson correlation of less than .75 between 6-minute walk distance in successive trials. When the r value equals 1, there is perfect agreement between trial 1 and trial 2 scores, and the Pearson correlation and the ICC concur in value.43 The third was an ICC of less than .75 for 6-minute walk distance in 2 successive trials. An ICC of greater than .75 is considered to be indicative of good test-retest reliability; therefore, ICCs below this level would suggest that trial 1 (the test) differed from trial 2 (the retest).55 The fourth was a Bland-Altman plot56 of the means and the differences in 6-minute walk distance for each subject, demonstrating a P value for the Spearman rank correlation coefficient of less than .05, indicating that the magnitude of the difference in scores varies by level of walking capacity.
Because previous studies have not operationally defined practice effect and no single method of evaluation has been identified as superior to the others, the present study considers a practice effect to be present only if all 4 criteria have been satisfied. It was hypothesized that a practice effect similar to that reported in other populations would be associated with repeated performances of the 6MWT.
To address the secondary objective, the difference in 6-minute walk distance between the 2 trials was classified as being beyond or less than an MDC90 of 29m. The MDC90 is interpreted as the interval beyond which 90% of true values will be found45; therefore, any value greater than the specified MDC is unlikely to be a result of chance and can be considered representative of a true change beyond the level of measurement error. An MDC of 29m was derived using the SE of measurement for the 6MWT of 12.4m from a study of people with stroke with characteristics similar to those of the present study.27 Although the magnitude of the MDC may vary across different levels of walking deficit,57 it is preferable to considering any difference in 6-minute walk distance beyond 0m as an indication of change. Participants in the present study were categorized into 1 of 3 subgroups according to their change in 6-minute walk distance (≤–29m, –28m to 28m, ≥29m), representing the proportion of participants who deteriorated, remained unchanged, and improved.
Cross-tabulations were then generated to determine whether age, comorbidity, number of strokes, number of months since stroke, severity of gait deficit, use of gait aid, or fall risk distinguished the participants whose 6-minute walk distance improved by greater than the MDC from those who did not.43 Because the expected frequency of several cells in these tables was less than 5, a Fisher exact test was used. This test evaluates whether the probability of obtaining the observed correlations between the 6MWT performances and participant characteristics in each stratum is statistically significant. For all statistical analyses, a type I error level of .05 determined statistical significance. Analyses were carried out using SPSS software.a
Results
Although 91 participants were enrolled in the study, 8 were eliminated from the dataset because these participants were missing 6MWT data. Three of these 8 participants did not perform either 6MWT because they failed a medical screen for this test. The remaining 5 were evaluated at an alternate test site, where a second trial was not administered.
Analyses were conducted on the remaining sample of 83 participants. The characteristics of the study participants are summarized in table 1. Among the 83 participants, 52 (63%) were men, and 31 (37%) were women. Age ranged from 38 to 91 years (mean ± SD, 72±10y), and the mean number of days poststroke was 227±78d. Nearly half of the participants were classified as having moderate gait deficits (42%), followed by 38% and 21% in the mild and severe categories, respectively. BBS scores ranged from 5 to 56, with a mean score of 41±12 overall.
Table 1. Characteristics of the Study Participants (n=83)
| Characteristic | Values |
|---|---|
| Age (y) | 72±10 (38–91) |
| Sex | |
| Male | 52(63) |
| Female | 31(37) |
| Education level | |
| None–primary | 23(28) |
| Secondary | 32(39) |
| College/university | 28(34) |
| Walking aid used | |
| None | 37(45) |
| Cane | 38(46) |
| Walker | 8(10) |
| Side of hemiplegia | |
| Left | 37(45) |
| Right | 45(54) |
| Bilateral | 1(1) |
| Side of stroke | |
| Left | 42(51) |
| Right | 37(45) |
| Bilateral | 3(4) |
| Missing | 1(1) |
| Type of stroke | |
| Ischemic | 69(83) |
| Hemorrhagic | 14(17) |
| No. of strokes | |
| 1 | 72(87) |
| 2 | 10(12) |
| >2 | 1(1) |
| Days poststroke | 227±78(57–374) |
| No. of comorbid conditions | |
| 0–1 | 23(28) |
| 2–3 | 32(39) |
| 4–9 | 28(34) |
| Severity of gait deficit | |
| Mild | 31(38) |
| Moderate | 35(42) |
| Severe | 17(21) |
| BBS score (0−56) | 41±12(5–56) |
Determination of Practice Effect of the 6MWT
The mean 6-minute walk distance for trial 1 and trial 2 was 196±119m and 197±126m, respectively. There was no statistically significant improvement in mean 6-minute walk distance (mean difference, 0±35m; 95% CI, –7 to 8) between trial 1 and trial 2.
The correlation between 6-minute walk distances at trial 1 and 2 was .96 (P<.001). The R2 value of .92 indicates that the trial 1 performance explained 92% of the variability in trial 2 performances (fig 1).
Fig 1.
6MWT performance at trial 1 and trial 2.
The test-retest reliability of 6-minute walk distances between trials estimated using the ICC2,1 was .98 (95% CI, .97–.99).
The Bland-Altman plot (fig 2) showed no apparent pattern between the mean 6-minute walk distance and differences in 6-minute walk distance at the individual level, and this was supported by a Spearman rank correlation coefficient of .085 (P=.45). The plot revealed 2 outliers: a participant who walked 161m at trial 1 improved by 91m, and another participant who walked 214m at trial 1 deteriorated by 204m. As expected, 95% of the differences were within 2 SDs of the mean.
Fig 2.
Bland-Altman plot.
There were 9 participants whose 6-minute walk distance deteriorated beyond the MDC value (≤–29m, 11%), 62 participants whose 6-minute walk distance remained unchanged (–28m to 28m, 75%), and 12 participants who improved beyond the MDC value (≥29m, 14%) between trial 1 and trial 2. Table 2 presents the characteristics of the participants in each of these categories. There were no statistically significant differences in age, balance, severity of gait deficit, or walking aid used among subgroups, although trends were noted. The subgroup that showed an improvement greater than the MDC tended to have a larger mean 6-minute walk distance at both trial 1 and trial 2 (table 3). In addition, this subgroup was typically younger (mean, 67±12y; P=.052) and more likely to have a mild or moderate gait deficit (P=.065) than the other subgroups. All of the participants with severe gait deficits (n=17) and those who had the highest fall risk (n=5) demonstrated no change between trial 1 and trial 2. The subgroup that tended to deteriorate was older (mean, 76±11y; P=.052) than the other subgroups.
Table 2. Characteristics of Subgroups Classified by MDC (n=83)
| Variable | Difference in 6MWD Between Trial 1 and Trial 2 | |||
|---|---|---|---|---|
| ≤–29m (n=9) | –28m to 28m (n=62) | ≥29m (n=12) | P⁎ | |
| Age (y) | 76±11 | 73±10 | 67±12 | .05 |
| <60y | 1(11) | 2(3) | 3(25) | |
| 60–79y | 5(56) | 48(77) | 8(67) | |
| ≥80y | 3(33) | 12(20) | 1(8) | |
| BBS scores (0–56) | 41±10 | 39±13 | 49±8 | .12 |
| High risk of falls | 0(0) | 5(8) | 0(0) | |
| Medium risk of falls | 4(44) | 25(40) | 1(8) | |
| Low risk of falls | 5(56) | 32(52) | 11(92) | |
| Severity of gait deficit | .06 | |||
| Mild | 3(33) | 23(37) | 5(42) | |
| Moderate | 6(67) | 22(36) | 7(58) | |
| Severe | 0(0) | 17(27) | 0(0) | |
| Walking aid | .51 | |||
| No aid | 3(33) | 27(43.5) | 7(58) | |
| Cane | 6(67) | 27(43.5) | 5(42) | |
| Walker | 0(0) | 8(13) | 0(0) | |
⁎Fisher exact test. |
Table 3. 6MWT Performance of Subgroups Classified by MDC
| Change Defined by MDC⁎ | No. | Mean 6MWD (m) | ||
|---|---|---|---|---|
| Trial 1 | Trial 2 | Difference (Trial 2 – Trial 1) | ||
| Deterioration (change ≥ MDC) | 9 | 201 | 136 | −65 |
| No change (change < MDC) | 62 | 185 | 186 | 1 |
| Improvement (change ≥ MDC) | 12 | 253 | 296 | 43 |
⁎MDC=29m. |
Discussion
This study is among the first conducted to evaluate whether a practice effect exists across repeated trials of the 6MWT in community-dwelling people poststroke. Findings indicate that a practice effect does not occur across 2 trials of the 6MWT within the same evaluation session. This finding may be surprising considering a practice effect has been noted among the healthy elderly and among people with cardiorespiratory ailments. Participants in the current study who improved their 6-minute walk distance beyond the MDC tended to be younger and had less severe gait deficits than those who deteriorated or showed no change.
An average improvement of 20.1±44.5m (66.1±44.5ft) between 2 trials of the 6MWT has been noted among patients with COPD.34 The discrepancy between findings in this compared with the current study may be a result of differences in baseline ability level, test interval, and clinical condition. Participants with COPD walked an average distance of 342.6m at baseline compared with a mean of 196m in the current study. This supports our noted trend that a greater number of participants with high average 6-minute walk distances poststroke tended to improve beyond the MDC compared with those with low average 6-minute walk distances. In the study of people with COPD, participants may have been more rested than those in the current study when performing trial 2 because it was performed the next day and not in a single session. Finally, people with COPD may limit their effort when performing trial 1 in anticipation of disease-related breathlessness and fatigue associated with exercise. After becoming familiar with the protocol and their physiologic response to the test, people with COPD may learn to pace themselves and adapt their performance accordingly to improve in the subsequent trial.
Healthy elderly participants also show a practice effect over repeated trials with progressive improvement between trials 1 and 2 and between trials 2 and 3.16, 31, 32 The 6MWT is considered a submaximal test for this population because the healthy elderly are not limited by cardiorespiratory impairments. These participants likely improve with additional trials as they become increasingly familiar with the testing protocol. Also, because healthy participants are more physically fit, they may have more potential for improvement in repeat trials. However, there may be a ceiling effect to their improvement because of musculoskeletal restrictions or endurance, resulting in a plateau beyond 1 or 2 practice trials. People with stroke who have a mild gait deficit can be compared with the healthy elderly population. It is therefore not surprising that all of the participants who showed an improvement beyond the MDC distance had a mild or moderate gait deficit. Although a third trial was not performed in the current study, it is unlikely that a practice effect would have been observed beyond trial 2 given the high ICC (.98) found between the first 2 trials.
Fatigue may have been responsible for the lack of improvement shown by some individuals with stroke because of the close temporal spacing of the 6MWT trials. A 30-minute rest period may not have been sufficient for full recovery. The American Thoracic Society recommends at least 1 hour between trials to allow adequate recovery.15 Other studies, including those that reported an overall practice effect, have reported a rate of deterioration in 6-minute walk distance similar to that found in the present study.34, 37 More importantly, of those who demonstrated deterioration beyond measurement error in the current study, none were in the subgroup with the most severe gait deficits. This subgroup with the most severe gait deficits would be the most susceptible to fatigue; the fact that this subgroup's performance remained constant suggests that a rest period of 30 minutes was, in fact, adequate.
Another factor that could potentially contribute to the lack of practice effect in the present study is that the corridor used for the 6MWT was only 20m long, as opposed to the recommended 30-m corridor length.15 However, in other studies that evaluated cardiorespiratory and healthy elderly populations and used track lengths greater or less than 20m,31, 32 a practice effect was found. Therefore, the lack of a practice effect does not appear to be a result of the test distance used.
The lack of a practice effect could also be explained by the possibility that the study's participants had been exposed to the 6MWT previously, thereby allowing a practice effect to occur prior to this study. At the time of the original study, however, the 6MWT was not routinely performed in the study centers where the stroke rehabilitation took place.
The subgroup that demonstrated improvements beyond measurement error was younger and more likely to have a mild or moderate gait deficit than the other subgroups. Younger participants with higher BBS scores may not be limited as much by sensorimotor deficits and are likely to have better motor control than their older counterparts. Thus, once familiar with the effort required to complete the test, they may have been able to challenge and pace themselves better, thereby achieving a greater distance on the second test. None of the participants with severe gait deficits (ie, walking speed <0.3m/s) demonstrated change beyond MDC between trials. These participants, who walked the slowest, attained the shortest 6-minute walk distances. The chosen MDC (29m) encompasses a large proportion of these participants' 6-minute walk distances. It would therefore be less likely that their 6-minute walk distances would change by a distance equal to or greater than the MDC compared with participants who walked further. This is consistent with literature demonstrating that MDC may vary across the range of performance scores.57 Therefore, it is possible that higher functioning people with stroke, who are below a certain age cutoff and above a certain threshold in terms of walking speed, may show a practice effect, whereas older, lower functioning people with stroke may not. Thus, a practice walk may be necessary for the former group but not the latter. Further research is warranted to determine whether there are threshold values for age and walking speed, above which a practice effect is likely to occur in people with stroke.
Although poor cardiovascular endurance after stroke is well documented in the literature58, 59, 60, 61 and may influence the presence of a practice effect in this population, performance on the 6MWT seems to be more limited by stroke-related sensory, motor, and balance impairments.12, 26 Potempa et al62 found that when subjects with stroke made improvements in stress test performances after an intervention, this change was related more to recovery in neuromuscular function than aerobic capacity. As mentioned, participants with cardiovascular conditions are able to adjust their speed and performance based on their perceived physiologic response. In contrast, the impairments to neuromuscular control that people with stroke experience are less under voluntary control3 in the absence of sufficient time to allow motor recovery and/or intervention.
Study Limitations
Findings may not be generalizable to people with stroke who did not meet the eligibility criteria for this study. The criteria excluded acute inpatients, those greater than 1 year poststroke, and those not well enough to participate in the intervention secondary to comorbidities.
Conclusions
The primary findings of this study do not support the need for a practice walk with the 6MWT in community-dwelling people in their first year poststroke. No differences were found between those who demonstrated an improvement beyond MDC and those who did not. These findings have important implications for clinicians working in stroke rehabilitation as well as in a research setting. The elimination of a practice trial would save time and reduce participant fatigue, encouraging clinicians to use this reliable and valid measure of functional capacity more frequently. There is a need for future research examining the presence of a practice effect among younger, acute, and noncommunity-dwelling people with stroke, as well as those with only mild gait impairments, to help establish recommendations for clinical practice throughout the continuum of stroke care. Exploration of whether the MDC varies across the range of 6MWT performances would help guide investigation of a practice effect.
Supplier
Acknowledgments
J Liu, C Drutz, R Kumar, L McVicar, and R Weinberger completed this research in partial fulfillment of the requirements for an MScPT degree at the University of Toronto.
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- a Version 14.0; SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.
Reprints not available from the author.
PII: S0003-9993(08)00428-0
doi:10.1016/j.apmr.2008.02.026
© 2008 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
Volume 89, Issue 9 , Pages 1686-1692, September 2008
