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A comparison of the shuttle and 6 minute walking tests with measured peak oxygen consumption in patients with heart failure.

This study investigated the use of an incremental, externally-paced 10 m shuttle walk test (SWT) as an objective, reliable and predictive test of functional capacity in patients with heart failure (CHF). The SWT was compared to a 6 minute walk test (6WT) and a maximal symptom-limited treadmill peak oxygen consumption (VO2peak) test. Experiment 1 examined the reproducibility of the SWT. Two SWF trials were performed and distance ambulated (DA), heart rate (HR) and rate of perceived exertion (RPE) results compared. In experiment 2, SWT, 6WT, and VO2 peak tests were performed and HR. RPE and ambulatory VO2 compared. The SWT demonstrated strong test/retest reliability for DA (r = 0.98). HR (r = 0.96) and RPE (r = 0.89). Treadmill VO2 peak was significantly correlated with DA during the SWT (r = 0.83, P < 0.05), but not the 6WT. SWT peak VO2 (18.5 +/- 1.8 ml.kg(-1) x min(-1)) and treadmill VO2 peak (18.3 +/-2.0 ml.kg(-1) x min(-1)) were also highly correlated (r = 0.78, P < 0.05). Conversely, 6WT peak VO2 and treadmill VO2 peak were not significantly correlated. This study suggests the SWT is a reliable, objective test, highly predictive of VO2 peak which may be a more optimal field exercise test than the self paced 6WT.

Exercise Test↗

Hormonal responses to the 6-minute walk test in women and men with coronary heart disease: a pilot study.

BACKGROUND: Women with coronary heart disease (CHD) are more likely than men to develop congestive heart failure (CHF). Dysregulation of sympathetic and volume-regulatory hormones may contribute to the onset of symptomatic CHF. We hypothesized that this hormonal dysregulation develops at an earlier stage of CHD in women than in men. OBJECTIVES: The study goals were (1) to determine the effect of gender on basal and exercise-induced plasma concentrations of catecholamines and volume-regulatory hormones in patients diagnosed with CHD, New York Heart Association class I and (2) to determine efficacy of the 6-minute walk test as a stimulus for release of these hormones. METHODS: Study participants were 9 women and 9 men with normal left ventricular ejection fraction (>50%) and CHD confirmed by arteriography. Data were collected under resting conditions, and after the 6-minute walk test, in the general clinical research center of a northeastern university medical center. RESULTS: Basal plasma vasopressin (VP) concentration was significantly higher in men than in women (P = .018). Exercise, for women and men combined, significantly increased atrial natriuretic peptide (P < .0005), VP (P = .04), norepinephrine (P < .0005), and epinephrine (P = .038) but not plasma renin activity (P = .09). No further gender differences were detected for basal levels, or for the magnitude of exercise-induced increases, for any of the hormones measured. CONCLUSIONS: The 6-minute walk test is an exercise of sufficient intensity and duration to initiate the release of hormones associated with sympathetic activation and fluid-electrolyte regulation in both women and men with CHD. It appears that a gender difference was detected only for basal VP levels.

Atrial Natriuretic Factor↗

Idiopathic pulmonary fibrosis: prognostic value of changes in physiology and six-minute-walk test.

RATIONALE AND HYPOTHESIS: Idiopathic pulmonary fibrosis is a fatal disease with a variable rate of progression. We hypothesized that changes in distance walked and quantity of desaturation during a six-minute-walk test (6MWT) would add prognostic information to changes in FVC or diffusing capacity for carbon monoxide. METHODS: One hundred ninety-seven patients with idiopathic pulmonary fibrosis were evaluated. Desaturation during the 6MWT was associated with increased mortality even if a threshold of 88% was not reached. Baseline walk distance predicted subsequent walk distance but was not a reliable predictor of subsequent mortality in multivariate survival models. The predictive ability of serial changes in physiology varied when patients were stratified by the presence/absence of desaturation < or = 88% during a baseline 6MWT. For patients with a baseline saturation < or = 88% during a 6MWT, the strongest observed predictor of mortality was serial change in diffusing capacity for carbon monoxide. For patients with saturation > 88% during their baseline walk test, serial decreases in FVC and increases in desaturation area significantly predicted subsequent mortality, whereas decreases in walk distance and in diffusing capacity for carbon monoxide displayed less consistent statistical evidence of increasing mortality in our patients. CONCLUSION: These data highlight the importance of stratifying patients by degree of desaturation during a 6MWT before attributing prognostic value to serial changes in other physiologic variables.

Aged↗

Reliability and intensity of the six-minute walk test in healthy elderly subjects.

PURPOSE: The 6-min walk test (6-MWT) is an easy and validated field test, generally used in patients to assess their physical capacity. We think that the 6-MWT could also be conducted in the same perspective in healthy subjects, aged 60-70 yr. However, little is known about the effect of the familiarization on the 6-MWT performance and the relative intensity of this test. The aims of this study were therefore to bring precision to the 6-MWT reliability and intensity in this population. METHODS; Over 3 d, 12 subjects performed two maximal exercise tests on treadmill and five 6-MWT (two in the morning and three in the afternoon) with a portable metabolic measurement system (Cosmed K4, Rome, Italy). The distance, walking speed, oxygen uptake (VO2 (max)), and heart rate (HR) values were measured during the 6-MWT. RESULTS: Distance, walking speed, and VO2(max) were only lower during the first two 6-MWT (respectively, P< 0.001, P< 0.001, and P< 0.05). HR was reliable from the first 6-MWT and was higher during the tests performed in the afternoon (P< 0.001). The intensity of the 6-MWT corresponded to 79.6 +/- 4.5% of the VO2(max), 85.8 +/- 2.5% of the HR (max), and 78.0 +/- 6.3% of the HR (reserve). Moreover, it was higher than the ventilatory threshold in each subject (P< 0.01). CONCLUSION: In healthy elderly subjects, the 6-MWT represents a submaximal exercise, but at almost 80% of the VO2(max). To be exploitable, two familiarization attempts are required to limit the learning effect. Finally, the 6-MWT time of day must be taken into account when assessing HR.

Aged↗

Effort-limited treadmill walk test: reliability and validity in subjects with postpolio syndrome.

OBJECTIVE: To determine the reliability and construct validity of an effort-limited treadmill walk test to measure functional ability in subjects with postpolio syndrome in an outpatient postpolio clinic. DESIGN: Functioning and distance walked on a treadmill to a Borg "hard" effort level were measured three times, a week apart, by two blinded raters in 15 subjects with postpolio syndrome, aged 37-67 yrs, with new weakness, fatigue, and pain but with no other cause of symptomatology or condition-limiting walking. One rater tested them twice. Fatigue activity level, mobility, and health-related quality of life (Medical Outcome Study Short Form Health Survey [SF-36]) defined functioning. Generalizability correlation coefficients determined intrarater, test-retest and interrater reliability. The correlations relating the distance walked and functioning determined construct validity. RESULTS: Reliability for generalizability correlation coefficients were: intrarater, 0.91; test-retest, 0.85; and interrater, 0.58. Interrater reliability improved to 0.91 with adherence to a standardized protocol. Validity was established with correlations between the distance walked and SF-36 physical component score (0.66), physical role (0.60), bodily pain (0.60), and vitality (0.55). CONCLUSIONS: The treadmill walk test provides a reproducible and valid measure of ability in persons with postpolio syndrome with a single rater, but a standardized protocol is essential for reliability.

Adult↗

Effects of strength training on cardiovascular responses during a submaximal walk and a weight-loaded walking test in older females.

PURPOSE: The purpose of this study was to examine the effects of a total body strength training program on oxygen uptake (VO2), heart rate (HR), systolic blood pressure (SBP), and rate pressure product (RPP) during a submaximal walk and a weight-loaded walking test in healthy women 60-77 years old. METHODS: The submaximal walk (2 mph and 3.5% grade) took place during stage 3 of a graded exercise test. The weight-loaded walking task consisted of treadmill walking at 2 mph while carrying a box weighing 40% of maximum isometric elbow flexion strength. The women strength trained three times per week for approximately 1 hour per session for 16 weeks. RESULTS: Paired t tests determined that strength increased by 57% on six isotonic strength tests (one repetition maximum) and by 29% on two isometric strength tests. A repeated measures analysis of variance (ANOVA) was used to determine the pre- to post-differences between and within the two tests (alpha = 0.05). There was no change in VO2 but HR, SBP, and RPP decreased significantly during the submaximal walk and the weight-loaded walking test. However, average HR (135 to 120 bpm) and RPP (23.3 x 10(3) to 19.3 x 10(3)) decreased more during the weight-loaded walking test than during the submaximal walk (HR: 108 to 104 bpm; RPP 18.3 x 10(3) to 17.0 x 10(3)). CONCLUSIONS: In conclusion, the reduced HR, SBP, and RPP indicates that strength training may reduce cardiovascular stress during daily tasks in healthy older women.

Age Factors↗

Clinical reliability of the 6 minute corridor walk test performed within a week of a myocardial infarction.

The 6 minute walk test (6 MWT) has been shown to provide a clinically useful index of functional capacity in chronic heart failure. We hypothesized that similar results would be found in patients who had a recent (ie, within a week) myocardial infarction (MI). Twenty-five patients (23 males, aged 43 to 72 years) who had undertaken an exercise stress test without complications underwent 3 consecutive 6 MWTs (1 hour apart). Heart rate, systolic and diastolic blood pressure, the level of perceived exertion (Borg scale), and the walking distance were determined. In addition, chest pain was assessed by a 0 to 10 numerical rating scale (NRS) and the ECG was continuously monitored. All subjects were able to successfully complete the exercise tests without major cardiovascular complications: mild chest pain (NRS 1 to 3) was found in 3 patients. A Bland-Altman analysis revealed that the mean bias +/- 95% confidence interval of the differences on distance walked between test 2 - test 1 were substantially higher than test 3 - test 2 differences (18 +/- 66 m and 6 +/- 41 m, respectively). The intraclass correlation coefficients were consistently high for all physiological and sensorial responses at the end of the 6 MWTs (range, 0.75 to 0.95). The 6 MWT is a safe and reproducible measurement of functional capacity in stable patients after a noncomplicated MI, even when performed within a week of the event. Therefore, this test might be useful for the evaluation of exercise tolerance in phases I and II of inpatient cardiovascular rehabilitation programs or to assess functional responses to selected interventions.

Adult↗

Effects of maximally tolerated oral therapy on the six-minute walking test in patients with chronic congestive heart failure secondary to either ischemic or idiopathic dilated cardiomyopathy.

In patients with heart failure, therapy with "maximally tolerated" oral doses of diuretics, vasodilators, and digitalis results in a significant increase in the distance walked during the 6-minute walking test, compared with conventional therapy at "standard" doses, indicating an improvement in exercise tolerance. The 6-minute walk test is a simple, inexpensive, and well-tolerated test to measure changes in exercise tolerance induced by pharmacologic interventions, even on a short-term basis.

Administration, Oral↗

Comparison between an indoor and an outdoor 6-minute walk test among individuals with chronic obstructive pulmonary disease.

OBJECTIVES: To investigate the feasibility of an outdoor 6-minute walk test (6MWT) as a measure of functional status among individuals with chronic obstructive pulmonary disease (COPD), and to examine the relationship between performance on an indoor and an outdoor 6MWT. DESIGN: An experimental, repeated-measures crossover design. Subjects were studied on 2 separate days in the same week. Two 6MWTs-one indoors and the other outdoors-were performed on each study day, with a rest in between. The test order was randomly selected on the first day and reversed on the second day. Outdoor tests were performed on days of moderate weather conditions (mean temperature +/- standard deviation, 21 degrees +/-3 degrees C; mean wind speed, 15+/-7km/h; no precipitation) and on a flat surface (sidewalk). SETTING: Outpatient rehabilitation program in Ontario. PARTICIPANTS: Eighteen subjects with COPD (10 men, 8 women; age, 70+/-8y), 5 using supplemental oxygen at rest (forced expiratory volume in 1s, 1.0+/-0.3L; 42%+/-8% of predicted). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Distance walked in 6 minutes (in meters), duration of rest (in seconds), and change in rate of perceived dyspnea. RESULTS: There was no significant effect of setting (indoors vs outdoors) on distance walked (394+/-86m vs 398+/-84m, P=0.4), duration of rest (13+/-28s vs 9+/-20s, P=0.4), or change in rate of perceived dyspnea (2.3+/-1.7 vs 2.3+/-2.0, P=0.8). Testing day had no significant effect on walk test performance (all P>0.1). CONCLUSIONS: The results indicate that the 6MWT performed outdoors within reasonable climatic parameters may be reflective of 6MWT performance indoors.

Aged↗

Effect of bariatric surgery on the six-minute walk test in severe uncomplicated obesity.

BACKGROUND: The six-minute walk test (6mWT) is a simple index of functional capacity in healthy people, and it has been used to estimate exercise capacity in obese subjects. The aim of this study was to determine whether weight reduction induced by laparoscopic adjustable gastric banding (LAGB) improves the functional capacity in the severely obese on the 6mWT. METHODS: A prospective 1-year study was carried out at the Hospital Casoria, Naples, involving 15 consecutive severely obese patients who underwent the 6mWT before and 1 year after LAGB. BMI, walking distance, heart rate, dyspnea, and respiratory function tests were also measured. Patients served as their own controls. RESULTS: 15 patients (all females) were evaluated. Mean BMI decreased from 42.1 (range 39-49) before to 31.9 (range 25-38) postoperatively. The distance walked increased from 475.7 meters (range 380-580) before LAGB to 626.3 meters (range 435-880) 1 year postoperatively (P < 0.0001), and the dyspnea score after the 6mWT was significantly reduced postoperatively. All functional variables after the 6mWT showed improvement postoperatively at 1 year study. CONCLUSION: Weight reduction in the obese increases the functional capacity during walking. The improvements are refected in the patients' own assessment.

Adult↗

Walk test at increased levels of heart rate in patients with dual-chamber pacemaker and with normal or depressed left ventricular function.

BACKGROUND: This study focuses the role of heart rate on cardiac output (CO) at rest and during walk test in patients with dual-chamber pacemaker and depressed or normal left ventricular (LV) function. METHODS AND RESULTS: In nine patients with ejection fraction (EF) <50% (group A) and in seven with EF 50% (group B) haemodynamics were assessed at rest and during three randomized 6-min walk tests at fixed rate of 70, 90, and 110beats.min(-1). All patients had dual-chamber pacemaker implanted for complete heart block. Left ventricular function was monitored by a radionuclide system. In group A, with increasing pacing-rate from 70 to 110beats.min(-1), CO did not change both at rest and during walk, whereas end-systolic volume (ESV) increased (P<0.05) and stroke volume (SV) decreased from 68+/-6 to 47+/-9ml at rest (P<0.0001) and from 112+/-21 to 76+/-17ml during walk (P<0.005). In group B, with increasing pacing-rate, CO rose from 6.4+/-0.7 to 9.1+/-1.6l.min(-1)at rest (P<0.001) and from 10+/-1.5 to 14.1+/-2.2l.min(-1)during walk (P<0.0001), with no change in ESV and SV. CONCLUSIONS: Increasing heart rate in presence of ventricular asynchrony induced by dual-chamber pacing has negative effect on cardiac contractility and does not improve CO at rest or during physical activity in patients with depressed LV function as occurs in those with normal function.

Aged↗

A 2-km walking test for assessing the cardiorespiratory fitness of healthy adults.

A simple walking test was developed with 159 (females = 80, males = 79) healthy 20-65-year-old subjects. All the subjects first walked the distances of 1.0, 1.5 and 2.0 km on a flat dirt road. Half of the participants were tested in the laboratory for maximal oxygen uptake (VO2max), and the 2-km test was repeated again twice. In a comparison of the three distances, the 2-km test was repeatable, the most preferable subjectively and the most accurate in predicting VO2max. A sex-specific prediction model including walking time, heart rate at the end of the walk, age and body mass index predicted 73-75% of the variance in VO2max (ml.kg-1.min-1) and that with body weight 66-76%, with a standard error of estimate of the order of 9-15% of the mean. The cross-validation of the models yielded reasonable accuracy in obese men and women and in moderately active men, and less accuracy in moderately active women and highly active men. These results suggest that a fast 2-km walk supplemented with simple measurements is a feasible and accurate alternative for determining the cardiorespiratory fitness of healthy adults.

Adult↗

Prediction of outcome by neurohumoral activation, the six-minute walk test and the Minnesota Living with Heart Failure Questionnaire in an outpatient cohort with congestive heart failure.

AIMS: To compare the precursor of atrial and brain natriuretic peptide (N-ANP, N-BNP), brain natriuretic peptide (BNP), big endothelin-1, the 6-min walk test and the Minnesota Living with Heart Failure Questionnaire (LHFQ) with regard to short-term outcome in an ambulatory heart failure population. METHODS AND RESULTS: Ninety-six individuals (left ventricular ejection fraction of 26+/-10%) were included in the study. Within 1 day blood samples of N-ANP, N-BNP, BNP and big endothelin-1 were obtained, and the 6-min walk test and LHFQ were measured. The predictive power of these variables - including renin-angiotensin system antagonist therapy - in respect of 1-year event-free survival were calculated with a Cox regression analysis. All investigated variables had the power to predict outcome in a univariate analysis. Multivariate analysis revealed that N-ANP (chi-square=58 P<0.0001), BNP (chi-square=8 P<0.01), the LHFQ (chi-square=6 P<0.02) and the renin-angiotensin system antagonist (chi-square=4 P<0.05), are independent predictors. CONCLUSION: We conclude that, in an open clinical cohort of patients with large differences in the progression of the disease, N-ANP, BNP and LHFQ are the most reliable predictors of worsening heart failure in the short term. However, the dosage of the ACE inhibitor influenced short-term survival in this population.

Activities of Daily Living↗

Assessment of oxygen uptake during the 6-minute walking test in patients with heart failure: preliminary experience with a portable device.

In patients with heart failure, the 6-minute walking test (6-MWT) is considered a useful measure of submaximal exercise capacity. Few data are available on oxygen uptake (VO2) during a standard 6-MWT. The aim of this study was to measure the 6-MWT VO2 by using a recently validated portable instrument in 26 patients (24 men, 2 women; mean age, 56 +/- 11 years) with mild to severe heart failure (New York Heart Association class II, 10 patients; III, 10 patients; IV, 6 patients; left ventricular ejection fraction: 22 +/- 6%). Peak VO2 was measured during a symptom-limited cardiopulmonary exercise test performed in a period of 1 to 3 days (10 watt/m increment). Peak VO2 was 15 +/- 4 ml/kg/m during the symptom-limited test and 12.9 +/- 4.4 ml/kg/m during the 6-MWT (p < 0.05), corresponding to 86% of peak VO2. Seven (27%) of 26 patients showed a 6-MWT VO2 equal to or higher than peak VO2. Anaerobic threshold (AT) was identified in 23 of 26 patients during maximal exercise and in 19 of 26 patients during the 6-MWT; VO2 at AT was similar in the two tests (12.2 +/- 3.5 ml/kg/m vs 11.9 +/- 4.2 ml/kg/m). The distance walked during the 6-MWT (mean, 418 +/- 20 m) significantly correlated with 6-MWT VO2 (r = 0.71) and peak VO2 (r = 0.63); the 6-MWT VO2 also showed a high correlation with peak VO2 (r = 0.86). Thus in patients with failing hearts, VO2 during 6-MWT (considered a classic submaximal exercise) is, on average, only 15% lower than peak VO2 and is largely supported by anaerobic metabolism (work above the anaerobic threshold).

Adult↗

Reproducibility of the six-minute walking test in chronic heart failure patients.

The six-minute walking test (WT) is used in trials and clinical practice as an easy tool to evaluate the functional capacity of chronic heart failure (CHF) patients. As WT measurements are highly variable both between and within individuals, this study aims at assessing the contribution of the different sources of variation and estimating the reproducibility of the test. A statistical model describing WT measurements as a function of fixed and random effects is proposed and its parameters estimated. We considered 202 stable CHF patients who performed two baseline WTs separated by a 30 minute rest; 49 of them repeated the two tests 3 months later (follow-up control). They had no changes in therapy or major clinical events. Another 31 subjects performed two baseline tests separated by 24 hours. Collected data were analysed using a mixed model methodology. There was no significant difference between measurements taken 30 minutes and 24 hours apart (p = 0.99). A trend effect of 17 (1.4) m (mean (SE)) was consistently found between duplicate tests (p < 0.001). REML estimates of variance components were: 5189 (674) for subject differences in the error-free value; 1280 (304) for subject differences in spontaneous clinical evolution between baseline and follow-up control, and 266 (23) for the within-subject error. Hence, the standard error of measurement was 16.3 m, namely 4 per cent of the average WT performance (403 m) in this sample. The intraclass correlation coefficient was 0.96. We conclude that WT measurements are characterized by good intrasubject reproducibility and excellent reliability. When follow-up studies > or = 3 months are performed, unpredictable changes in individual walking performance due to spontaneous clinical evolution are to be expected. Their clinical significance, however, is not known.

Adult↗

Development of a single-stage submaximal treadmill walking test.

An equation was developed to estimate maximal oxygen uptake (VO2max, ml.kg-1.min-1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20-59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0-4.5 mph) and then performed a VO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate VO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg-1.min-1): VO2max = 15.1 + 21.8*SPEED (mph) -0.327*HEART RATE (bpm) -0.263*SPEED*AGE (yr) + 0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male). The constant and all coefficients were highly significant (P less than 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated VO2max value was obtained using the above model. Estimated VO2max then was regressed on observed VO2max yielding the following equation (R2 = 0.92): ESTIMATED VO2max = 0.15 + 1.03*OBSERVED VO2max. The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of +/- 5 ml.kg-1.min-1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.

Adult↗

Do functional walk tests reflect cardiorespiratory fitness in sub-acute stroke?

BACKGROUND AND PURPOSE: The Six-Minute Walk Test (6MWT) has been employed as a measure of functional capacity, but its relationship to cardiorespiratory fitness in stroke is not well established. Gait speed measured over short distances is commonly used as an index of walking competency following stroke. We evaluated the relationship between the 6MWT, aerobic fitness (VO2peak) and walking competency in sub-acute stroke. METHODS: Thirty-six individuals (mean age +/- SD, 64.6 +/- 14.4 years; time post-stroke 16.2 +/- 13.3 days) were evaluated using the 6MWT (distance, speed, heart rate), a maximal exercise test (VO2peak, heart rate, exercise test duration), and walking competency using a five meter walk (speed, symmetry ratio). Correlation analyses were used to examine the relationships between these outcomes. RESULTS: There was a strong correlation between the 6MWT and five meter walk velocity for preferred (r = 0.79) and fast (r = 0.82) speed (p < 0.001). On average, the 6MWT speed was faster than the preferred gait speed (94.9 cm/s vs. 83.8 cm/s, p = 0.003), but slower than the fast-paced walk (115.1 cm/s, p < 0.001). There was significant though more moderate association between 6MWT distance and VO2peak (r = 0.56, p < 0.001) and exercise test duration (r = 0.60, p < 0.001). CONCLUSION: The speed selected during the 6MWT was strongly related to the velocities selected during the five meter walk distance (intermediate to the selected preferred and fast speeds). Although the 6MWT may be challenging to the cardiorespiratory system, it appears to be more strongly influenced by potential limits to walking speed rather than cardiorespiratory capacity. As a result, this test is not, by itself, an adequate measure of aerobic fitness early after stroke.

Journal Article↗

Reliability of a timed walk test in persons with acquired brain injury.

OBJECTIVE: The purpose of this study was to assess the reliability of a 6-min walk test in individuals with acquired brain injury. DESIGN: A total of 23 clients (14 men, 9 women) participated. All participants were clients in a postacute residential rehabilitation facility. The time from injury averaged 12 mo (range, 7-38 mo). Subjects were instructed to walk around a rectangular track as many times as possible during a period of 6 min. The test was performed twice, separated by 1-10 days. Heart rate was monitored continuously throughout the test, and distance traveled was recorded in meters after completion. A physiologic cost index (beats per meter) was calculated. Intraclass correlation coefficients were calculated for distance traveled, heart rate responses, and physiologic cost index. RESULTS: The mean distance walked was 403 +/- 105 m (trial 1) and 417 +/- 106 m (trial 2). The intraclass correlation coefficient for distance was 0.94. The mean steady-state heart rate was 118 +/- 21 beats/min (trial 1) and 117 +/- 20 beats/min (trial 2), and the intraclass correlation coefficient was 0.65. The mean physiologic cost index was 0.52 +/- 0.19 beats/m (trial 1) and 0.55 +/- 0.22 beats/m (trial 2), and the intraclass correlation coefficient was 0.89. CONCLUSIONS: Distance traveled and the physiologic cost index demonstrated excellent reliability, whereas heart rate responses for individual minutes demonstrated only fair reliability. The individuals studied were very consistent in their efforts, despite a combination of physical and cognitive impairments. The results suggest that the 6-min walk test can be used reliably in the assessment of functional ambulation in persons with acquired brain injury.

Adolescent↗