Six-minute walk distance in healthy young adults.
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ABSTRACT: Background
The 6-min walk test (6MWT) is a commonly used clinical assessment of exercise capacity in patients with cardiopulmonary or neuromuscular disease, but normal values are lacking for young adults, who are frequent subjects of testing.Methods
In a two-center study, 272 young adults, ages 18-50, underwent American Thoracic Society protocolized 6-min walk testing, and 56 underwent repeat testing. A linear regression model was developed based on anthropomorphic data. This model was compared to existing prediction equations.Results
Median 6MWD for the cohort was 637 m (IQR 584-686 m) and was not significantly impacted by age. This is in contrast to existing equations extrapolated from older subjects that predict increasing 6MWD in younger subjects. We found weak correlation of 6MWD with height, weight, BMI, and resting heart rate. Heart rate at completion correlated most strongly with 6MWD (rho 0.53 p < 0.0001). Repeat 6MWD was surprisingly variable, with a median difference between tests of 32.5 ± 31.9 m. Established reference equations performed poorly in this population, largely because age has much less effect on 6MWD in this group than in older adults.Conclusions
Established reference equations should be reconfigured to include data from young adults, as age has minimal effect on 6MWD in this population. Heart rate response may be a valuable measure of effort in normal subjects. Six-minute walk distance, as with pulmonary function and exercise testing, should have predictive equations across the spectrum of age to allow for accurate assessment of exercise limitation.
SUBMITTER: Halliday SJ
PROVIDER: S-EPMC7174378 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The 6-minute walking test (6MWT) is a simple assessment tool to evaluate exercise capacity. The result of the test is the distance that a subject can walk at a constant and normal pace within 6 minutes (6MWD) and reflects the aerobic/fitness performance related to walking function. Use of 6MWT has been relevant to assess exercise tolerance either in healthy children or in patients with, heart, lung and metabolic diseases. Our aim was to find 6MWT reference values in healthy Italian children. The 6MWT was performed in 5614 children aged 6-11 years recruited from primary Italian schools. Age related reference percentiles of the covered distance were gender-modeled. A linear and quadratic regression model was used to predict 6MWT performance. Males walked longer distances than females, respectively 598.8±83.9 m vs 592.1±77.6 m (p = 0.0016). According to the regression analysis, 6MWD was positively related to age, gender and height, while it was negatively related to body weight [(6MWD = -160.16 + 93.35× age (years) -4.05× age2 (years) +7.34× gender (m) +2.12× weight (kg) -2.50× height (cm)]. Reference values were established for the 6MWT in healthy children. The age related 6MWD percentiles provided a useful tool in the assessment of capacity in 6-11 year children, in fact they may be helpful to evaluate the effect of a given treatment or rehabilitation program and represent a feasible measure as to prevention within the primary school context. It was found a substantial difference from other countries for 6mwd values. In our study, factors such as age, weight and height were relevant for the prediction of 6MWD, similarly to other studies. Therefore, these variables should be taken into account in context of exercise performance.
| S-EPMC6188863 | biostudies-literature
Project description:BackgroundThe six-minute walk test (6MWT) is a safe, simple, inexpensive tool for evaluating the functional exercise capacity of patients with chronic respiratory disease. However, there is a lack of standard reference equations for the six-minute walk distance (6MWD) in the healthy Chinese population aged 18-59 years.AimsThe purposes of the present study were as follows: 1) to measure the anthropometric data and walking distance of a sample of healthy Chinese Han people aged 18-59 years; 2) to construct reference equations for the 6MWD; 3) to compare the measured 6MWD with previously published equations.MethodThe anthropometric data, demographic information, lung function, and walking distance of Chinese adults aged 18-59 years were prospectively measured using a standardized protocol. We obtained verbal consent from all the subjects before the test, and the study design was approved by the ethics committee of Wenzhou People's Hospital. The 6MWT was performed twice, and the longer distance was used for further analysis.ResultsA total of 643 subjects (319 females and 324 males) completed the 6MWT, and average walking distance was 601.6±55.51 m. The walking distance was compared between females and males (578±49.85 m vs. 623±52.53 m; p < 0.0001) and between physically active subjects and sedentary subjects (609.3±56.17 m vs. 592±53.23 m; p < 0.0001). Pearson's correlation indicated that the 6MWD was significantly correlated with various demographic and the 6MWT variables, such as age, height, weight, body mass index (BMI), heart rate after the test and the difference in the heart rate before and after the test. Stepwise multiple regression analysis showed that age and height were independent predictors associated with the 6MWD. The reference equations from white, Canadian and Chilean populations tended to overestimate the walking distance in our subjects, while Brazilian and Arabian equations tended to underestimate the walking distance. There was no significant difference in the walking distance between Korean reference equations and the results of the current study.ConclusionIn summary, age and height were the most significant predictors of the 6MWD, and regression equations could explain approximately 34% and 28% of the distance variance in the female and male groups, respectively.
| S-EPMC5598997 | biostudies-literature
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Project description:BackgroundExercise tolerance in COPD is only moderately well predicted by airflow obstruction assessed by FEV(1). We determined whether other phenotypic characteristics, including CT scan measures, are independent predictors of 6-min walk distance (6MWD) in the COPDGene cohort.MethodsCOPDGene recruits non-Hispanic Caucasian and African American current and ex-smokers. Phenotyping measures include postbronchodilator FEV(1) % predicted and inspiratory and expiratory CT lung scans. We defined % emphysema as the percentage of lung voxels < -950 Hounsfield units on the inspiratory scan and % gas trapping as the percentage of lung voxels < -856 Hounsfield units on the expiratory scan.ResultsData of the first 2,500 participants of the COPDGene cohort were analyzed. Participant age was 61 ± 9 years; 51% were men; 76% were non-Hispanic Caucasians, and 24% were African Americans. Fifty-six percent had spirometrically defined COPD, with 9.3%, 23.4%, 15.0%, and 8.3% in GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages I to IV, respectively. Higher % emphysema and % gas trapping predicted lower 6MWD (P < .001). However, in a given spirometric group, after adjustment for age, sex, race, and BMI, neither % emphysema nor % gas trapping, or their interactions with FEV(1) % predicted, remained a significant 6MWD predictor. In a given spirometric group, only 16% to 27% of the variance in 6MWD could be explained by age, male sex, Caucasian race, and lower BMI as significant predictors of higher 6MWD.ConclusionsIn this large cohort of smokers in a given spirometric stage, phenotypic characteristics were only modestly predictive of 6MWD. CT scan measures of emphysema and gas trapping were not predictive of 6MWD after adjustment for other phenotypic characteristics.
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Project description:Background and objectivesImpaired physical functioning is common and long lasting after an intensive care unit (ICU) admission. The 6-minute walk test (6MWT) is a validated and widely used test of functional capacity. This systematic review synthesizes existing data in order to: (1) evaluate 6-minute walk distance (6MWD) in meters over longitudinal follow-up after critical illness, (2) compare 6MWD between acute respiratory distress syndrome (ARDS) versus non-ARDS survivors, and (3) evaluate patient- and ICU-related factors associated with 6MWD.Data sourcesFive databases (PubMed, EMBASE, Cumulative Index of Nursing and Allied Health Literature, PsychINFO, and Cochrane Controlled Trials Registry) were searched to identify studies reporting 6MWT after hospital discharge in survivors from general (ie, nonspeciality) ICUs. The last search was run on February 14, 2018. Databases were accessed via Johns Hopkins University Library.Data extraction and synthesisPooled mean 6MWD were reported, with separate linear random effects models used to evaluate associations of 6MWD with ARDS status, and patient- and ICU-related variables. Twenty-six eligible articles on 16 unique participant groups were included. The pooled mean (95% confidence interval [CI]) 6MWD results at 3- and 12-months post discharge were 361 (321-401) and 436 (391-481) meters, respectively. There was a significant increase in 6MWD at 12 months compared to 3 months (P = .017). In ARDS versus non-ARDS survivors, the mean (95% CI) 6MWD difference over 3-, 6-, and 12-month follow-up was 73 [13-133] meters lower. Female sex and preexisting comorbidity also were significantly associated with lower 6MWD, with ICU-related variables having no consistent associations.ConclusionsCompared to initial assessment at 3 months, significant improvement in 6MWD was reported at 12 months. Female sex, preexisting comorbidity, and ARDS (vs non-ARDS) were associated with lower 6MWT results. Such factors warrant consideration in the design of clinical research studies and in the interpretation of patient status using the 6MWT.
| S-EPMC7442114 | biostudies-literature
Project description:Background: To date, there is no reference for a 6-min walk test distance (6-MWD) immediately after cardiac surgery. Therefore, this study aimed to identify the determinants and to generate equations for prediction reference for 6-MWD in patients immediately after cardiac surgery. Methods: This is a cross-sectional study of the 6-min walk test (6-MWT) prior to participation in the cardiac rehabilitation (CR) program of patients after coronary artery bypass surgery (CABG) or valve surgery. The 6-MWT were carried out in a gymnasium prior to the CR program immediately after the cardiac surgery. Available demographic and clinical data of patients were analyzed to identify the clinical determinants of 6-MWD. Results: This study obtained and analyzed the data of 1,509 patients after CABG and 632 patients after valve surgery. The 6-MWD of all patients was 321.5 ± 73.2 m (60-577). The distance was longer in the valve surgery group than that of patients in the CABG group (327.75 ± 70.5 vs. 313.59 ± 75.8 m, p < 0.001). The determinants which significantly influence the 6-MWD in the CABG group were age, gender, diabetes, atrial fibrillation, and body height, whereas in the valve surgery group these were age, gender, and atrial fibrillation. The multivariable regression models generated two formulas using the identified clinical determinants for patients after CABG: 6-MWD (meter) = 212.57 + 30.47 (if male gender) - 1.62 (age in year) + 1.09 (body height in cm) - 12.68 (if with diabetes) - 28.36 (if with atrial fibrillation), and for patients after valve surgery with the formula: 6-MWD (meter) = 371.05 + 37.98 (if male gender) - 1.36 (age in years) - 10.61 (if atrial with fibrillation). Conclusion: This study identified several determinants for the 6-MWD and successively generated two reference equations for predicting 6-MWD in patients after CABG and valve surgery.
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Project description:The six-minute walk test (6MWT) is a widely used test for the indirect measurement of cardiorespiratory fitness in various cancer populations. Although the 6MWT is a simple test, there are no normative values for breast cancer survivors (BCS) or comparisons of results with healthy counterparts. A systematic review with a meta-analysis was carried out, which included studies from 2007 to 2020. Ninety-one studies were found, 21 of which were included in the quantitative synthesis. Among them were 9 randomized controlled trials (RCT), 8 prospective cohort studies and 4 cross-sectional studies. A total of 1084 BCS were included. Our results revealed that healthy subjects (n = 878) covered a significantly greater distance than BCS during the 6MWT (589.9 m vs. 477.4 m, p < 0.001), and the results of the meta-regression analysis showed that the 6MWD was predicted by the participants' BMI (p < 0.001), but not by their age (p = 0.070). After adjustment for BMI, the healthy subjects also covered greater distances than the BCS (103 m; p < 0.001). The normative values of 6MWT were presented for BCS. Besides, 6MWT distances distinguish between their healthy counterparts, therefore, the 6MWT distance is a relevant parameter for the assessment and monitoring of cardiorespiratory fitness in medical and exercise interventions for BCS.
| S-EPMC7967367 | biostudies-literature
Project description:Background and objectiveAlthough the six-minute walk test (6MWT) is widely used as a measure of exercise capacity, it may not be applicable in some settings and populations. This issue has led to increased use of the two-minute walk test (2MWT) to assess exercise capacity. The main objective of this study is to establish reference equations for the two-minute walk distance (2MWD) in healthy Chinese adults aged 18-85 years.MethodsA total of 973 volunteers took part in the study. We obtained verbal consent from all participants before the test, and the study design was approved by the ethics committees of Wenzhou People's Hospital. The participants performed two 2MWTs using a standardized protocol, and the longer distance was used for further analysis. Stepwise multiple regression analysis was performed using age, height and weight as independent variables and was used to establish the reference equations for the 2MWD in the male and female groups.ResultsThe mean walking distance for all participants was 199.1±25.81 m. Age and height were identified as independent factors that influenced the 2MWD, and they explained 35% and 34% of the variance in distance for the male and female groups, respectively.ConclusionThis study resulted in determination of reference equations for predicting the 2MWD in healthy Chinese adults. These 2MWD standards will provide useful references for medical care in some settings and populations.
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Project description:Background:In patients with ischaemic left ventricular dysfunction, coronary artery bypass surgery (CABG) may decrease mortality, but it is not known whether CABG improves functional capacity. Objective:To determine whether CABG compared with medical therapy alone (MED) increases 6?min walk distance in patients with ischaemic left ventricular dysfunction and coronary artery disease amenable to revascularisation. Methods:The Surgical Treatment in Ischemic Heart disease trial randomised 1212 patients with ischaemic left ventricular dysfunction to CABG or MED. A 6?min walk distance test was performed both at baseline and at least one follow-up assessment at 4, 12, 24 and/or 36?months in 409 patients randomised to CABG and 466 to MED. Change in 6?min walk distance between baseline and follow-up were compared by treatment allocation. Results:6?min walk distance at baseline for CABG was mean 340±117?m and for MED 339±118?m. Change in walk distance from baseline was similar for CABG and MED groups at 4 months (mean +38?vs +28?m), 12 months (+47?vs +36?m), 24 months (+31?vs +34?m) and 36 months (-7 vs +7?m), P>0.10 for all. Change in walk distance between CABG and MED groups over all assessments was also similar after adjusting for covariates and imputation for missing values (+8?m, 95% CI -7 to 23?m, P=0.29). Results were consistent for subgroups defined by angina, New York Heart Association class ?3, left ventricular ejection fraction, baseline walk distance and geographic region. Conclusion:In patients with ischaemic left ventricular dysfunction CABG compared with MED alone is known to reduce mortality but is unlikely to result in a clinically significant improvement in functional capacity. Trial registration number:NCT00023595.
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Project description:The six-minute walk test is widely used to assess the severity and prognosis of pulmonary hypertension. However, the pathophysiology underlying a compromised six-minute walk distance is incompletely characterized. The purpose of this study is to evaluate the Fick principle and pulmonary hemodynamic determinants of the six-minute walk distance in patients with suspected pulmonary hypertension. Twenty-nine patients were retrospectively studied and underwent a right heart catheterization for the evaluation of suspected pulmonary hypertension. With the pulmonary artery catheter in place, patients were moved to a treadmill and completed a six-minute walk test. Fick cardiac output and indices of right heart afterload were calculated using continuous measurements of pulmonary vascular pressures, gas exchange, and mixed venous blood samples. Fifteen subjects who walked ≤ 348 m were compared to 14 subjects who walked > 348 m. Systemic oxygen delivery was impaired in six-minute walk distance ≤ 348 m compared to six-minute walk distance > 348 m (15.2 ± 6.2 vs. 23.2 ± 6.8 mL/kg/min, p < 0.01). Impaired oxygen delivery was due to a depressed cardiac index and decreased cardiac reserve demonstrated by the change in the stroke volume index (3.0 ± 14 vs. 17 ± 15 mL/min/m2, p = 0.02). The six-minute walk distance positively correlated with oxygen delivery (r = 0.501, p = 0.006) and inversely correlated with oxygen extraction (r = 0.369, p = 0.049). A decreased six-minute walk distance was associated with an increased total pulmonary resistance (r = 0.502, p = 0.006) and pulmonary vascular resistance (r = 0.530, p = 0.003). In patients with suspected pulmonary hypertension, a decreased six-minute walk distance is due to compromised oxygen delivery, decreased cardiac reserve, and increased right ventricular afterload.
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