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# 6 Minute Walk Distance

Calculators  Multiple body systems
6 minute walk test (6MWT) is for measuring the response to medical interventions in patients with moderate to severe heart or lung disease. It evaluates the global and integrated responses of all the systems involved during exercise, including the pulmonary and cardiovascular systems, systemic circulation, peripheral circulation, blood, neuromuscular units, and muscle metabolism.
Gender
Male
Female
Height
c
Age
y
Weight
k
Distance Walked
alternative, to figure out percentage of expected
m
Result:

## Background

Measured Factor
Functional capacity of patient
Measured Factor Disease
• Reduced pulmonary function
• altered cardiac function
• ankle–arm index
• muscle strength
• nutritional status
• orthopedic function
• cognitive function.
Measured Factor Detail
6MWT is performed as a single test to assess the functional status of the patient or it may be repeated to evaluate the impact of medical intervention (change in treatment regimen, rehabilitation, oxygen supplementation) on the patient’s exercise performance
Speciality
Multi-Speciality
Body System
Multiple body systems
Formula
Males: 6MWD in meters = (7.57 × height in cm) – (5.02 × age) – (1.76 × weight in kg) – 309. Lower limit of normal = 6MWD - 153. Females: 6MWD in meters = (2.11 × height in cm) – (2.29 × weight in kg) – (5.78 × age) + 667. Lower limit of normal = 6MWD - 139
Measured Factor Low Impact
• Low values obtained in this test indicate reduced efficiency of all the systems involved during exercise, including the pulmonary and cardiovascular systems, systemic circulation, peripheral circulation, blood, neuromuscular units, and muscle metabolism
• It does not provide specific information on the function of each of the different organs and systems involved in exercise or the mechanism of exercise limitation.
Measured Factor High Impact
• Normal functional capacity of patient
Preparation
• Patients should not have exercised vigorously within 2 hours of beginning the test
• Appropriate shoes for walking should be worn
• Patient’s usual medical regimen should be continued.

### Result Interpretation

Ranges Ranges
• Normal: Results vary according to gender, age, height and weight.
• Normal Adult Male: 6 MWT result is associated with age, gender, continent and anthropometric variables. The weighted average of the distance during 6MWT is 619.8 m.
Result Low Conditions
• Declined functional capacity of patient with cystic fibrosis
• heart failure
• peripheral vascular disease
• lung transplant
• COPD
• This test is also helps to predicts morbidity and mortality after heart and lung disease.
False Positive
• Older age
• Shorter height
• Female sex
• presence of dysfunction in cardiovascular, pulmonary and musculoskeletal systems
• Impaired cognition.
Test Limitations
6MWT does not provide specific information on the function of each of the different organs and systems involved in exercise or the mechanism of exercise limitation, as is possible with maximal cardiopulmonary exercise testing. The self-paced 6MWT assesses the submaximal level of functional capacity. Most patients do not achieve maximal exercise capacity during the 6MWT.

### Studies

Study Validation 1
The aim of this work was to investigate the short- and long-term test-retest reliability of the 6-min walk distance (6MWD), peak heart rate, and nadir oxygen desaturation in idiopathic pulmonary fibrosis (IPF). A reliability study of 70 adults with IPF was undertaken within outpatient pulmonary rehabilitation programs at 2 tertiary hospitals. Participants completed 2 baseline 6-min walk tests using a standard protocol, with continuous measures of percutaneous SpO2 and heart rate via pulse oximetry. The 6-min walk test was completed immediately following an intervention period and 6 months after. Reproducibility was assessed by intraclass correlation coefficient and Bland-Altman analysis. The results of the study demonstrate that 6MWD is a reproducible measure of exercise capacity in people with IPF.
References: 2
Study Validation 2
The study aimed to confirm the performance characteristics and estimates of minimal clinically important difference (MCID) of 6MWD in an independent cohort of patients with  idiopathic pulmonary fibrosis (IPF). The study included patients randomized to placebo in the phase 3 CAPACITY trials who had a baseline 6MWD measurement were included in these analyses. The 6MWD and other functional parameters (lung function, dyspnea, and health-related quality of life) were measured at baseline and 24-week intervals. Validity and responsiveness were examined using Spearman correlation coefficients. The outcomes of the study indicate that 6MWD is a valid and effective clinical endpoint, which provides objective and clinically meaningful information regarding functional status and near-term prognosis of IPF patients.
References: 3
Study Validation 3
The study aimed to perform a systematic review of the validity, reliability and responsiveness of the 6MWT in cardiac rehabilitation. Studies using 6MWTs in subjects with coronary artery disease undergoing cardiac rehabilitation on an outpatient basis, published in English, were included. Quantitative and qualitative analyses were conducted, including quality assessment of methodology, meta-analysis and assessment against level of evidence criteria. Strong evidence suggests that the 6MWT is responsive to clinical change following cardiac rehabilitation.
References: 4
The 6-min walk test (6MWT) is cost-effective and well-documented field test for assessing functional exercise capacity and response to medical interventions in diverse patient groups, and predicting cardiorespiratory fitness among healthy people.This study aimed to develop a prediction model for VO2 max based on 6MWT results among healthy adults. The results of the study depicted that participant's mean walking distance was 652 m (SD ± 74). Their mean VO2 max in GXT and O2 uptake at the end of the 6MWT were 34·4 ml kg-1 min-1 (SD ± 7·6) and 27·2  ml kg-1 min-1 (SD ± 6·5), respectively
References: 5
Heart rate (HR) at the ventilatory threshold (VT) is often used to prescribe exercise intensity in cardiac rehabilitation. Some studies have reported no significant difference between HR at VT and HR measured at the end of a 6-min walk test (6-MWT) in cardiac patients. The aim of this study was to assess the potential equivalence between those parameters at the individual level. The study analysed 22 healthy elderlies (GES, 77 ± 3.7 years), 10 stable coronary artery disease (CAD) patients (GMI, 50.9 ± 4.2 years) and 30 patients with chronic heart failure (GHF, 63.3 ± 10 years). The results of the study indicated that 6-MWT-HR and VT-HR do not appear interchangeable at the individual level in healthy elderlies and CHF patients. In CAD patients, further larger studies and/or the development of other walk tests could help in confirming the interest of a training prescription based on walking performance, after an exhaustive study of their cardiometabolic requirements.
References: 6
Long-term heart rate (HR) control is a management strategy for patients with chronic atrial fibrillation (AF). Nevertheless, the optimal target HR of AF patients is debatable. The aim of the study was to evaluate HR at rest, during, and after a 6-minute walk test (6MWT) in AF patients, compared with controls with sinus rhythm (SR). Consecutive matched patients with AF (n = 186) or SR (n = 172) were recruited, and 6MWT was performed. HRs at rest, during 6MWT, and recovery periods were recorded. The study concluded that HR increased excessively during 6MWT and HR recovery was delayed after 6MWT in AF patients, especially when HR at rest is >90 beats/min.
References: 7

## Authors

Paul L. Enright
MD
Retired research professor of medicine, University of Arizona in Tucson
Research Interests: Pulmonary function testing, occupational lung disease, and diagnostic techniques for asthma and COPD
https://www.researchgate.net/profile/Paul_Enright
Duane Sherrill
Ph.D, 1989
Taught graduate courses in biostatistics and research in respiratory sciences , respiratory disease, mathematical modelling and statistics, Professor at University of Arizona in Tuscon