Six Minute Walk Test / 6 Minute Walk Test

 

Objective

Blender3D NormalWalkCycle.gif

The six minute walking test (6MWT) was developed by the American Thoracic Society and it was officially introduced in 2002, coming along with a comprehensive guidelines[1].

The 6 Minute Walk Test is a sub-maximal exercise test used to assess aerobic capacity and endurance. The distance covered over a time of 6 minutes is used as the outcome by which to compare changes in performance capacity.



Intended Population

The 6MWT can be used in preschool children (2-5 years), children (6-12 years) adults (18-64 years), elderly adults (65+) with a wide range of diagnoses including. The test was initially designed to help in the assessment of patient with cardiopulmonary issues. Gradually, it was introduced in numerous other conditions. It evaluates the functional capacity of the individual and it provides valuable information regarding all the systems during physical activity, including pulmonary and cardiovascular systems, blood circulation, neuromuscular units, body metabolism, and peripheral circulation[1].

Some conditions where 6MWT can be used are listed below:

Method of Use

[2]

Equipment Required:

  • Stopwatch
  • Measuring/trundle wheel to measure distance covered
  • 30-metre stretch of unimpeded walkway
  • Two cones to mark the distance that needs to be covered
  • Pulse oximeter for measuring heart rate and SpO2 (optional)
  • Borg Breathlessness Scale (optional)

Set-Up:

  • Place cones at either end of the 30 metre stretch as turning points
  • Have chairs set up either side and halfway along the walking stretch

Patient Instructions:

  • "The object of this test is to walk as far as possible for 6 minutes. You will walk back and forth in this hallway. Six minutes is a long time to walk, so you will be exerting yourself. You will probably get out of
    breath or become exhausted. You are permitted to slow down, to stop, and to rest as necessary. You
    may lean against the wall while resting, but resume walking as soon as you are able. You will be walking
    back and forth around the cones. You should pivot briskly around the cones and continue back the other
    way without hesitation. Now I’m going to show you. Please watch the way I turn without hesitation.”
[3]
  • Read this standardised encouragement during the test: 
  • After the 1st minute: “You are doing well. You have 5 minutes to go.”
    When the timer shows 4 minutes remaining: “Keep up the good work. You have 4 minutes to go.”
    When the timer shows 3 minutes remaining: “You are doing well. You are halfway done.
    When the timer shows 2 minutes remaining: “Keep up the good work. You have only 2 minutes left.
    When the timer shows 1 minute remaining: “You are doing well. You only have 1 minute to go.
    With 15 seconds to go: “In a moment I’m going to tell you to stop. When I do, just stop right where you
    are and I will come to you.”
    At 6 minutes: “Stop”
  • If the participant stops at any time prior, you can say: “You can lean against the wall if you would like; then continue walking whenever you feel able.”
  • Do not use other words of encouragement (or body language) to influence the patient’s walking speed. Accompany the participant along the walking course, but keep just behind them. Do not lead
    them.
  • If available record the distance at which the oxygen saturation drops < 88%

Interpretation

An increase in the distance walked indicates improvement in basic mobility. Resnik et al (2011)[4] suggested in Amputee rehabilitation, Post training a difference of at least 45m should be observed for the 6 minutes walk test to be sure that a “real” change in the patient’s condition.

In some neuromuscular conditions such as Duchenne/Becker muscular dystrophy, Spinal Muscular Atrophy, Charcot-Marie-Tooth disease, and Myasthenia Gravis the 6MWT has been implemented in the assessment of those patients and it has been regularly used to capture any changes, which provides valuable information regarding the natural history of these disorders.

Some studies used the six minute walking test to identify patients with neuromuscular junction dysfunction[5]. By splitting the test into six different components where each minute is a different data point, the researches discovered that the 6MWT can identify any malfunctions in the neuromuscular junctions. Also by comparing the distance covered in the first and the last minute suggested how much the fatigue has influenced the individual.

Evidence

Reliability

Test-Retest Reliability

Alzheimer’s Disease:
(Ries et al, 2009, Alzheimer’s disease)

  • Excellent test-retest reliability for all participants (ICC = 0.98) [6]

Geriatrics:
(Harada et al, 1999; n = 86; mean age = 75 (6) years, Geriatrics)

  • Excellent test-retest reliability (r = 0.95) [7]

(Steffen et al, 2002, Geriatrics)

  • Excellent test-retest reliability (ICC = 0.95) [8]

Osteoarthritis:
(Kennedy et al, 2005, Osteoarthritis)

  • Excellent test-retest reliability (ICC = 0.94) [9]

Stroke:
(Eng et al, 2004; n = 12 community-dwelling individuals who had a stroke with moderate motor deficits; mean time since stroke onset = 3.5 (2.0) years; mean age = 62.5 (8.6) years, Chronic Stroke) [10]

  • Excellent test-retest reliability (ICC = 0.99 distance in meters)
  • Excellent test-retest reliability for VO2 (ICC = 0.99)

(Flansbjer et al, 2005, Chronic Stroke) [11]

  • Excellent Test-retest reliability (ICC = 0.99)

(Fulk et al, 2008; n = 35 patients who are enrolled in inpatient rehabilitation after stroke; mean age = 67.4 (13.8) years; mean time since stroke onset = 34.5 (17.7) days, Acute Stroke) [12]

  • Excellent test-retest reliability for all participants (ICC = 0.862)
  • Excellent test-retest reliability for those who require physical assistance to walk (ICC = 0.97)
  • Excellent test-retest reliability for those who can walk without assistance (ICC = 0.80)
  • Excellent test-retest reliability for those require an assistive device to walk (ICC = 0.914)

(Wevers et al, 2011, Chronic Stroke) [13]

  • Excellent test-retest reliability between first and second 6MWTs outdoors (ICC = 0.96 for GPS and 0.98 for measuring wheel)

TBI:
(Mossberg, 2003, n = 23; mean age 35.5 (12.5) years male, 30.5 (12.8) years female; approximately 12 months since injury, TBI) [14]

  • Excellent test re-test reliability (ICC = 0.94)

(VanLoo et al, 2004, n = 13; mean age = 32.5 (11.3) years; average time post injury 11.9 (15.7) months; mean initial GCS 5.8 (2.9); mean PTA 43.8 (39.1) days, TBI) [15]

  • Excellent test re-test reliability (ICC = 0.96)

Parkinson's Disease:
(Steffen et al, 2008) [16]

  • Excellent test retest reliability (ICC = 0.95 - 0.96)

Interrater/Intrarater Reliability

Alzheimer’s Disease:
(Tappen et al. 1997; n = 33; mean age = 84.7 (3.94) years, Alzheimer’s Disease) [17]

  • Excellent interrater reliability (ICC = 0.97 - 0.99)
  • Excellent intrarater reliability (ICC = 0.76 - 0.9)

SCI:
(Scivoletto et al, 2011; n = 37; median age = 58.5 (range 19–77) years; median time from onset = 24 (range 6–109) months; AIS D = 35, C = 2; Median; WISCI = 16, Chronic SCI) [18]

  • Excellent Inter-rater reliability (ICC = 0.99)
  • Excellent Intra-rater reliability (ICC = 0.99)

(van Hedel et al, 2005; n = 22; AIS-A = 1, B = 0, C = 3, D = 18; mean age = 52 (20) years) [19]
Tested on 3 occasions within 7 days:

  • Excellent inter-rater reliability (r = 0.97)

Determined by comparing the 2 measurements performed by a single therapist

  • Excellent intra-rater reliability (r = 0.98)
  • Bland Altman plot: Inter-rater reliability > intra-rater reliability and may indicate first test influence over second test

Stroke:
(Kosak & Smith, 2005; n = 18; mean age = 77 (11) years; mean time since stroke onset = 28 (34) day; enrolled in inpatient rehabilitation; mean FIM score at time of admission to inpatient rehabilitation = 68 (17), Acute Stroke) 

  • Adequate Intra-rater reliability (ICC = 0.74)
  • Adequate Inter-rater reliability (ICC = 0.78)

Validity

Criterion Validity

COPD:
(Szekely et al, 1997; n = 47, average age 60.5 (7.5) years, individuals undergoing volume reduction surgery, COPD) [20]

  • Inability to walk > 200m before the operation and resting PzCO2 > 45 were the best predictors of unacceptable postoperative outcome and mortality (specificity = 84%, sensitivity = 82%)
  • Adequate correlation with length of hospital stay:
  • Pre-surgical 6MWT (R = 0.32)
  • Post-surgical 6MWT (R = 0.40)

Elderly:
(Harada et al, 1999; n = 86 older adults without significant disease; 35 were recruited from retirement homes and 57 from community centers; mean age = 75 (6) years, Elderly) [21]

  • Adequate concurrent validity with:
  •   Chair stands (r = 0.67)
  •   Standing balance (r = 0.52)
  •   Gait speed (r = -0.73)
  •   *Distance walked was greater in active older healthy adults than in inactive older healthy adults (p < 0.0001)

SCI:
(Lam et al, 2008, SCI) [22]

  • Excellent concurrent validity with: 10 Meter Walk Test (r = -0.95)
  •   Adequate concurrent validity with: Timed Up and Go (r = -0.88)
  •   Poor concurrent validity with Walking Index for SCI II (r = 0.60)

Stroke:
(Flansbjer et al, 2005, Chronic Stroke) [23]

  • Excellent concurrent validity with:
  •   TUG (r = -0.89)
  •   10  meter comfortable gait speed (r = 0.84)
  •   10 meter fast gait speed (r = 0.94)
  •   Stair Climbing Ascend (r = -0.82)
  •   Stair Climbing Descend (r = -0.80)

Construct Validity

Geriatrics:
(Harada et al, 1999, Geriatrics) [7]

  • Adequate correlation with chair stands (r = 0.67), tandem balance (r = 0.52), and gait speed (r = -0.73)
  • Adequate correlation with SF 36 physical function subscale (r = 0.55) and general health perceptions subscale (r = 0.39)
  • Poor correlation with BMI (r = -0.07)

SCI:
(van Hedel et al, 2007; longitudinal study looking at 6min and 10 MWT at 1, 3, and 6 mo post injury, incomplete SCI who were able to ambulate 10m within 3 months post SCI n = 51, 22 tetraplegic, 29 paraplegic. Cross sectional study n = 18 incomplete SCI, acute and chronic range 2wks to 8 years AIS-C or D, utilized middle 10m of 14m walk, Acute/Subacute SCI) [19]

  • Walking speed differed at each time period (1, 3, 6 mo post) but did not differ between the tests
  • Regression analysis performed to look at relationship between the tests at preferred and maximum walking speed
    Preferred walking speed R2 = 0.87
    Maximum walking speed R2 = 0.86

Responsiveness

COPD:
(Casanova et al, 2007, COPD) [24]

  • Demonstrates significant decline in those individuals with severe airflow limitation (FEV1 < 50%)
  • Decline worsened with disease severity

Geriatrics:
(Perera et al, 2006, Geriatrics) [25]

  • Small meaningful change 20 m
  • Substantial meaningful change 50 m

SCI:
(van Hedel et al, 2006, SCI) 

  • For individuals with incomplete SCI, the 6MWT was able to detect walking capacity improvements in patients with less ambulatory impairment during the acute and subacute stages of recovery at 3 and 6 months post injury. Similar findings were not demonstrated with the WISCI II or LEMS.
  • Statistically significant responsiveness 1-3 months post injury and 3-6 months post injury with larger effect size noted 1-3 months post injury (found in Lam et al, 2008)
  • For individuals with incomplete SCI, the 6MWT was not able to detect walking capacity improvements between 6 and 12 months post injury.
  •   May be a result of this sample having reached normal walking speeds at 6 months post injury (1.39 m/s)

Further study with a larger sample size needs evaluate responsiveness for chronic (> 12 months ) injuries

Stroke:
(Kosak & Smith, 2005, Stroke) 

  • Over a 3.9 (2) week inpatient rehabilitation stay SRM = 1.52

Miscellaneous

Links

6 Minute Walk Test

Recent Related Research (from Pubmed)

References

  1. 1.0 1.1 Laboratories, A. T. S. C. o. P. S. f. C. P. F. (2002). "ATS statement: guidelines for the six-minute walk test." Am J Respir Crit Care Med 166(1): 111-117.
  2. gonetilnovembr19. 6 Minute Walk Test Instructional Video. Available from: http://www.youtube.com/watch?v=6EXNes7mO1o[last accessed 10/10/14]
  3. YSUMediaAcademicComp. Six Minute Walk Test 2012. Available from: http://www.youtube.com/watch?v=JHzsgeudQ1I[last accessed 10/10/14]
  4. Resnik, L. and Borgia, M., (2011). Reliability of outcome measures for people with lower-limbfckLRamputations: distinguishing true change from statistical error. Physical Therapy, 91(4), pp. 555-565.
  5. Pera, M. C., et al. (2017). "6MWT can identify type 3 SMA patients with neuromuscular junction dysfunction." Neuromuscul Disord 27(10): 879-882.
  6. Ries, J. D., Echternach, J. L., et al. "Test-retest reliability and minimal detectable change scores for the timed "up & go" test, the six-minute walk test, and gait speed in people with Alzheimer disease." Phys Ther 2009 89(6): 569-579
  7. 7.0 7.1 Harada, N., Chiu, V., et al. "Mobility-related function in older adults: assessment with a 6-minute walk test." Archives of physical medicine and rehabilitation 1999 80(7): 837-841
  8. Steffen, T. M., Hacker, T. A., et al. "Age- and gender-related test performance in community-dwelling elderly people: Six-Minute Walk Test, Berg Balance Scale, Timed Up & Go Test, and gait speeds." Physical Therapy 2002 82(2): 128-137
  9. Kennedy, D. M., Stratford, P. W., et al. "Assessing stability and change of four performance measures: a longitudinal study evaluating outcome following total hip and knee arthroplasty." BMC Musculoskelet Disord 2005 6: 3
  10. Eng, J. J., Dawson, A. S., et al. "Submaximal exercise in persons with stroke: test-retest reliability and concurrent validity with maximal oxygen consumption." Arch Phys Med Rehabil 2004 85(1): 113-118
  11. Flansbjer, U. B., Holmback, A. M., et al. "Reliability of gait performance tests in men and women with hemiparesis after stroke." J Rehabil Med 2005 37(2): 75-82
  12. Fulk, G. D. and Echternach, J. L. "Test-retest reliability and minimal detectable change of gait speed in individuals undergoing rehabilitation after stroke." J Neurol Phys Ther 2008 32(1): 8-13
  13. Wevers, L. E., Kwakkel, G., et al. "Is outdoor use of the six-minute walk test with a global positioning system in stroke patients' own neighbourhoods reproducible and valid?" J Rehabil Med 2011 43(11): 1027-1031
  14. Mossberg, K. A. "Reliability of a timed walk test in persons with acquired brain injury." Am J Phys Med Rehabil 2003 82(5): 385-390; quiz 391-382
  15. van Loo, M. A., Moseley, A. M., et al. "Test-re-test reliability of walking speed, step length and step width measurement after traumatic brain injury: a pilot study." Brain Inj 2004 18(10): 1041-1048
  16. Steffen, T. and Seney, M. "Test-retest reliability and minimal detectable change on balance and ambulation tests, the 36-item short-form health survey, and the unified Parkinson disease rating scale in people with parkinsonism." Physical Therapy 2008 88(6): 733-746
  17. Tappen, R. M., Roach, K. E., et al. "Reliability of physical performance measures in nursing home residents with Alzheimer's disease." J Gerontol A Biol Sci Med Sci 1997 52(1): M52-55
  18. Scivoletto, G., Tamburella, F., et al. "Validity and reliability of the 10-m walk test and the 6-min walk test in spinal cord injury patients." Spinal Cord 2011 49(6): 736-740
  19. 19.0 19.1 van Hedel, H. J., Wirz, M., et al. "Assessing walking ability in subjects with spinal cord injury: validity and reliability of 3 walking tests." Archives of Physical Medicine and Rehabilitation 2005 86(2): 190-196
  20. Szekely, L., Oelberg, D., et al. "Preoperative predictors of operative morbidity and mortality in COPD patients undergoing bilateral lung volume reduction surgery." Chest 1997 111(3): 550
  21. Harada, N., Chiu, V., et al. "Mobility-related function in older adults: assessment with a 6-minute walk test." Archives of physical medicine and rehabilitation 1999 80(7): 837-841
  22. Lam, T., Noonan, V., et al. "A systematic review of functional ambulation outcome measures in spinal cord injury." Spinal Cord 2007 46(4): 246-254
  23. Flansbjer, U. B., Holmback, A. M., et al. "Reliability of gait performance tests in men and women with hemiparesis after stroke." J Rehabil Med 2005 37(2): 75-82
  24. Casanova, C., Cote, C. G., et al. "The 6-min walking distance: long-term follow up in patients with COPD." Eur Respir J 2007 29(3): 535-540
  25. Perera, S., Mody, S., et al. "Meaningful change and responsiveness in common physical performance measures in older adults." Journal of the American Geriatrics Society 2006 54(5): 743-749