The Six-Minute Walk Test (6MWT)
Standardisation of the six-minute walk test (6MWT) is very important.
At the commencement of PR, the 6MWT must be performed twice to account for a learning effect. Please note that:
- The best distance walked in metres is recorded.
- If the two tests are performed on the same day, at least 30 minutes rest should be allowed between tests. Debilitated patients may require tests to be performed on separate days, preferably less than one week apart.
- The walking track should be the same layout for all tests for a patient:
- The track may be a continuous track (oval or rectangular) or a point-to-point (stop, turn around, go) track.
- The track should be flat, with minimal blind turns or obstacles.
- The minimum recommended length for a centre-based walking track is 25m and could be marked in metre increments.
Note: If you do not have access to a track of at least 25m, make sure you use the same track for all tests and be aware that with a shorter track the distance walked may be less due to the patient having to slow down and turn more often in the six minutes.
- A comfortable ambient temperature and humidity should be maintained for all tests.
These standard instructions apply for all respiratory conditions.
The information from the 6MWT can be used to prescribe the intensity of walking exercise (see Exercise Training section).
The equipment needed to conduct the 6MWT is outlined below:
- At least one chair, positioned at one end of the walking course
- A dyspnoea scale and a fatigue scale
- Sphygmomanometer for blood pressure measurement
- Pulse oximeter (Forehead probes are recommended for patients with Pulmonary Hypertension)
- Pre-measured marks each meter along the track/corridor
- Access to oxygen and telephone in case of an emergency
- An emergency plan
- Portable supplemental oxygen if required by patient to perform exercise test
- Clipboard with reporting sheet and pen
Before the 6MWT
- Ensure that you have already obtained a medical history for the patient and have taken into account any precautions or contraindications to exercise testing.
- Instruct the patient to dress comfortably, wear appropriate footwear and to avoid eating for at least one hour before the test (where possible or appropriate).
- Any prescribed inhaled bronchodilator medication should be taken within one hour of testing or when the patient arrives for testing.
- The patient should rest for at least 15 minutes before beginning the 6MWT.
- Blood pressure.
- Heart rate.
- Oxygen saturation.
- Dyspnoea score.*
* Note: Show the patient the dyspnoea scale (i.e. Borg scale) and give standardised instructions on how to obtain a score.
- If a patient is on inhaled vasodilator therapy this should be administered 30 minutes prior to the exercise test.
- In PAH pre -test screening should also include assessment of recent illness, syncope, evidence of RHF, chest pain and any increase in breathlessness.
Instructions for the 6MWT
Instructions and encouragement must be standardised.
Tip: Put the instructions on a laminated card and read them out to each patient. See below italics.
Before the Test
The oximeter is to be attached to the patient so it is ready to be checked throughout the test without interfering with walking pace.
Describe the walking track to the patient and then give the patient the following instructions6:
The aim of this test is to walk as far as possible for 6 minutes. You will walk along this hallway between the markers, as many times as you can in 6 minutes.
I will let you know as each minute goes past, and then at 6 minutes I will ask you to stop where you are.
6 minutes is a long time to walk, so you will be exerting yourself. You are permitted to slow down, to stop, and to rest as necessary, but please resume walking as soon as you are able.
Remember that the objective is to walk AS FAR AS POSSIBLE for 6 minutes, but don’t run or jog.
Do you have any questions?
During the Test
Monitor the patient for untoward signs and symptoms.
Use the following standard encouragements during the test6:
- 1 min “You are doing well. You have 5 minutes to go.”
- 2 min “Keep up the good work. You have 4 minutes to go.”
- 3 min “You are doing well. You are halfway.”
- 4 min “Keep up the good work. You have only 2 minutes left.”
- 5 min “You are doing well. You have only 1 minute to go.”
- 6 min “Please stop where you are.”
If the patient stops during the test, every 15 s if SpO2 is >85% “Please resume walking whenever you feel able.”
Continuous monitoring of SpO2 and HR should be performed during the test and results recorded each minute. If the Nadir (lowest) SpO2 is observed at a different time-point then this should also be recorded as it is an important prognostic indicator
At the End of the 6MWT
- Put a marker on the distance walked.
- Seat the patient or, if the patient prefers, allow to the patient to stand.
- Immediately record oxygen saturation (SpO2)%, heart rate and dyspnoea rating on the 6MWT recording sheet.
- It is important to understand the reason for test termination/limitation, so patients should be asked why they could not walk any further if they had to stop during the test.
- Measure the excess distance with a tape measure and tally up the total distance.
The patient should remain in a clinical area for at least 15 minutes following an uncomplicated test.
The pulse oximeter should be worn continuously and levels to be recorded at every minute. Normally the clinician does not walk with the patient during the test to avoid the problem of setting the walking pace.
In some instances, the clinician may choose to walk with the patient for the entire test. If this is the case the clinician should try to walk slightly behind the patient to avoid setting the walking pace.
If the Patient Stops During the Six Minutes
- Allow the patient to sit in a chair if they wish.
- Measure the SpO2% and heart rate.
- Ask patient why they stopped.
- Record the time the patient stopped (but keep the stop watch running).
- Once SpO2% >= 85% give the following encouragement (repeat this encouragement every 15 seconds if necessary).6 “Begin walking as soon as you feel able.”
- Monitor the patient for untoward signs and symptoms.
- Monitor the patient for untoward signs and symptoms.
Stop the Test in the Event of Any of the Following
- Chest pain suspicious for angina.
- Evolving mental confusion or lack of coordination.
- Evolving light-headedness.
- Intolerable dyspnoea.
- Leg cramps or extreme leg muscle fatigue.
- Persistent SpO2 < 80%. (In a community setting the test may be stopped if SpO2 < 85%)
- Any other clinically warranted reason.
Predicted Normal Values for the 6MWT
The following predictive equations use the reference values determined from a study that performed two 6MWTs according to the above protocol [For further details, see Jenkins, et al., 20097]
- Predictive equation for males: 6MWD(m) = 867 – (5.71 age, yrs) + (1.03 height, cm)
- Predictive equation for females: 6MWD(m) = 525 – (2.86 age, yrs) + (2.71 height, cm) – (6.22 BMI).
- Reference equations generated and verified in a local population should be applied where possible. A summary of reference equations can be found in Singh , S. J. et al., 2014. An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease. European Respiratory Journal, December, 44(6), pp. 1447-1478.5
6MWT as an Outcome Measure
The change in the distance walked in the 6MWT: 1) after completion of a pulmonary rehabilitation program can be used to evaluate the effectiveness of the exercise training program; 2)may be used to trace the natural history of change in exercise capacity over time.
The minimum important difference (i.e. improvement) in the distance walked in a 6MWT is 30 metres (95% confidence limits 25 to 33 metres).6