Six-Minute Walk Test
Standardisation of the six-minute walk test (6MWT) is very important.
At the commencement of pulmonary rehabilitation, the 6MWT must be performed on two occasions 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 individuals 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 25m track, make sure you use the same track for all tests and be aware that 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.
- 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 identified in the attached checklist.
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 two hours 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.
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.
Before the Test
Describe the walking track to the patient and then give the patient the following instructions:
“You are now going to do a six-minute walking test. The object of this test is to walk as quickly as you can for six minutes (around the track; up and down the corridor etc… depending on your track set up) so that you cover as much ground as possible.
You may slow down if necessary. If you stop, I want you to continue to walk again as soon as possible. You will be regularly informed of the time and you will be encouraged to do your best. Your goal is to walk as far as possible in six minutes.
Please do not talk during the test unless you have a problem or I ask you a question. You must let me know if you have any chest pain or dizziness.
When the six minutes is up I will ask you to stop where you are. Do you have any questions?”
Begin the test by instructing the patient to:
“Start walking now.”
During the Test
Monitor the patient for untoward signs and symptoms.
Use the following standard encouragements during the test:
o At minute one:
“Five minutes remaining (patient name). Do your best!”
o At minute two:
“Four minutes remaining (patient name). You’re doing well – keep it up!”
o At minute three:
“Half way – three minutes remaining (patient name). Do your best!”
o At minute four:
“Two minutes remaining (patient name). You’re doing well – keep it up!”
o At minute five:
“One minute remaining (patient name). Do your best!”
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.
Note: The measurements taken before and after the test should be taken with the patient in the same position.
- Immediately record oxygen saturation (SpO2)%, heart rate and dyspnoea rating on the 6MWT recording sheet.
- 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.
Normally the clinician does not walk with the patient during the test to avoid the problem of setting the walking pace. The pulse oximeter should be applied immediately if the patient chooses to rest, and at completion of the six-minute walking period. Any delay may result in readings being recorded that are not representative of maximum exercise response.
In some instances, the clinician may choose to walk with the patient for the entire test (e.g. if continuous oximetry is desired). If this is the case the clinician should try to walk slightly behind the patient to avoid setting the walking pace. Alternatively, if the oximeter is small and lightweight, it may be attached to the patient and checked throughout the test without interfering with 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).
- Give the following encouragement (repeat this encouragement every 15 seconds if necessary):“Begin walking as soon as you feel able.”
- 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 < 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 2009].
- 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).
6MWT as an Outcome Measure
The change in the distance walked in the 6MWT can be used to evaluate the efficacy of an exercise training program or 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 has traditionally been estimated as 54 metres (with 95% confidence limits of 37 to 71 metres) [Redelmeier, 1997]. More recently a distance of 35 metres (95% confidence limits 30 to 42 metres) was identified as representing an important effect in COPD, although this distance did not appear to be important to patients [Puhan 2008]. In interstitial lung disease, an MID of 31 metres (95% confidence limits 19 to 45 metres) has been identified [Holland 2009].
Smaller improvements in 6MWT distance may occur in patients who walk a very short distance (eg less than 200 metres) in their 6MWT before pulmonary rehabilitation. For these patients, it may be more reasonable to evaluate efficacy based on the percent change rather than a change in a set number of metres. A change of 10% has been suggested as clinically important in COPD [Puhan 2008].