Six Minute Walk Test main image

Introduction

The six minute walk test (6MWT) is a widely used fixed time field test(FT) applied in various rehabilitation interventions, as an effective tool for analyzing functional capacity in patients with cardiovascular and pulmonary diseases(1). Functional capacity is the ability of a subject to carry out the routine activities or the activities of daily living (ADLs) such as bathing, dressing, or walking. The functional capacity is evaluated by cardiopulmonary exercise testing (CPET), which is a laboratory-based test and it requires special equipment and trained professionals. This necessitated the need for a simpler but similarly valid and reliable field test to measure functional capacity. The six minute walk test is used as an alternative to cardiopulmonary exercise testing as it is cost-effective, easy to perform, and is evaluated by the distance walked in six minutes at a self-selected pace.
Currently, the six minute walk test (6MWT) is well standardized by the American Thoracic Society/European Respiratory Society (ATS/ERS) and is the most often used test in clinical practice to determine the functional capacity of patients with chronic lung disease. Moreover, Six minute walk test is also a predictor of morbidity and mortality and may reflect the ability to perform activities of daily living in patients with chronic obstructive pulmonary disease (COPD)(2).

Purpose

The six minute walk test is used in clinical practice for exercise tolerance assessment, evaluation of eligibility for treatment and rehabilitation as well as the determination of their outcomes, and patient prognosis(3).

Participant Selection

The six minute walk test can be used in patients with cardiovascular and pulmonary diseases, before and after surgical interventions. It can also be used in neurological disorders, other chronic diseases, children, adults (sedentary, obese, middle-aged, and older-aged) as well as in healthy people.

Indications

The main indications are:
1) Assessment of treatment outcomes
2) Assessment of exercise tolerance
3) Determination of the patient prognosis

The indications of 6MWT based on the guidelines of the American Thoracic Society are:
Pre and post-treatment comparisons
Lung transplantation
Lung surgery (including lung resection, lung volume reduction)
Pulmonary rehabilitation
Chronic obstructive pulmonary disease (COPD)
Pulmonary hypertension
Cardiac insufficiency
Assessment of Functional capacity and exercise tolerance
Chronic obstructive pulmonary disease (COPD)
Cystic fibrosis
Cardiac insufficiency
Peripheral vascular diseases
Fibromyalgia
Elderly patients
Prediction of morbidity and mortality
Cardiac insufficiency
Chronic obstructive pulmonary disease (COPD)
Pulmonary hypertension

Contraindications

Absolute contraindications for the six minute walk test include the following:

  • Unstable angina (during the previous month)
  • Heart failure exacerbation
  • Myocardial infarction during the previous month
  • Primary angioplasty for STEMI within 7-10 days
  • Elective coronary angioplasty within 24 hours
  • Myocarditis or endocarditis
  • Symptomatic arrhythmia and/or conduction disorder
  • Acute deep vein thrombosis (DVT), pulmonary embolism, pulmonary infarction

Relative contraindications include:

  • Resting heart rate more than 120 bpm
  • Systolic blood pressure(SBP) more than 180mmHg or diastolic blood pressure(DBP) more than 100mmHg
  • Uncontrolled arterial hypertension

Six Minute Walk Test Procedure

Equipment Required:

  • A 30-meter straight uninterrupted pathway
  • Measuring tape/ measuring scale
  • Two cones to mark the starting and turnaround points
  • Stopwatch/ timer
  • Mechanical lap counter
  • Easily movable chair
  • Sphygmomanometer
  • Pulse oximeter
  • Borg scale (for breathlessness scoring)
  • Source of oxygen
  • Resuscitation equipment

Preparation Of The Pathway/ Location

  • The pathway to perform 6MWT should be 30 meters long, straight, uninterrupted
  • Marks has to be made at every 3-meter interval in order to facilitate the measurements
  • Two cones have to be placed at the starting and the turn around point
  • A chair should be placed at the halfway or two chairs can be placed at the starting and turn around point so that the patient can sit and rest during or after the test if needed.
  • Make sure there is easy access to oxygen and telephone in case of emergency

Preparation Of The Patient

  • Make sure that the patient is wearing comfortable clothing and shoes
  • If the patient is a regular user of any walking aid, then instruction has to be given to use the walking aid during the test
  • Any prescribed medications (like bronchodilators) should be taken before the test
  • If the patient is on supplemental oxygen, use a portable oxygen cylinder with the same oxygen level that he/she normally uses
  • Light meals can be taken before morning and afternoon tests
  • The patient should rest at least 10 minutes before the test and should not have done any vigorous exercise

Six Minute Walk Test Method

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Six minute walk test image
  • Make sure that the medical history and contraindications are reassessed
  • Record pre vitals- Blood pressure, heart rate, oxygen saturation(SpO2) and make sure the patient is stable
  • Make the patient stand and use the borg scale to rate his/her dyspnea and fatigue
  • Set the lap counter to zero and move to the starting point
  • Patient instructions and encouragement must be standardized (according to ATS).
  • Instruct the patient as follows: “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 am going to show you. Please watch the way I turn without hesitation”. Demonstrate by walking and instruct the patient to walk as far as possible in 6 minutes, not to run or jog. Clarify any questions from the patient.
  • Position yourself and the patient at the starting point. Start the timer as soon as the patient starts to walk.
  • Always note to walk behind the patient when you are accompanying him/her, to avoid influencing the walking pace of the patient
  • Use the following standard encouragements:
    • After the 1st minute, “You are doing well. You have 5 minutes to go”.
    • When 4 minutes left, “Keep up the good work. You have 4 minutes to go”.
    • When 3 minutes left, “You are doing well. You are halfway done”.
    • When 2 minutes left, “Keep up the good work. You have only 2 minutes left”.
    • When 1 minute left, “You are doing well. You have only 1 minute to go”.
    • When the timer is 15 seconds left for completion, “In a moment I am going to tell you to stop. When I do, just stop right where you are and I will come to you”.
    • At 6 minutes, “Please stop where you are”.
  • Once stopped, put a marker at the distance stopped and make the patient sit comfortably. If the patient prefers to stand, allow him/her to stand.
  • Immediately record post vitals – Blood pressure, heart rate, oxygen saturation(SpO2), and assess the rate of perceived exertion using the Borg scale.
  • Heart rate recovery (HRR) at each minute for 3 minutes (HRR1, HHR2, HHR3) can be recorded to assess for any abnormal HRR which is associated with morbidity and mortality of various respiratory diseases. [Note: This step is exceptional]
  • If the patient stops during the test to rest in between, keep the timer running.
  • If the patient stops the test, always ask the reason for the termination or what limited him/her to stop the test.
  • Record the total laps, and excess distance walked can be measured using a tape rounding to the nearest meter marked.
  • Congratulate the patient for the effort and monitor for any signs and symptoms.

Six Minute Walk Test Formula

The formula is used to predict the normal value for the six minute walk test(4).
Predicted 6MWD = 218 + [5.14 x height cm – 5.32 x age in years] – [1.80 x weight kg] + [51.31 x gender]
Gender is factored into the equation by male=1, female=0

For example, a male patient aged 65 years with a height of 159 cm and weighs 38 kg completed 5 laps in six minute walk test.
Calculation to predict the normal value of the distance he should walk:
6MWD = 218 + [5.14 x height cm – 5.32 x age in years] – [1.80 x weight kg] + [51.31 x gender]
= 218 + [5.14 x 159 – 5.32 x 65] – [1.80 x 38] + [51.31 x 1]
= 218 + [471.46] – 68.4 +51.31
= 672.37 m
Hence the predicted 6MWT normal value is 672.37m. But the patient completed 5 laps which is 300 m.

Interpretation

According to studies, the distance walked by a healthy subject on six minute walk test ranges from 400 to 700 meters. Reference values for the average distance in a group of healthy men and a group of healthy women ranged from 735 meters (±98 meters) to 580 meters and from 657 meters (± 56 meters) to 500 meters respectively. If the distance walked in 6MWT is near to normal predicted value, it indicates a good functional capacity. An increase of more than 60 meters in the subsequent tests is considered a significant improvement in terms of rehabilitation outcomes.

Six Minute Walk Test In Physical Therapy

six minute walk test used in cardiac and pulmonary rehabilitation as well as in patients with neurological disorders to assess the exercise tolerance and prognosis of a patient.

Check Our YouTube Video Of Six Minute Walk Test

References

  1. J.Papathanasiou, Y.Dionyssiotis, P.Kasnakova et al. Six-minute walk test: A tool for assessing mobility in frail subjects. J Frailty, Sarcopenia Falls. 2016;01(04):73–6.
  2. Labadessa IG, Arcuri JF, Sentanin AC, da Costa JNF, Pessoa B V., Di Lorenzo VAP. Should the 6-minute walk test be compared when conducted by 2 different assessors in subjects with COPD? Respiratory Care. 2016;61(10):1323–30.
  3. Machała E, Zadworny D, Janiak J, Machała P. Application of six minute walk test in clinical practice. world Sci news. 2018;107(August):125–35.
  4. Dourado VZ. [Reference Equations for the 6-Minute Walk Test in Healthy Individuals.]. Arq Bras Cardiol [Internet]. 2011; Available from: http://www.ncbi.nlm.nih.gov/pubmed/21359481
  5. Issues S, Test MW, Equipment R, Preparation P. American Thoracic Society ATS Statement: Guidelines for the Six-Minute Walk Test. Am J Respir Crit Care Med. 2002;166:111–7.

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