6 Minute Walk Test Calculator

The six-minute walk test is a method of measuring the distance covered on level ground in six minutes. It is often used to assess functional capacity cost-effectively and simply, and to monitor the status of patients with heart or lung disease and their response to treatment.

This calculator will determine the expected walking distance in a six-minute walk test and the normal range for healthy adults of the same sex, age, height and weight. After entering the actual distance walked, it also displays the percentage compared to the predicted value.

What is a 6-minute walk test?

The six-minute walk test is an exercise test of submaximal intensity, in which the subject walks at his or her own pace for a set period of time (6 minutes), with the ability to slow down or rest if needed. It reflects activities of daily living rather than maximal exertion.

It is simple to perform and inexpensive, can be easily standardized, and causes little burden on patients; therefore it is suitable for elderly people and those with limited physical capacity. The distance covered in the 6-minute walk test (6MWD) is reduced in chronic obstructive pulmonary disease, heart failure, arthritis, and neuromuscular diseases. Therefore, it is helpful to evaluate the functional status and prognosis over time.

Calculation equation for the predicted walking distance.

Even in healthy individuals, there is a wide range of individual differences in walking distance so that simple measurement alone is not sufficient for comprehensive evaluation. In 1998 Enright and Sherrill developed a study with healthy men (117 subjects) and healthy women (173 subjects) aged 40 to 80 years old to create gender-specific formulas to predict the walking distance in adults. The median walking distance was 576 m for males and 494 m for females.

The predicted six-minute walk distance for men is calculated using this formula:

For women, use this formula:

In this formula H is the height of a person in centimeters, A is their age and W is their weight in kilograms. The result will be given in meters. The calculator first converts the units you input to those required by the formula before performing the calculation.

Normal range

A single predicted value cannot fully reflect the natural variability within a healthy population, so for each formula there are normal range limits. For men, the predicted values are reduced by 153m and for women it is 139m.

If the actual measured walking distance is above the normal lower limit it is within the expected range. If it is below this then this indicates reduced ability to walk and a more detailed assessment may be required. However, it is important not just to judge on the basis of the distance but always consider the whole clinical picture.

Example calculation:

Let's take a man aged 72 with a height of 177 cm and a weight of 80 kg. If these values are put into the formula for men, this is what results:

The normal lower limit is about 376 meters, calculated from the difference between 529 and 153. Assuming that the actual distance traveled was 432 meters. This value is above the normal lower limit. In addition, the percentage relative to the predicted value is as follows:

This patient has a walking distance of about 82 percent compared to the predicted distance for a healthy man of the same age, with the same height and weight, which means that the result is within the normal range.

Interpretation of percentage relative to predicted value:

Using percentages relative to predicted values allows the actual measured distances to be plotted on a common scale which makes it easier to compare changes over time in the same person or between people of different body sizes. An increase in percentage after treatment or rehabilitation is a good sign. A decrease may indicate dysfunction that should be investigated further.

In clinical practice, the actual distance walked is most important. For many chronic conditions a change of about 25 to 35 meters between tests is considered meaningful for an individual patient. The exact criteria depend on the particular disease.

Important notes before the examination:

The six-minute walk test is safe for many people but not everyone. It should not be done within a month of having a heart attack or with unstable angina.

Relative contraindications include a resting heart rate over 120, systolic blood pressure over 180 or diastolic blood pressure over 100. If chest pain, intolerable shortness of breath, leg cramps, dizziness, profuse sweating, or pallor occur, walking should be stopped immediately. A fully standardized protocol is described in the American Thoracic Society guidelines.

Symbols used:

This calculator is for general educational purposes only. It estimates a reference distance but cannot provide diagnosis. The Six Minute Walk Test should be performed and interpreted by qualified medical personnel, along with other assessments.