Norm values six-minute walktest for Dutch children.

The 6 minute walk test (6MWT ) is a widely used test for measuring sub-maximal
exercise capacity, i.e. the functional exercise capacity needed in everyday
life.The 6 MWT measures the distance that the participant can quickly walk on a
flat hard surface in a period of 6 minutes. The test is self-paced. The 6MWT
was originally developed to measure the submaximal level of functional capacity
in adult patients. The American Thoracic Society (ATS) has published guidelines
for performing the 6 MWT with adults in a clinical setting. Nowadays the 6MWT
is used regularly in pediatric populations as well, for example children with
mucopolysaccharidosis, Duchenne muscular dystrophy, spina bifida and children
with malignancies. It is found to be a useful test for children who are
moderately or severely impaired. A number of studies have produced reference
values for children. Two of the studies involved a European cohort. In one of
these the age span is too small. The other European study by Geiger et al
investigated 528 healthy Austrian children. However, in this study the 6MWT was
modified: to overcome lack of motivation children were provided with a
measuring wheel with an instantaneous display of the walking distance. The
reference values published by Geiger et al are therefore not applicable when
the 6MWT is performed according to the ATS guidelines. In addition, living
circumstances in Austria are different in terms of altiitude and also in the
fact that a large part of the population does not live in urban areas.

Primary objective:
To determine reference values for the 6-Minute Walk Test for Dutch healthy
children, when the test is performed according to the ATS guidelines.

The study has a cross-sectional observational design.

Sample size:
The study aims to establish norm values for the 6MWT for the Dutch population.
We propose additional testing of 20 boys and 20 girls aged 4 years en 20 boys
and 20 girls aged 5 years resulting in 2 x 40 children. In comparison to the
Geiger et al study the sample will be as below.
Male 4-5 years Geiger et al n=22; current study n=40
Female 4-5 years Geiger et al n=25; current study n=40


Investigated test:
The 6 minute walk test (6MWT) will be investigated. This test is designed to
measure sub-maximal functional exercise capacity, i.e. the exercise capacity
needed in everyday life. During the 6MWT children are requested to cover a
distance of 20 meters (marked by 2 pylons) as often as possible, for a period
of six minutes. Running is not permitted. The test is self-paced. Standardised
verbal instruction and encouragement i.e. *you rare doing well, carry on* and
*one minute has passed, another five minutes to go* as specified in the
guidelines of the American Thoracic Society, will be used.

Consent:
Informed consent will be obtained from parents. Parents who give consent will
be asked to fill out a short questionnaire regarding their child*s state of
health and level of physical activity. This will take parents approximately
5-10 minutes.

Test procedure:
The test will be conducted at school, during school hours. Children will be
requested to wear light clothes and shoes or trainers. Children will be
instructed not to exercise 2 hours prior to the test. Parents will be requested
to be present during the test procedure.The child will be collected during the
PE classes by the parent. Weight will be measured with an electronic scale
(Beurer PS-16 , Beurer, Ulm Germany). Height will be measured with a
stadiometer (Seca 206, Seca , Hamburg, Germany). Heart rate and oxygen
saturation will be measured with a finger pulse oximeter (Beijing Choice
Electronic Technology Co. Ltd, Beijing, China), at the start and on completion
of the test.This is not painful or uncomfortable.
The 6 MWT will be explained an demonstrated by the investigator. The child will
then perform the 6MWT. During the test only standardised encouragements, as
described in the ATS guidelines, are given. Each minute the child will be
informed how many minutes have passed and how many minutes of the test remain.
The number of times the complete distance between the pylons is covered is
recorded. The additional distance past the last pylon is measured with a tape
measure.

Duration:
The complete testing procedure will take approximately 15 minutes per child.

Recruitment:
In order to recruit healthy Dutch children primary schools reflecting those of
the general popualtion will be contacted. The principals of the school will be
approached with a letter, followed by personal contact. If the school is
willing to participate, parents will receive a letter explaining the purpose
and procedure of the study. They will be asked to make their decision know by
filling out the consent form. The will be given 14 days to make their decision
known. Parents who give their consent will receive a short questionnaire about
their child*s state of health, his or her regular physical activities and
amount of exercise.

Benefits and burden:
The 6 minute walk test (6MWT) is a useful tool as it measures sub-maximal
functional exercise capacity, i.e. the exercise capacity needed in everyday
life to participate in physical activities with peers. At present there are no
norm values for Dutch children. Reference values from a pediatric Caucasian
cohort from Austria are used in which the test procedure was modified. New norm
values therefore need to be determined for the Dutch pediatric population.

The burden of the test is considered to be minimal. Measurement of heart rate
and oxygen saturation takes place with a finger clip and is neither painful nor
uncomfortable. The instructions of the test are easy to understand. The test is
self-paced, therefore the child determines his or her own level of exertion.
The duration of the task is short, i.e. 6 minutes. The complete test procedure
takes 15 minutes and will take place during Physcial Eexercise classes during
school hours, with one of their parents present. The activity requested for
the test also takes place in everyday life. During the test the child is
observed continually.