Effect of standardized running test on salivary cortisol respons in prepubertal children

Collection of saliva is a well established non invasive way to assess cortisol
levels in children. We have recently demonstrated that children with asthma
using topical steroids have a significantly lower basal salivary cortisol level
(Heijsman et al, submitted). The clinical relevance of this finding is unclear.
We would like to develop a noninvasive test to determine adrenal respons in
children.
We have recently demonstrated that a short standardized cycling test at
different intensities does not result in a measurable increase in salivary
cortisol levels in prepubertal children. An explanation may be that the cycling
test did not result in maximal effort. We therefore designed the present study
to determine whether a standardized running test (20 meter shuttle run test)
will elicit a signficant increase of salivary cortisol levels.

To evaluate if a standardized running test will elicit an increase in salivary
cortisol levels in healthy prepubertal children

Twenty healthy prepubertal children will be invited to participate. The
follwing patientcharacteristics will be recorded at the beginning of the
study: height, weight, body mass index and pubertal state according to Tanner
criteria. All children will have a resting period of 30 minutes is to guarantee
similar baseline conditions. During this resting period instructions will be
given about the running test and the collection of saliva.
The exercise test will be performed in the afternoon (between 16 and 17:00 hr).
This time was chosen because there would be no interference with school
attendance. Furthermore, in the afternoon the basal activity of the
hypothalamic-pituitary-adrenal axis is low and therefore expected to be more
sensitive to exercise induced stimulation.

After the first running test saliva samples will be analysed. If the running
test elicits an increase in salivary cortisol levels the children will perform
the running test again to determine the reproducibility of the salivary
cortisol response.

A running test (20 meter shuttle run test) will be performed under supervison
of a physiotherapist and one of the investigators. The shuutle run test
consists of running between two parallel lines set 20 meters apart. Running
speed is indicated by signals emitted from a commercially avialable CD rom.
Subjects start a a running speed of 8 km/h. Running speed will be increased by
0.5 km/h at one minute intervals. The children will be verbally encouraged to
perform maximally.

we do not expect any risk for the children