Salivary cortisol response and VO2max during standardized excercise test in children with and without asthma

It is known that children with asthma have attenuated short term and long term
basal cortisol levels (Heijsman 2011, Bakkeheim, Kamps]. The clinical relevance
of this finding is unclear. However, recently we demonstrated that children
with asthma also have attenuated salivary cortisol repsonses during
standardized exercise tests (NL 37156.000.11, Hiemstra et al, submitted).
Children with asthma had a shorter time to exhaustion despite the fact that
they had stable asthma and had no restrictions in physical exercise
(participated in community sports and performed physicla exercise at school)
The intriguing question is why children with asthma had a shorter time to
exhaustion. Children with asthma have been shown to be just as physically
active as their healthy counterparts.[van Gent] Is their exercise capacity
really limited or is it their perception and do they stop exercise to prevent
potential symptoms of asthma.
Few studies have evaluted the physcial condition of children with asthma.
Children with untreated asthma appeared to have a lower exercise
capacity.[Vahlkvist] On the other hand, children with stable asthma had a
VO2max comparable to their healthy counterparts.[Berntsen] In another study the
exercise capacity between children with asthma and healthy children was
comparable provided that the daily physical activity was comparable.[Santuz]
It has been reported that lower basal cortisol levels have a deleterious effect
on pulmonary function.[Landstra] Hypothetically, the attenuated cortisol
respons of children with asthma may affect the exercise capacity. Indeed,
Pritis et al have demonstrated that a substantial number of children with
asthma have attenuated adrenal responses which improve during maintenace
treatment with inhaled corticosteroids.[Priftis]
To further elucidate whether the attenuated salivary cortisol reponse is due to
attenuated exercise capacity we want to compare the salivary cortisol responses
of children with asthma and healthy children, and also compare the physcial
condition of the children by measuring VO2max.

To determine whether the attenuated salivary cortisol response in children with
asthma can be explained by the maintenance use of inhaled cortiocosteroids, the
chronic inflammatory disease, or the attenuated exercise capacity.

observational study

exercise test
saliva will be colected before and after the 20 meter shuttle run test
VO2max will be detrmined during teh cycle test

We expect no risk for the children as only children who are used to perform
physical exercise during community sports and/or physcial exercise lessons at
school will be included