Defining the nature of disease in older adult populations
with moderate/severe persistent asthma is made
difficult because many exhibit permanent changes in
lung function as a result of the chronicity of their asthma,
and as such they could also be considered to have
COPD [8, 9] . In recognition of this we use the term fixed
airway obstruction asthma (FAOA) to define a subject
cohort with moderate/severe disease with a component
of fixed airflow limitation. Such a definition is important
because, despite similar symptomatology [10] , individuals
with COPD and FAOA are likely to demonstrate different
responses to exercise. For example, well-preserved
gas transfer is a characteristic of asthma [11] and therefore
exercise-induced oxygen desaturation is unlikely to
occur. In contrast, a proportion of individuals with
COPD desaturate during exercise as a result of impairment
in gas transfer and this contributes to exercise limitation
[12, 13] . Such differences suggest that exercise programs designed for COPD may not be appropriate for
FAOA.