Limitations
It is possible that the low recruitment rate in this study
may have resulted in a potential bias in the study population.
A significant proportion of potential subjects were
in full- or part-time employment, and during the screening
phase many of these individuals were concerned
about the time commitment required if they were randomised
to the exercise group. However, the level of attrition
at the 3-month assessment appears comparable to
that in other studies of exercise training in adults with
asthma [31] . Another potential limitation is that subjects
randomised to the control group were not formally monitored
for any changes in their exercise habits. At the
6-week assessment, some of these individuals stated that
they had been exercising more regularly, which may have
contributed to the improvement in the activity limitation
of the AQLQ compared to baseline. Similarly, as objective
monitoring of physical activity was not performed, we are
unable to determine whether the sustained improvement
in 6MWD observed at the 3-month follow-up assessment
in the exercise group was due to these subjects being motivated
to continue to exercise regularly following cessation
of the supervised training.