Exercise-induced oxidative stress and peripheral muscle dysfunction in COPD; single-leg ergometer test versus whole-body exercise test.

Peripheral muscle dysfunction, which is now recognized as one of the main
systemic effects of chronic obstructive pulmonary disease (COPD), contributes
greatly to the exercise intolerance and reduced quality of life of COPD
patients. This peripheral muscle dysfunction in COPD has primarily been
explained by the sedentary lifestyle commonly observed in patients. However,
evidence has been accumulating that a sedentary lifestyle is unlikely to be the
sole factor involved in the myopathy of COPD patients. One hypothesis is that
exercise-induced oxidative stress can result in structural and functional
muscle abnormalities in COPD.

To investigate (1) whether basal levels of oxidative stress differs between
COPD patients and healthy volunteers and (2) whether exercise-induced oxidative
stress after a single-leg ergometer test differs between patients and healthy
controls (3) to compare the effects of a single-leg ergometer test versus a
whole-body exercise test on oxidative stress and (4) to determine whether this
oxidative stress contributes to muscle dysfunction (reduced endurance time) in
patients with COPD.

This proposed study is a patient-control study, where the acute effects of
exercise-induced oxidative stress markers will be evaluated.

Visit 1 (only for healthy volunteers): Medical history, smoking history,
physical examination, electrocardiogram, fasting blood sample, lung function
test, anthropometric measurements, questionnaire on their dietary habits and
physical activity level. Subjects will then undergo a maximal symptom-limited
incremental exercise test on a bicycle ergometer.
Visit 2: All subjects will re-attend at least 72 hours later to perform a
submaximal (60%) cycle ergometer test.
Visit 1 is included in the rehabilitation program for the COPD patients, with
the exception of the questionnaire on their dietary habits and physical
activity level.
WEEK 2: Visit 3: Subjects will perform a maximal single-leg ergometer test.
Three hours later a submaximal single-leg ergometer test (40%) will be
performed to assess the approximately duration time. Based on the outcome of
this exercise test we will divide the COPD patients into 2 groups. One group
has to cycle for 5 minutes (fatiguers) and the other group has to cycle for 20
minutes (non-fatiguers). These two time points are based on the results of a
pilot study.
Visit 4: At least 72 hours later subjects will perform a submaximal (40%)
single-leg ergometer test.
Sampling of blood, urine and exhaled breath
Urine and venous blood samples (10 ml) will be sampled at baseline, and at two
time points (immediately after, 2h after) after submaximal bicycle ergometer
test (visit 2). For the single-leg ergometer exercise test (visit 4), urine and
venous blood will be samples at baseline, after 5 or 20 minutes, immediately
after and 2h after. The blood sampling will occur through an insertion of a
cannulla into the vein. Exhaled breath will be sampled before, immediately
after and 2h after both exercise tests. The sampling of blood, urine and breath
condensate is virtually without any risks.