Muscle function in relation to daily activity patterns of the upper and lower extremities in COPD patients.

Physical inactivity in healthy subjects increases the risk of developing a
number of chronic diseases, such as chronic obstructive pulmonary disease
(COPD). Indeed, physical inactivity is one of the lifestyle-related health
determinants. Therefore, guidelines recommend that a minimum of 30 minutes of
daily physical activity of moderate intensity is necessary to maintain physical
fitness, and those not meeting this standard are considered insufficiently
active.

Decreased activity in daily life is likely to play a key role in the
development and progression of skeletal muscle weakness and a poor exercise
performance in patients with COPD. Indeed, a *downward disease spiral* has been
hypothesized, in which advancing dyspnoea leads to a sedentary lifestyle and
de-conditioning of the muscles, and thus further daily physical inactivity.
Exercise-based pulmonary rehabilitation programs have been shown to effectively
improve quality of life, muscle function and exercise capacity in patients with
COPD which cannot be attributed to changes in forced expiratory volume in the
first second (FEV1). Moreover, studies of skeletal muscle impairment in COPD
have demonstrated that upper limb muscles were less affected than lower limb
muscles (strength, endurance and exercise capacity). It is unknown whether and
to what extent differences in muscle dysfunction between arm and leg muscles
reflect a difference in their daily use or an innate difference in the
susceptibility to disease.

To evaluate whether and to what extent differences in muscle dysfunction
between arm and leg muscles in COPD patients reflect a difference in their
daily use, daily physical activity in relation to muscle function needs to be
assessed. At present, a wide range of test models and protocols is being used
for quantification of muscle strength and endurance in COPD patients. To
minimise the impact of the muscle contractions on the cardiopulmonary systems
(which is limited in COPD patients compared to healthy controls), an endurance
protocol based on localised isometric contractions will be used. For the
assessment of daily arm and leg activity, two wearable unobtrusive sensors will
be used which provide information on motion intensity, duration (sec.) and
orientation of the upper arm and leg. It is hypothesized that preservation of
upper limb compared to lower limb muscle function is associated with
preservation of functional arm use compared to functional leg use in daily life
in patients with COPD compared to healthy controls.

Primary objective:
Test whether preservation of upper limb compared to lower limb muscle function
is associated with preservation of functional arm use compared to functional
leg use in daily life in patients with COPD compared to healthy controls.

Secondary objectives:
- Compare the ratio of the m. biceps brachii and m. quadriceps femoris strength
and endurance between COPD patients and healthy controls
- Compare the development of muscle fatigue during the endurance test between
COPD patients and healthy subjects.
- Compare the ratio of the daily arm and leg use between COPD patients and
healthy controls.
- Compare the duration of active periods between COPD patients and healthy
subjects

This is a Case-control study. Muscle strength and endurance will be measured.
Furthermore daily activity patterns will be measured for 5 days.

Not applicable