Physical and psychological predictors of daily physical activity in COPD.

Despite the high prevalence of chronic obstructive pulmonary disease (COPD)
there is a striking lack of information about the daily physical activity level
of COPD patients in various stages of their disease (GOLD 1-4). Even less is
known about the predicting factors of daily physical activity. It's not known
if mainly physical factors or psychological factors predict daily physical
activity of COPD patients, and if there are differences between the various
GOLD stages.
Also less is known about its consequences for quality of life.
We hypothesize that daily physical activity level declines gradually with
higher GOLD stages, but declines relatively sharply after reaching GOLD stage
4. Psychosocial factors contribute importantly to the variability of daily
physical activity level in GOLD 1, 2 & 3. In GOLD stage 4 the reciprocal
interaction between physical disability and psychosocial factors is
particularly responsible for the variability in the level of daily physical
activity. Health related quality of life is closely related with daily physical
activity level, much more than with FEV1 (or GOLD stage).
This information is vital for designing successful prevention and management
programs that target the symptom-induced immobility leading to reduced fitness,
depression and social isolation characteristically for COPD.

To assess in the 4 GOLD stages of COPD:
1) Performance based daily physical activity with respect tot the level, types
and intensity of daily physical activity;
2) Physical predictors for the daily physical activity status;
3) Psychosocial predictors for daily physical activity status;
4) The relationship between daily physical activity status and health related
quality of life.

Observational study without a therapeutic intervention.

- Totally the study exists of three visits; one at home and within six weeks
two visits will take place at the UMCG hospital.
The first visit will take 2 hours, the second 2,5 hours and the third 1,5 hour.
Between the second and third visit the subjects will ask to wear a pedometer
(for 2 weeks) and a accelerometer (for 1 week).
- The six-minute-walking test and the bicycle ergometer requires strenuous work
output.