measured by the time needed to cross a traffic light (distance: 11m)

intensity of perceived tension symptoms experienced when crossing a traffic light (VAS scale, ranging from 0 to 10)

measured by the sit-to-stand test, test duration: 1 minute

measured by the microfet, knee Extension

Anxiety/Depression measured by Hospital Anxiety and Depression Scale (HADS) - a screening questionnaire including seven questions each about Depression and Anxiety; each part ranging from 0 to 21; higher scores indicate higher presence of the respective state

measured by Fried Frailty Phenotype (FFP), including five constructs (weight loss, exhaustion, physical activity, gait speed and weakness); range 0-5, higher scores reflect increased Frailty: A score of 0 is considered as "robust", a score of 1-2 is considered as "pre-frail", a score lower than 2 reflects "Frailty"

assessed by the Chronic Respiratory Disease Questionnaire (CRQ)- a 20-item self-report questionnaire; score 1-7; higher scores indicate a better health-related quality of life

assessed by the Illness perception Questionnaire, revised (IPQ-R) - 18 items, score 1-5; higher scores indicate a worse illness perception, except of item 7,9,10,11,12.

assessed by the German "COPD Angst Fragebogen" (CAF) - a 20-item self-report questionnaire, rated on a Lickert-scale (score 0-4); highest maximum score: 80 points; higher scores indicate higher anxiety levels.