Healthy subjects will be invited to fill out a questionnaire regarding falls and balance skills followed by normal walking trials on a treadmill at 9 different speeds (0.28-1.4 m/s). Key gait parameters for the normative database will be collected. During the perturbation trials, the subjects will walk at a constant speed (1.2 m/s). The treadmill belts are ac, - or decelerated during the perturbations according to three different perturbation algorithms with varying perturbation onset. Movements will be analyzed by 3D motion capture, force plates, surface electromyography and IMU sensors. All methods are non-invasive and commonly used in the field of biomechanics.

Inclusion Criteria:

• Healthy subjects aged 18-40 years and 60-80 years
• Ability to walk at minimum 30 minutes at a regular pace without assistance or breaks
• Written informed consent as documented by signature (see informed consent form)

Exclusion Criteria:

• Women who are pregnant or breast feeding
• Current neurological problems affecting walking function and balance
• Current orthopedic problems affecting upper and lower extremity movements
• History of alcohol abuse or the intake of psychotropic drugs
• History of major cardiac condition (e.g., infarction, insufficiency (NYHA II-IV))
• History of major pulmonary condition (e.g., chronic obstructive pulmonary disease (GOLD II-IV))
• Current major depression or psychosis
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia
• Fever of unknown origin

Healthy population