Inclusion Criteria:  diagnosis of possible or probable MSA-P (Gilman 2008) or clinically established PD (Postuma 2015); 50 to 80 years of age; laboratory-confirmed symptomatic (i.e. OHQ - OH Symptom Assessment item #1 ≥ 4), neurogenic OH at screening visit or previously diagnosed as such (i.e. neurogenic OH ratio [≤ 0.492 Δ heart rate rise/systolic BP fall] or missing BP overshoot at phase IV of Valsalva maneuver; stable medication schedule in the preceding 3 weeks; no infectious disease in the preceding 3 weeks; Hoehn & Yahr stage ≤ 3; gait item of the Unified MSA Rating Scale (UMSARS) Part II or the Movement Disorder Society - Unified PD Rating Scale (MDS-UPDRS) Part III score < 3; body sway item of the UMSARS II/MDS-UPDRS III score < 3; arising from chair item of the UMSARS II/MDS-UPDRS III score < 3; full legal capacity; written informed consent has been obtained.  Exclusion Criteria:  participation in other interventional trials; prescribed and regular use of abdominal binders OR compression stockings for OH treatment; other major neurologic or psychiatric diseases which could influence OH or gait; untreated diabetes mellitus with clinical features of peripheral neuropathy; non-neurological causes of gait disorders; major cardiac diseases (ischemic, structural, arrhythmias); evidence of varices (venous insufficiency stage ≥ C2, "varicose veins"); known abdominal aortic aneurism; indwelling catheterisation; recent surgery (3 months) requiring anaesthesia; known or suspected pregnancy; breast-feeding female participants.