T1. Objective and hypotheses Acute heart failure (AHF) is associated with the disorders of peripheral perfusion, leading to injury of many vital organs. Consequently, each episode of AHF can have a form of multiple organ failure with potential injury and dysfunction of skeletal muscles; however, this latter issue has not been addressed in literature thus far. The aim of this project is to comprehensively evaluate the skeletal muscles (at a functional and tissue level) during acute heart failure. The following hypotheses will be verified:(1) Impaired perfusion of the muscles is reflected by their injury and significant functional abnormalities; (2) Early implemented motor rehabilitation improves perfusion and function of skeletal muscles; This study will demonstrate that skeletal muscles are involved as a component of AHF-related multiple organ failure.