Inclusion Criteria:  Severe sepsis defined as:  2 of 4 Systemic Inflammatory Response Syndrome criteria, a confirmed or clinically suspected source of infection and, two or more organ dysfunction (using standard definitions).  Exclusion Criteria:  Greater than 48h since severe sepsis criteria were met inability to perform passive exercise using bedside leg cycle, limitations on life support interventions (No CPR or No defibrillation by themselves are not an exclusion), major limitation in neurologic or physical function prior to onset of severe sepsis (e.g. wheelchair or nursing home dependent), patients receiving neuromuscular blocking drugs or sedation targeted to a MAAS score less than 3, allergies to sulfonamide drugs or iodides due to possibility of an allergic reaction to ICG.