Heart abhors contracting during elevated intramuscular pressure: implication for cardiac-locomotor synchronization

Rhythmic intramuscular pressure changes during locomotion were simulated using a computer-controlled thigh cuff occlusion device to test the hypothesis that cardiac-locomotor synchronization (CLS) plays a functional role in the delivery of blood to active muscles. Alternating occlusion of the bilateral femoral arteries caused human heartbeats to become phase-locked with the occlusion rhythm. The synchronized phase did not include overlap between peak arterial flow velocity in the leg and elevated cuff pressure. Functional significance of CLS is discussed.