Central Command During Exercise: Hierarchical Integration of Feedforward and Feedback Cardiovascular Control

Cardiovascular regulation during exercise has traditionally been explained by the interaction between central command, a feedforward neural mechanism originating in higher brain centers, and peripheral cardiovascular reflexes, particularly the exercise pressor reflex and arterial baroreflex. Although central command is widely recognized as initiating autonomic adjustments in proportion to perceived effort, accumulating evidence indicates that its role extends well beyond the generation of parallel autonomic drive. In this review, we synthesize experimental findings spanning spinal and brainstem neurophysiology to integrative studies in intact animals and humans, showing that descending signals associated with central command may access the neural circuitry involved in processing peripheral cardiovascular information and regulating autonomic output. Neurophysiological studies identify multiple sites of interaction, including inhibitory gating of group III/IV muscle afferent transmission within the spinal dorsal horn and modulation of barosensory processing within the nucleus of the solitary tract. At the integrative level, studies of the arterial baroreflex, exercise pressor reflex, and trigeminally mediated diving reflex further demonstrate that central command can selectively regulate reflex expression and modify interactions among competing autonomic inputs rather than summating with them. Together, these observations support a conceptual evolution of central command from a feedforward initiator to a hierarchical autonomic organizing system (CHAOS) that dynamically integrates central command with peripheral cardiovascular feedback according to behavioral context. This CHAOS framework provides a unifying physiological interpretation for findings traditionally considered within individual reflex systems and offers a broader perspective on cardiovascular regulation during exercise and other conditions imposing competing autonomic demands.