Exercise reconditioning of the heart and peripheral circulation after spinal cord injury

The human cardiocirculatory system adapts to sustained underloading of volume and pressure by altering its structure and function. Such underloading, predictable structural adaptation, and departure from normal function have all been reported in survivors of spinal cord injury (SCI). Conditioning exercise reportedly reverses the adaptive left ventricular atrophy accompanying tetraplegia and increases the stroke volume contribution to, but not the cardiac output of, persons with paraplegia. The accumulated effects of intermittent exercise also chronically improve resting blood flow and its regulation in conditioned extremities of tetraplegic and paraplegic patients, regardless of whether the training occurs in muscle contracting under voluntary command or is evoked by electrically stimulated contractions. Such changes mimic those reported in persons without SCI who undergo conditioning exercise and benefit the cardiac and peripheral circulatory structure and function of survivors of SCI.