Effects of 12 weeks of upper-body rowing exercise on autonomic cardiovascular control and vascular structure in spinal cord-injured humans.

Spinal cord injury (SCI) is characterized by autonomic cardiovascular dysfunction that may contribute to the three- to fourfold greater risk of heart disease and stroke compared to non-injured individuals. While exercise training elicits beneficial changes in autonomic function and vascular structure in healthy individuals, it is unclear if similar adaptations occur in individuals with SCI. Adults with chronic SCI (>1 year post injury) were randomized to 12 weeks of supervised upper-body rowing exercise (UBROW; 3×/week; n = 8), adhering to current exercise guidelines, or control (CON; n = 9). Autonomic cardiovascular control was assessed by heart rate variability (HRV; electrocardiography) and blood pressure responses to a sit-up test (finger plethysmography). Brachial (peripheral) and carotid (central) artery diameter and wall thickness (near- and far-wall carotid intima-media-thickness) were measured using high-resolution ultrasound. All measurements were conducted at baseline, after 6 and 12 weeks. There was no effect of UBROW on time and frequency domain HRV or blood pressure responses to the sit-up test (group-by-time interactions: P ≥ 0.28; effect sizes: η  ≤ 0.11). For UBROW, brachial artery diameter increased from 4.80 ± 0.72 mm at baseline to 5.08 ± 0.91 mm after 12 weeks (P < 0.05, η = 0.27). Carotid artery dimensions did not change, and there were no correlations between changes (baseline-12 weeks) in brachial artery diameter and changes in HRV outcomes (r ≤ 0.40, P ≥ 0.14). While upper-body rowing exercise enlarged brachial artery diameter, carotid artery dimensions and autonomic cardiovascular control did not change, suggesting local vascular remodelling, but no systemic vascular adaptations, in response to a supervised 12-week exercise intervention in spinal cord-injured humans.