Implementation of Physical Activity Guidelines for Spinal Cord Injury: Effects on Vascular Structure and Function

Abstract

Objective: To determine the effects of implementing 4-months of the physical activity guidelines (PAG) on vascular-health outcomes in adults with spinal cord injury (SCI). Design: Randomized controlled trial. Setting: McMaster University. Participants: Twenty-three persons with SCI (NLI C3-T11, AIS A-C, YPI 12.0 +/- 9.9 years, age 41.4 +/- 11.6 years). Interventions: Participants were randomized into PAG (n=12) or active control (CON, n=11) for 4-months. PAG training involved 2x/wk of >20min of moderate-vigorous aerobic exercise (RPE 3-6) and 3x10reps of strength exercises for upper-body muscles. The CON group maintained existing physical activity levels with no guidance on training intensity. Main Outcome Measure(s): Vascular health indicators of arterial structure via local compliance and regional stiffness, and arterial function via local endothelial functionweremeasured at baseline and after 4-months of training. Results: No baseline differences between groups or changes over time within groups were found in arterial structure (carotid compliance, regional stiffness) or function (arm and leg endothelial function). However, a trend was found for measures of carotid artery compliance (group x time interaction p=0.07), in which improvements in local carotid artery compliance were seen in the PAG group concurrent with declines in local carotid artery compliance in the CON group. Conclusions: Four months of implementation of the PAG in adults with SCI is insufficient to improve peripheral vascular structure and function. However, there was an indication of trends towards positive local carotid artery compliance changes with 4-months of the PAG. The PAG should continue to be promoted as a means to increase physical activity, but may need to be modified for vascular health improvements. Increases in the duration and/or intensity of the aerobic exercise component of the existing PAG may be needed to improve vascular health outcomes in adults with SCI.