2015 Parapan American Games: Does Physical Activity Participation Improve Cerebrovascular Function after High‐Level Spinal Cord Injury?
Authors: Phillips Aaron , Squair Jordan W , Currie Katharine , Tzeng Shieak YC , Ainslie Philip N , Krassioukov Andrei V 
Published: November 2023

Introduction

The risk of stroke is elevated 3–4 fold after spinal cord injury (SCI), and cognitive dysfunction is widespread. Using human and experimental animal models, we have previously established that cerebrovascular function is impaired after SCI, and is related to cognitive decline. Lower physical activity is thought to be associated with cerebrovascular complications in a number of clinical populations, however no link to cerebrovascular function has been established in those with SCI. Neurovascular coupling (NVC) and dynamic cerebral autoregulation (dCA) are established metrics for evaluating cerebrovascular function in humans. While NVC describes the efficacious matching of cerebral blood flow (CBF) to changes in neuronal activation, dCA reflects the capacity of the cerebrovasculature to buffer transient changes in blood pressure (BP). The appropriate control of CBF in the face of rapidly changing metabolic requirements and BP is thought to underlie cognitive performance as well as protect the delicate cerebral microvessels.

Objective

Examine the role physical activity plays in cerebrovascular function after SCI.

Methods

Through a field study at the 2015 Parapan American Games, we compared some of the most physically active SCI individuals in the world (consisting of 9 wheelchair rugby national teams [SCIa; n=19]), relatively inactive SCI controls (SCIb; n=9), and age‐matched able‐bodied individuals (AB; n=11). Both SCI groups suffered motor complete SCI (>T6 spinal segment). In the seated position, blood velocities in the middle and posterior cerebral arteries (MCA, PCA; transcranial Doppler and beat‐by‐beat BP (photoplethymography)) were recorded continuously. Thereafter, validated tests of NVC (visual stimulation), dCA (transfer function analysis), attention/concentration (Stroop test) and moderate to vigorous physical activity (MVPA; Godin‐Shephard questionnaire) were completed.

Results

The SCIa group was dramatically more physically active (62±3 au) than both SCIb (22±4 au, p<0.05) and AB (34±7 au, p<0.05). NVC was reduced 31% and 23% in SCIa and SCIb compared to AB, respectively (both p<0.01, Figure 1A), however NVC was similar between the SCI groups. For the PCA but not the MCA, over a range of frequencies, SCIa consistency demonstrated improved buffering of the cerebrovasculature. These changes were reflected in a 27–37% (all p<0.01, Figure 1B) reduced coherence‐weighted normalized gain, indicative of a reduced influence of BP on posterior cerebral circulation. Stroop performance was reduced 27% in SCIb (P3‐P2 time, p<0.05) but was preserved in SCIa when compared to AB.

Conclusions

Our data demonstrate that physically active individuals with SCI exhibit improved dCA and cognitive function; these changes may help compensate for the persistent impairment in NVC and thereby prevent vascular cognitive decline. The present findings have important implications in furthering our understanding of the favorable impact of exercise on cerebrovascular health in SCI.

Support or Funding Information

HSF‐Canada, CNF, CIHR, MSFHR