Author(s): ELY, M., BURNS, K., YATES, B., TAYLOR, A., Institution: PROVIDENCE COLLEGE, Country: UNITED STATES, Abstract-ID: 341

INTRODUCTION:
An elevated red blood cell distribution width (RDW, >14%) is associated with cardiovascular disease and mortality. Individuals with spinal cord injuries (SCI) are reported to have an elevated RDW, and in non-injured populations aerobic exercise training has been shown to decrease RDW. However, a direct RDW comparison between those with SCI and non-injured individuals has not been completed, nor has a longitudinal assessment of RDW following aerobic exercise training. Therefore, the purpose of this investigation was to 1) cross-sectionally compare RDW in individuals with SCI and anthropometrically matched non-injured individuals and 2) longitudinally monitor changes in RDW in individuals with SCI performing 6-months of aerobic exercise training.
METHODS:
In the cross-sectional comparison, hematological parameters including red blood cell number, volume, hematocrit, hemoglobin, and RDW were measured in twenty-five individuals with SCI and a cohort of 22 non-injured individuals that were anthropometrically matched for sex, age, and body mass index. In the longitudinal portion, thirty-seven individuals with SCI performed 6-months of hybrid functional electrical stimulation rowing (FES) aerobic exercise. Hematological assessments as well as measures of aerobic fitness (VO2peak) were performed prior to participation as well as following 3- and 6-months of FES. Exercise was performed 2-3 times per week for >20 minutes. Exercise intensity increased from 60-70% to 75-90% of heart rate peak as obtained during VO2 testing. Exercise intensity was additionally adjusted at 3-months based on VO2 testing.
RESULTS:
Individuals with SCI displayed an elevated RDW (13.5±1.4%) compared to matched non-injured individuals (12.5±0.4%, P=0.005). Additionally, in individuals with SCI (n=37), RDW decreased following 6-months of aerobic exercise training (Pre:14.2±0.3%, Post:13.6±0.2%, P=0.009). Aerobic capacity increased with 6-months of aerobic training in all individuals (1.22±0.07 to 1.37±0.07 L·min-1, P<0.001) but the magnitude of increase was greater in those with pre-training RDW <14% (n=18, +0.19±0.03 L·min-1) compared to those with elevated RDW >=14.0% (n=19, +0.11±0.02 L·min-1, P=0.040).
CONCLUSION:
RDW is elevated in individuals with SCI and was reduced with 6-months of aerobic exercise training. An elevated RDW at the initiation of aerobic exercise training may limit cardiorespiratory gains with training. Although it is unknown if an elevated RDW is the cause or consequence of disease, routine clinical assessment of RDW appears to be a useful biomarker to monitor cardiovascular health in individuals with SCI.