Rethinking aerobic exercise intensity prescription in adults with spinal cord injury: time to end the use of “moderate to vigorous” intensity?

Abstract

Abstract Study design Cohort study. Objectives To investigate and critique different methods for aerobic exercise intensity prescription in adults with spinal cord injury (SCI). Setting University laboratory in Loughborough, UK. Methods Trained athletes were split into those with paraplegia (PARA; n = 47), tetraplegia (TETRA; n = 20) or alternate health condition (NON-SCI; n = 67). Participants completed a submaximal step test with 3 min stages, followed by graded exercise test to exhaustion. Handcycling, arm crank ergometry or wheelchair propulsion were performed depending on the sport of the participant. Oxygen uptake (V̇O2), heart rate (HR), blood lactate concentration ([BLa]) and ratings of perceived exertion (RPE) on Borg’s RPE scale were measured throughout. Lactate thresholds were identified according to log-V̇O2 plotted against log-[BLa] (LT1) and 1.5 mmol L−1 greater than LT1 (LT2). These were used to demarcate moderate (<LT1), heavy (>LT1, < LT2) and severe (>LT2) exercise intensity domains. Results Associations between percentage of peak V̇O2 (%V̇O2peak) and HR (%HRpeak) with RPE differed between PARA and TETRA. At LT1 and LT2, %V̇O2peak and %HRpeak were significantly greater in TETRA compared to PARA and NON-SCI (P < 0.05). The variation in %V̇O2peak and %HRpeak at lactate thresholds resulted in large variability in the domain distribution at fixed %V̇O2peak and %HRpeak. Conclusions Fixed %V̇O2peak and %HRpeak should not be used for aerobic exercise intensity prescription in adults with SCI as the method does not lead to uniform exercise intensity domain distribution.