Comparison of two Borg exertion scales for monitoring exercise intensity in able-bodied participants, and those with paraplegia and tetraplegia

Study design Cross-sectional cohort study. Objectives To compare ratings of perceived exertion (RPE) on Borg's 6-20 RPE scale and Category Ratio 10 (CR10) in able-bodied (AB) participants during upper and lower body exercise, and recreationally active participants with paraplegia (PARA) and athletes with tetraplegia (TETRA) during upper body exercise only. Setting University and rehabilitation centre-based laboratories in UK and Netherlands. Methods Twenty-four participants were equally split between AB, PARA, and TETRA. AB performed maximal tests using cycle (AB-CYC) and handcycle (AB-HC) ergometry. PARA and TETRA performed maximal handcycle and wheelchair propulsion tests, respectively. Oxygen uptake (V?O-2) and blood lactate concentration were monitored throughout. RPE was rated each stage on Borg's RPE scale and CR10. Thresholds were identified according to log-V?O-2 plotted against log-blood lactate (LT1), and 1.5 mmol L-1 greater than LT1 (LT2). Results RPE from both scales were best fit against each other using a quadratic model, with high goodness of fit between scales that was independent of exercise mode and participant group (range R-2: 0.965-0.970, P < 0.005). Though percentage peak V?O-2 was significantly greater in TETRA (P < 0.005), there was no difference in RPE at LT1 or LT2 between groups on Borg's RPE scale or CR10. Conclusion Strong association between Borg's RPE scale and CR10 suggests they can be used interchangeably. RPE at lactate thresholds were independent of mode of exercise and level of spinal cord injury. However, inter-individual variation precludes from making firm recommendations about using RPE for prescribing homogenous exercise intensity.