Although in able-bodied individuals heart rate (HR) indicates exercise intensity, the linearity of the HR/oxygen uptake (VO2) relationship has not been established in persons with quadriplegia with impaired sympathetic function. The HR/VO2 relationship and four ACSM recommended methods of exercise prescription were evaluated in 11 individuals with quadriplegia during intermittent progressive peak exercise tests. Tests were conducted in either a supine or sitting position using an arm ergometer. The HR response was highly variable, with HR/VO2 correlation coefficients ranging from 0.22 to 0.99. A 2 x 2 ANOVA revealed an interaction between injury level, high-level (above C7) vs low-level (C7 and below) and exercise position, with the high-level group exhibiting the lower coefficient (0.68) between the HR/VO2 relationship in the sitting position. For all subjects, the target of 55-90% peak HR (mean = 72.5%) corresponded to 34% peak power output (PO) in sitting and 44% peak PO in supine. Similarly, 70% peak VO2 corresponded to 46% and 50% of peak PO (sitting and supine, respectively). A rating of perceived exertion (RPE) of 10-12 corresponded to 50-60% peak PO and was associated with a higher PO than that predicted by the HR or VO2 methods. The results of this study indicate that exercise intensity for quadriplegics be based on 50-60% peak PO and/or an RPE of 10-12.