A Protocol to Establish Exercise Intensity Domains for Aerobic Exercise Training in Coronary Artery Disease

Introduction/Purpose The oxygen uptake (VO2)-power output (PO) relationship from incremental exercise needs to be adjusted to accurately prescribe constant-intensity exercise training. We assessed the accuracy of a "step-ramp-step"(SRS) protocol for prescribing constant PO exercise within moderate-intensity (below estimated lactate threshold, θLT), heavy-intensity (between θLT and respiratory compensation point, RCP), and severe-intensity (above RCP) domains in 14 patients with coronary artery disease (CAD). Methods The SRS protocol included the following: 6 min of cycling at 25-40 W, a ramp-incremental test until task failure (5-15 W min-1), and, after a 20 min recovery, 12 min of cycling at ∼50%-60% of peak ramp PO. On separate days, patients performed three domain-specific constant PO exercises at 80% θLT (moderate intensity [MOD]), 70% of the difference between θLT and RCP (heavy intensity [HVY]), and 115% RCP (severe intensity [SEV]). Measured VO2 values for MOD and HVY were compared with those predicted using either SRS-corrected or uncorrected approaches and, for SEV, were compared with peak ramp VO2. Results The PO values for MOD, HVY, and SEV were 53 ± 27, 96 ± 50, and 116 ± 56 W, respectively, eliciting VO2 of 1012 ± 362, 1541 ± 638, and 1944 ± 744 mL min-1. The SRS-corrected predictions did not differ from measured VO2 for MOD (-25 ± 61 mL min-1; P = 0.201) or HVY (-40 ± 89 mL min-1; P = 0.208), whereas uncorrected predictions underestimated VO2 by -128 ± 72 mL min-1 (P = 0.002) and -199 ± 99 mL min-1 (P = 0.001) in MOD and HVY, respectively. Peak VO2 from SEV did not differ from the ramp (1906 ± 766 mL min-1; P = 0.759). Conclusions In CAD, the VO2-PO relationship from incremental exercise must be corrected to prescribe constant-intensity training. The SRS protocol is an accurate approach to ensure prescriptive accuracy.