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

Introduction/Purpose The oxygen uptake- (VO₂) to-power output (PO) relationship from incremental exercise needs to be adjusted to accurately prescribe constant-intensity exercise training. We assessed accuracy of a "step-ramp-step"(SRS) protocol for prescribing constant-PO exercise within moderate- (below estimated lactate threshold, θ_LT), heavy- (between θ_LT and respiratory compensation point, RCP), and severe-intensity (above RCP) domains in fourteen patients with coronary artery disease (CAD). Methods The SRS protocol included in series: 6-min of cycling at 25-40 W, a ramp-incremental test until task failure (5-15 Wmin^-1), and, after 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%θ_LT (moderate-intensity, MOD), 70% of the difference between θ_LT and RCP (heavy-intensity, HVY), and 115%RCP (severe-intensity, SEV). Measured VO₂ for: MOD and HVY were compared to those predicted using either SRS-corrected or uncorrected approaches; and, for SEV, were compared to peak ramp VO₂. Results The POs for MOD, HVY, and SEV were 53 ± 27 W, 96 ± 50 W, and 116 ± 56 W, respectively, eliciting VO₂ of 1012 ± 362 mL·min^-1, 1541 ± 638 mL·min^-1, 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-to-PO relationship from incremental exercise must be corrected to prescribe constant intensity training. The SRS protocol is an accurate approach to ensure prescriptive accuracy.