Evaluation of the "Step-Ramp-Step" Protocol: Accurate Aerobic Exercise Prescription with Different Steps and Ramp Slopes

The step-ramp-step (SRS) can assign constant-load exercise intensities from a ramp-incremental test. Its precision using different moderate-intensity (MOD) steps or ramp slopes has yet to be evaluated. Purpose To assess whether: i) a lower amplitude constant-load MOD is appropriate to determine the mean response time (MRT); ii) the method accurately corrects the dissociation in the VO₂-PO relationship during ramp compared with constant-load exercise when using different ramp slopes. Methods Eighteen participants (7 females) performed three SRS tests including: i) step-transitions into MOD from 20 to 50 W (MOD₅₀) and 80 W (MOD₈₀); and ii) slopes of 15, 30, and 45 W·min^-1. The VO₂ and PO at the gas exchange threshold (GET) and the corrected respiratory compensation point (RCP_CORR) were determined. Two to three 30-min constant-load trials evaluated the VO₂ and PO at the maximal metabolic steady state (MMSS). Results There were no differences in VO₂ at GET (1.97 ± 0.36, 1.99 ± 0.36, 1.95 ± 0.30 L·min^-1), and RCP (2.81 ± 0.57, 2.86 ± 0.59, 2.84 ± 0.59) between 15, 30, and 45 W·min^-1 ramps, respectively (P > 0.05). The MRT in seconds was not affected by the amplitude of the MOD or the slope of the ramp (range 19 ± 10 s to 23 ± 20 s; P > 0.05). The mean PO at GET was not significantly affected by the amplitude of the MOD or the slope of the ramp (range 130 ± 30 W to 137 ± 30 W; P > 0.05). The PO at RCP_CORR was similar for all conditions ((range 186 ± 43 W to 193 ± 47 W; P > 0.05). Conclusions The SRS protocol accounts for the VO₂ MRT when using smaller amplitude steps, and for the VO₂ slow component when using different ramp slopes, allowing for accurate partitioning of the exercise intensity domains in a single test.