A modified step-ramp-step protocol to prescribe constant-speed exercise in treadmill running.

Purpose: This study investigated whether a running-adapted version of the cycling-based "step-ramp-step" (SRS) protocol would improve prediction of O in treadmill exercise compared to the traditional prescriptive approach.

Methods: Fourteen healthy individuals (6 females; 25 ± 6 years; 66.1 ± 12.7 kg) performed a treadmill-based SRS protocol including a ramp-incremental test to task failure followed by two constant-speed bouts within the moderate-(MOD-below estimated lactate threshold; θ), and heavy-intensity domains (HVY-between θ and respiratory compensation point; RCP). Using the uncorrected O-to-speed relationship from the ramp exercise, three constant-speed bouts were performed at 40-50% between: baseline and θ (CSE); θ and RCP (CSE); and RCP and peak (CSE). For CSE, CSE, and CSE measured end-exercise O was compared to predicted O based on the: (i) "SRS-corrected" O-to-speed relationship (where MOD and HVY were used to adjust the O relative to speed); and (ii) linear "uncorrected" data.

Results: Average treadmill speeds for CSE and CSE were 7.8 ± 0.8 and 11.0 ± 1.4 km·h, respectively, eliciting end-exercise O of 1979 ± 390 and 2574 ± 540 mL·min. End-exercise O values were not different compared to SRS-predicted O at CSE (mean difference: 5 ± 166 mL·min; p = 0.912) and CSE (20 ± 128 mL·min; p = 0.568). The linear "uncorrected" estimates were not different for CSE (- 91 ± 172 mL·min; p = 0.068) but lower for CSE (- 195 ± 146 mL·min; p < 0.001). For CSE (running speed: 13.8 ± 1.7 km·h), the end-exercise O was not different from peak O achieved during the ramp (3027 ± 682 vs. 2979 ± 655 mL·min; p = 0.231).

Conclusion: In healthy individuals, the SRS protocol more accurately predicts speeds for a target O compared to traditional approaches.