A "Step-Ramp-Step" Protocol to Identify the Maximal Metabolic Steady State

Area of Science:

• Exercise Physiology
• Sports Science
• Metabolic Testing

Background:

• The oxygen uptake (V̇O2) at the respiratory compensation point (RCP) is a key indicator of maximal metabolic steady state.
• Traditional ramp-incremental exercise protocols struggle to accurately determine the power output (PO) at RCP.

Purpose of the Study:

• To evaluate the effectiveness of a novel "step-ramp-step" (SRS) cycling protocol for estimating the PO at RCP.
• To validate the use of RCP as a surrogate for maximal metabolic steady state.

Main Methods:

• Healthy volunteers performed a "step-ramp-step" protocol involving moderate and heavy intensity steps with an intervening ramp test.
• Ventilatory and gas exchange data were analyzed to determine V̇O2 at lactate threshold (LT) and RCP.
• Power output at RCP was extrapolated using linear regression between LT and heavy intensity data.

Main Results:

• Participants completed 30-minute constant-power tests at the SRS-estimated RCP, achieving a steady-state V̇O2 comparable to ramp-identified RCP values.
• Exercise at 5% above the SRS-estimated RCP resulted in incomplete trials and non-steady-state responses in most participants.
• The SRS protocol demonstrated high within-participant consistency for V̇O2 at RCP.

Conclusions:

• The SRS protocol accurately predicts the power output associated with maximal metabolic steady state in healthy individuals.
• The respiratory compensation point (RCP) serves as a valid surrogate for maximal metabolic steady state during cycling.
• The SRS protocol offers a reliable method for determining critical exercise intensity thresholds.