A simplified approach for estimating the ventilatory and respiratory compensation thresholds

Area of Science:

• Exercise Physiology
• Sports Science
• Biophysics

Background:

• Physiological thresholds like ventilatory (VT) and respiratory compensation (RCT) are crucial for optimizing training intensity.
• Traditionally, these thresholds are determined using complex gas exchange analysis.
• Identifying simpler, accessible methods to estimate these thresholds is valuable for athletes and coaches.

Purpose of the Study:

• To investigate if ventilatory (VT) and respiratory compensation (RCT) thresholds can be accurately derived from percentages of maximal running speed (Vmax).
• To assess the physiological responses during sustained running at intensities corresponding to VT and RCT.
• To provide practical guidelines for exercise training prescription based on Vmax.

Main Methods:

• Phase 1: Identified VT and RCT in 31 athletes using respiratory gas exchange during incremental treadmill tests.
• Phase 2: Validated findings in 20 athletes by performing 30-minute runs at velocities near VT and RCT (±2SE of Vmax).
• Measured blood lactate ([BL]), rating of perceived exertion (RPE), heart rate (HR), and speech comfort during validation runs.

Main Results:

• VT was identified at 67 ± 9% Vmax and RCT at 84 ± 6% Vmax.
• Running at 64% Vmax (below VT) allowed sustained 30-min performance with stable [BL], moderate RPE, minimal HR drift, and comfortable speech.
• Running at 86% Vmax (above RCT) led to fatigue within 18.5 min, elevated [BL], high RPE, significant HR drift, and inability to speak comfortably.

Conclusions:

• Simple percentages of maximal running speed (Vmax), specifically ≤64% and ≥86%, can serve as practical indicators for VT and RCT.
• These Vmax percentages offer a feasible alternative for prescribing exercise training intensities without requiring gas exchange analysis.
• Combining %Vmax with subjective measures like the Talk Test and RPE provides accessible tools for performance evaluation and training prescription to enhance aerobic or anaerobic capacity.