Ventilatory and plasma lactate response with different exercise protocols: a comparison of methods.

Area of Science:

• Exercise Physiology
• Sports Science
• Biophysics

Background:

• Accurate identification of exercise intensity thresholds is crucial for performance assessment and training.
• Various methods exist to determine ventilatory and lactate thresholds, but their agreement is not fully established.

Purpose of the Study:

• To compare different methods for identifying abrupt changes in ventilation and plasma lactate during incremental exercise.
• To evaluate the consistency of ventilatory threshold 1 (VT1) and ventilatory threshold 2 (VT2) with lactate threshold (LT), onset of blood lactate accumulation (OBLA), and individual anaerobic threshold (IAT).

Main Methods:

• Ten males performed incremental cycle ergometer tests of 1-, 3-, and 5-min duration to fatigue.
• Ventilatory thresholds (VT1, VT2) were determined using plots of ventilation (VE), VE/VO2, excess CO2, and VE/VCO2.
• Lactate thresholds (LT, OBLA, IAT, OPLA) were determined from arterialized blood samples analyzed at various time points and exercise intensities.

Main Results:

• VO2max was significantly higher in the 1-min test compared to 3- or 5-min tests.
• VT1 determined from VE or VE/VO2 vs VO2 were similar, but significantly lower when using excess CO2.
• VO2 at LT and OPLA were similar to VT1 derived from VE or VE/VO2 vs VO2.

Conclusions:

• The method of calculating VT1 influences its value, with excess CO2 yielding lower results.
• Lactate-based thresholds (LT, OPLA) demonstrate good agreement with VT1 derived from ventilation and oxygen consumption.
• Incremental test duration may affect VO2max but not necessarily the relative exercise intensity thresholds.