Changes in blood pH, lactate concentration and pulmonary ventilation during incremental testing protocol on cycle...

Area of Science:

• Exercise Physiology
• Biochemistry
• Respiratory Physiology

Background:

• Understanding blood pH regulation during exercise is crucial for performance.
• Lactate accumulation and changes in pulmonary ventilation are key indicators of metabolic stress.

Purpose of the Study:

• To investigate the relationship between blood lactate concentration, blood pH, and pulmonary ventilation during incremental exercise.
• To identify distinct phases in the ventilation to lactate ratio (V_E/[LA]) and their correlation with blood pH and exercise intensity.

Main Methods:

• Seven healthy subjects performed an incremental cycle ergometer test.
• Measurements included blood lactate concentration ([LA]), blood pH, and pulmonary ventilation (V_E).
• The V_E/[LA] ratio was analyzed across different exercise intensities and corresponding pH levels.

Main Results:

• The V_E/[LA] ratio exhibited three distinct phases during incremental exercise.
• A decrease in V_E/[LA] correlated with increased [LA] and subsequent drops in blood pH.
• Blood pH regulation varied among subjects, with better regulation observed in those with higher Onset of Blood Lactate Accumulation (OBLA).

Conclusions:

• Respiratory compensation of lactate acidosis is more successful in individuals with higher endurance (higher OBLA).
• Effective pH regulation is observed primarily during slight increases in [LA] or mild acidosis.
• Individual differences in endurance capacity influence the success of blood pH regulation during exercise.