Lactate concentration in plasma and red blood cells during incremental exercise

Area of Science:

• Exercise Physiology
• Biochemistry
• Sports Science

Background:

• Lactate accumulation is a key indicator of metabolic stress during exercise.
• Understanding lactate distribution between plasma and red blood cells (RBCs) is crucial for interpreting exercise performance and fatigue.
• Previous methods may not accurately capture rapid lactate shifts due to exchange between compartments.

Purpose of the Study:

• To investigate the dynamic distribution of lactate in plasma versus RBCs within capillary blood.
• To quantify changes in the RBC/plasma lactate ratio during and after incremental exercise.
• To elucidate the kinetics of lactate movement between plasma and RBCs under exercise stress.

Main Methods:

• Employed a novel rapid plasma separation technique to minimize lactate exchange.
• Measured capillary plasma lactate and whole blood lactate concentrations in 10 subjects.
• Calculated red blood cell (RBC) lactate concentrations during incremental treadmill running and recovery.

Main Results:

• The RBC/plasma lactate ratio significantly decreased from pre-exercise (1.0) to post-exercise (0.37) levels.
• Capillary plasma lactate increased substantially more than intracellular RBC lactate during exercise.
• During early recovery, RBC lactate initially rose while plasma lactate declined, with both decreasing later.

Conclusions:

• Plasma lactate accumulation significantly outpaces RBC lactate during incremental exercise.
• Lactate distribution dynamics shift markedly from rest to exhaustive exercise.
• The RBC/plasma lactate ratio and concentration gradient stabilize during later recovery phases.