Factors Influencing Blood Lactate Concentration During Exercise: A Narrative Review With a Lactate Shuttle Perspective

ABSTRACT Aim Blood lactate concentration ([La − ]), usually measured in mmol/L, is one of the most frequently measured parameters during clinical exercise tests as well as during performance assessments of athletes. Therefore, the purpose of this review is to examine the methodological and biological factors that influence [La − ] in order to improve the accuracy and interpretation of its measurement during clinical, research, and athletic testing. Methods A narrative review of the scientific literature was conducted, focusing on studies addressing the biological as well as methodological variables that may affect the measurement of [La − ]. Results According to the lactate shuttle theory, blood [La − ] depends on production, transport, and consumption. Both methodological and biological factors can substantially alter these processes and, subsequently, [La − ], potentially leading to misinterpretation when comparing data across sessions or individuals. Conclusion Since lactate is commonly measured in research, medical, and training testing, it is important to understand these factors to avoid misinterpretation. The main recommendation is to control all these factors when measuring [La − ] and to carry out the measurements under the same conditions when monitoring the evolution of a specific person or comparing different individuals.