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Lactate Threshold

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Lactic acid; Metabolism; Physical fitness


The purpose of this paper is to review the delicate metabolic balance an endurance athlete must maintain to achieve a desirable performance. The optimum pace is ultimately determined by the athlete's ability to deliver large volumes of oxygen to the working muscles while simultaneously preventing excessive lactate accumulation in the tissues and blood.

Lactic acid has been associated with fatigue for nearly 80 years. This anaerobic metabolic by-product plays an important role in fatigue; however, many of the accusations concerning lactate's role in causing fatigue are unfounded or exaggerated. Its negative reputation is the result of an inadequate understanding of lactate kinetics during exercise.

Lactic acid is a naturally occurring product of anaerobic metabolism. It is not bad or an undesirable substance; in fact, it is useful as an energy source, as a temporary pyruvate reservoir and as a means of preventing the body's pH from falling to dangerously low levels.

The lactate threshold is defined as the highest metabolic rate obtainable while keeping the blood lactate at a steady state. At this level of intensity, the body is clearing lactate as rapidly as it is produced. Should the intensity increase beyond this critical point, lactate production exceeds removal rate causing a rapid increase in lactate accumulation.

For athletes to reach their greatest endurance potential, they must train their bodies to process lactate efficiently. This "fine tuning" allows them to compete at the highest possible intensity while maintaining relatively low concentrations of lactic acid.

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