Higher-than-normal lactic acid levels can lead to a condition called lactic acidosis. If it’s severe enough, it can upset your body’s pH balance, which indicates the level of acid in your blood. Lactic acidosis can lead to these symptoms: muscle weakness.

The similarity is that they both happen under anaerobic conditions and produce a little amount of ATP. The difference is that alcoholic fermentation gives CO2 while lactic acid does not.

Lactic acid fermentation converts the 3-carbon pyruvate to the 3-carbon lactic acid (C3H6O3) (see figure below) and regenerates NAD+ in the process, allowing glycolysis to continue to make ATP in low-oxygen conditions.

Lactic acid fermentation has two steps: glycolysis and NADH regeneration.

Lactic acid levels get higher when strenuous exercise or other conditions—such as heart failure, a severe infection (sepsis), or shock—lower the flow of blood and oxygen throughout the body.

Treatment of elevated lactate levels should be determined by the underlying cause. If hypoperfusion or hypoxemia is the culprit, focus on improving perfusion to the affected tissues. In shock, treatments include fluid administration, vasopressors, or inotropes.

A high lactate level in the blood means that the disease or condition a person has is causing lactate to accumulate. In general, a greater increase in lactate means a greater severity of the condition. When associated with lack of oxygen, an increase in lactate can indicate that organs are not functioning properly.

Lactate is the output of the anaerobic system; after that it performs its most important function. It is the main fuel for the aerobic system during competition and much of training.

When the body has plenty of oxygen, pyruvate is shuttled to an aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown—and thus energy production—to continue.

As exercise intensity increases there comes a break point where blood lactate levels will start to rise (production starts to exceed clearance). This is often referred to as the lactate threshold (LT). If exercise intensity continues to increase a second and often more obvious increase in lactate accumulation is seen.

Muscles are producing lactate even at rest, usually about 0.8-1.5 mmol/L. Although the lactate threshold is defined as the point when lactic acid starts to accumulate, some testers approximate this by crossing the lactate threshold and using the point at which lactate reaches a concentration of 4 mmol/L of lactate.

The accumulation of blood lactate will hinder your muscles’ ability to contract, and you will be forced to slow down or stop. If the pace you can hold at your lactate threshold is higher than the pace your competitor can hold at his or her lactate threshold, you go faster, reach the finish first, and win.