Lactic acid

Lactic acid is a substance produced in muscles during intense exercise when oxygen levels are low. When your body works hard and can’t get enough oxygen to break down glucose completely for energy, it switches to a less efficient process that creates lactic acid as a byproduct. This build-up can cause muscle fatigue and a burning sensation. Lactic acid is also found in certain foods like yogurt and sourdough bread. It plays a role in energy production and can be removed by the body afterward, typically once oxygen levels return to normal.