Lactic acid is mainly produced in muscle cells and red blood cells. It forms when the body breaks down carbohydrates to use for energy when oxygen levels are low. Times when your body's oxygen level might drop include: A test can be done to measure the amount of lactic acid in the blood. What is Lactate? Lactate is a bi-product constantly produced in the body during normal metabolism and exercise. It does not increase in concentration until the rate of lactate production exceeds the rate of lactate removal which is governed by a number of factors. A widely held misconception is that lactate is a toxic waste product of metabolism, driven by hypoxia and/or hypoperfusion. 1 It is now well established that increases in blood lactate due to hypoxia are likely the exception rather than the rule. 1 At physiological pH, lactic acid (C 3 H 5 O 3) is almost completely dissociated into lactate anion .