All of us have experienced muscular fatigue after strenuous physical activity. When the body has plenty of oxygen, glucose breaks down through an aerobic pathway for energy production, called glycolysis. During intense exercise, oxygen availability decreases in the muscles, and anaerobic energy production is utilized. This process is known as “Cori Cycle”, in which lactate is produced.
For many years, lactate (or its protonated form: lactic acid) was unfairly considered as a waste product of glycolysis, which decreases cellular pH and leads to acidosis and pain in muscles. Several studies have shown there is no biochemical evidence to this issue. In fact, acidosis is caused by ATP, during the process of supplying muscle energy. So lactate production retards the acidosis to slow down the muscle fatigue. Also, muscle soreness felt in the following days after high intensity exercise is not related to lactate and is a result of micro tears in your muscle.