Why Does It Burn When Working Out – Lactic Acid Explained

Trainer FAQs 

A common question that I’m asked is “why is it burning?” When you weight train and do strenuous exercise, your muscles start to burn as a sign of fatigue. The burn comes from the accumulation of lactic acid.

     Lactic acid forms when pyruvate, your body’s main energy source, is broken down in the absence of enough oxygen (anaerobic exercise). The lactic acid will continue to accumulate until you let your muscles recover and get enough oxygen. You can typically workout at this type of intensity for 1-3 minutes. The more that builds up, the less your muscles will be able to do. As your stamina increases, lactic acid formation will accumulate slower. Lactic acid formation is normal and is your body’s natural defense mechanism to protect its own muscle system from over exertion.

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