Lactic acid
An acid produced during exercise due to the breakdown of glucose when there is a limited supply of oxygen, meaning it is not broken down completely. During certain exercise there can be a lack of oxygen, due to anaerobic respiration. Lactic acid then accumulates in the bloodstream and tissue and produces hydrogen as it dissolves, thus contributing to muscle fatigue. When more oxygen is supplied through higher intensity exercise the lactic acid is broken down and more energy is created.
