Day 18: Lactic acid causes fatigue, muscle burning and soreness - Myth or Fact? #lacticacid

In the 1920s, Nobel Prize winners A.V. Hill and Otto Meyerhof discovered that lactic acid is produced during intense muscle contractions when oxygen is scarce. However, there has never been direct experimental evidence linking lactate to fatigue. Over time, false correlations between oxygen deficiency, lactic acid, and exhaustion were drawn from these observations, and they still persist today.

In reality, other metabolites, like potassium ions, hydrogen ions, and components of ATP (such as ADP and phosphate), also increase during intense exercise alongside lactate. These metabolites interfere with cellular processes, contributing to fatigue.

Because lactate often rises with these other factors, and due to its ease of measurement, scientists use blood lactate primarily as an indirect marker of acidosis and fatigue, rather than a direct cause of exhaustion.