Accumulation of which one of the following in the muscles of sprinters leads to cramp?

During high-intensity activities like sprinting, the body's demand for energy exceeds the oxygen supply available to the muscles. This triggers anaerobic respiration, where glucose is broken down into pyruvate and subsequently converted into lactic acid [1]. While aerobic respiration completely breaks down glucose into carbon dioxide and water in the presence of oxygen, the anaerobic pathway occurs in the cytoplasm when oxygen is lacking [1]. The accumulation of lactic acid in the muscle cells leads to a burning sensation and muscle cramps [1]. This buildup acts as a temporary metabolic byproduct during sudden, strenuous activity [1]. While some modern research suggests multiple factors contribute to fatigue, the classical biological explanation for muscle cramps during short bursts of maximal effort remains the rapid accumulation of lactic acid and the resulting increase in muscle acidity [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.5 > p. 88