During heavy exercise, we get cramps in the legs due to the accumulation of

During intense exercise, muscles need more oxygen than blood can supply. Without enough oxygen, muscles produce lactic acid as a waste product during energy production.

When lactic acid builds up in muscle tissue, it causes pain and cramping. This burning sensation makes muscles feel tired and forces you to slow down.

Lactic acid accumulation is the main cause of exercise cramps. Once you rest, blood flow removes the lactic acid and the cramping stops.