During intense running, muscle cells may not get enough oxygen to meet the energy demand. As a result, they switch from aerobic respiration to anaerobic respiration.
In anaerobic respiration:
- Glucose is broken down without oxygen, producing less energy.
- It leads to the formation of lactic acid, which accumulates in muscles and causes cramps and pain.
Glucose {\overset{\text{Cytoplasm}}{\longrightarrow}} Pyruvate {\overset{\text{Muscle Cell}}{\longrightarrow}} Lactic acid + Energy
