Why does one get cramps after sudden physical activity?

The correct answer is The build-up of lactic acid in our muscles during sudden activity causes cramps.

Key Points

• Anaerobic respiration:
  • During heavy physical exercise, most of the energy in our muscles is provided by oxygen breakdown.
  • Anaerobic respiration in muscles provides only some extra energy which is needed under the conditions of heavy physical activities.
  • The anaerobic respiration by muscles brings about a partial breakdown of glucose to form lactic acid. 
  • The accumulation of lactic acid in the muscles causes muscle cramps. 
  • Thus, muscle cramps occur due to the accumulation of lactic acid in muscles when the muscles respire anaerobically while doing hard physical exercise.
  • We can get relief from cramps in muscles caused by heavy exercise by taking a hot water bath or massage. 
  • A hot water bath improves the circulation of blood in the muscles. 
  • Due to improved blood flow, the supply of oxygen to the muscles increases. 
  • This oxygen breaks down lactic acid accumulated in muscles into carbon dioxide and water, and hence gives us relief from cramps.