Why are cramps caused in our muscle during sudden activity?

i. During sudden activities, our muscles lack oxygen.

ii. Due to the lack of oxygen anaerobic respiration takes place.

iii. As a result of lack of oxygen, when pyruvate of the muscle cells breakdown, it results in the formation of lactic acid which is a 3 carbon molecule with energy.

iv. This lactic acid accumulates and causes muscle fatigue and soreness.

v. In this way the presence of lactic acid causes cramps in the muscles.