Question

when sportsman run. he get muscle cramps. give reason

Answer 1

due to the anaerobic respiration which makes lactic acid in the muscles causing cramps.

Answer 2

When a sports man runs his muscles do a lot of exercise.As the oxygen available is not sufficient to power the muscles anaerobic rsspiration starts in our muscle cells and the following reaction takes place.
Glucose --------> Lactic acid + CO2 + H2O
When this lactic acid accumulates in the muscles it causes muscle cramps.