Question

If we eat curd which contains lactic acid why do we not get pain in the muscles

Answer 1

Curd contains lactic acid but it isn't accumulated in the muscles. This lactic acid that we get from curd enters our digestive system (alimentary canal) and our body absorbs the required nutrients from it which is very much beneficial.

Whereas when we exercise a lot "Anaerobic respiration" takes place in our muscles of limbs (usually legs) in order to provide more energy during which, lactic acid is formed as the end product. This gets accumulated in the muscles, giving rise to cramps.

Hope this helps you