Is it safe from structural point of view to exercise on a treadmill on 2nd floor (wooden) of my home?

Answer 1

Yes - should be perfectly safe to do so unless the floorboards have some sort of insect infestation or are otherwise rotting.

Buildings have a standard safety factor of 10 and upwards meaning if a floor is likely to have a load of 500kg on it then it will be built to take a load of 5,000kg.

Answer 2

I gather it would depend on how heavy you are and if your weight would break the floor boards, as long as you dont weigh like 200kg or more it should be perfectly safe.