Question

Muscle strain and soreness is more likely if you....

Answer 1

when you don't exercise enough, don't exercise at all  or if you just don't exercise properly. This is because the muscles need training and if they are not used in a while, then will get the idea that they are not needed. that is why, when exercising, the body needs to be pumped up so that the muscles are too.   

Answer 2

if you exercise or are active without stretching before hand