Normal resting pulse of adults is 60-100 beats per minutes. If it is more than 100 then condition is called tachycardia and if it is below 60 then it is called bradycardia. Your pulse of 57 can be bradycardia but if you are not having any problems like vertigo, dizziness and fainting etc then its fine. This can also be fine for those people who have inherited this. Well trained athletes also can have low pulse rate.