Okay so, this is kind of a disgusting question... sorry about that in advance, guys. Say you are super strong, super fast, and super durable. There is a not so strong, fast, or durable normal human standing within punching range, and you are a murderous sort and want to punch them. But not just punch them, your goal is to punch through them and connect your fist with their spine (aka put your fist nearly all the way through their body. Gross.)
Let's say this normal human is a male of around average height, weight, and build. You are about 6 ft tall with what appears a healthy human physique (aka you may look muscular, but not appear extraordinarily fat). In actuality, though, you are denser and may weigh up to twice as much as an average human of your height and build (I suppose I am saying you may possess up to twice the mass?)
If I understand this correctly, how hard a punch hits is determined by your fist's momentum, or the combination between mass and velocity. So my question is: What acceleration would you need to achieve during your attack in order to impart enough force to punch your fist into a human body? What happens to you if you do this? (By this I don't mean injury, as I've stated you are extremely durable. I am asking if punching with this much force would throw you off your feet/balance, etc.)
If it's necessary, you can be wearing heavy armor on your arm and/or body to increase your overall weight; you are strong enough it won't slow you down.