what is the most a human being will ever be able to lift

Well if I had to think, your adrenaline rush would have to be on for you to use your maximum effort to lift something. Like say something like if your family was in a car and you were out of it and the tree stumbles down on the car. You would be able to lift it (just to get it off the car, not like above you) because of the adrenaline but it's hard to tell how much you can lift like adding up all the tons. I'm sure a person who studied Math at a university/college would give you a good answer.