Why can I barely do one push up, yet I am otherwise relatively fit and eat healthily?
This has nothing to do with your wrists and hands, or you back either. The reason that people are often unable to do the push-up exercise with any facility is simply that this is a movement most people don’t do very often.
The pushup uses the big muscles of the chest, the pectorals, and the extenders of the forearms, the triceps. The front part of the deltoid (shoulder) gets a little work.
So… How often do you push something heavy? If you worked in an old-time coal mine, you might get quite a bit of work pushing carts full of coal… Or if you were a stevedore pushing heavy crates and boxes around. But in modern life, we don’t often use these muscles much.
However, these are big muscles and they tend to “train” easily. Raw recruits in the army often go from only being able to do a few pushups to being able to knock out 50–60–100 by the time they are out of basic training.
Start out with “wall” pushups….Lean towards a wall and push yourself away 10–20 times. You should feel this in your chest. As that gets easy, increase the angle of your lean…. Eventually go to a piece of furniture like the back of your sofa. You’re progressively moving more and more of your body weight. You should be able to work up to doing regular pushups with some easy in a few weeks.