I don't know what happened but in the past 24 hours I seem to see this thing about training to do 100 pushups everywhere. How did this start? Why does everything think this is a great idea? So here's my PSA for the day: STOP IT.
For one thing, it's a very unbalanced training regimen. If you aren't throwing some rows, lat pull-downs, or pull-downs in there are on a regular basis you're setting yourself up for really buff chest and tricep muscles and little weakling back and bicep ones. While I think that's silly on an aesthetic level, apparently such imbalance also puts strain on your joints and can cause injury.
Also, what is the effing point of getting really really good at one upper body exercise? The only thing you're going to get good at is doing pushups. The second you try to do anything else with your upper body you're going to either fail or be in incredible pain the next day because it used one of the muscles not worked by pushups. There's a reason there's dozens of different versions of pushups, pullups, squats, and lunges. Changing the position of your limbs slightly when you do these exercises works the muscle in a different way or focuses on a different muscle. If the goal is to develop overall upper body strength, you need to do a variety of strength exercises, with (oh yeah) balance. If the goal is just to get really really really good at one pointless exercise, I'm just confused.
So I'm going to go for a swim. If I can't convince you that the 100 pushups thing is dumb, please throw in a few reps of seated rows in there now and again kthnx!