I've got a little problem with this. Do you count 1 rep when you go down and back up or count a rep when you down or up.
Just start with normal push up position, then go down, stay there 7s and next go up, and also stay there for 7s - guess one rep looks like this.
Yes, one rep is when you go up, hence PUSH UP. Just like Matthew said.
I meant one rep is when you go down and then you push up, you count it when you push up.