Most people do pushups without paying attention to tempo, but it completely changes what you get out of the exercise. A pushup has four phases: lowering yourself down (eccentric), the bottom, pushing up (concentric), and the top, or plank position. How long you spend in each phase determines whether you build endurance, strength, or power. For endurance, move quickly, about one second down and one second up with no pause. For strength, slow it down, pause briefly at the bottom, and then push up

Why American Education Declines Every Decade