It's not a criticism of the game to say that all of its design elements aren't conducive to a good workout. Novice players will move their arms much more than they have to. As you get better at the game you will probably learn to move your arms less.

This is my point. Playing better tends to result in exercising less. Saying you'll just play suboptimally to get more exercise is counterintuitive and will probably not work as it will force you to ignore all of the feedback that the game gives you, e.g. score and missing blocks.