Why is it that having your arms connected to your body in the golf swing results in less power than a longer swing without arms connected?

Trying to switch to a shorter compact swing with my first golf lesson today resulted in afterwards a loss of 5 mph of clubhead speed at least with a much lower ball flight


yes it is true. when you swing without your body, your arms, of course, move faster. BUT when you swing with your body, which meaning, your body moves and your arms stay connected to your body, you lose a bit of swing speed. Do you know why? because your body moves slower than your hand. So.... this is what Pros practice all the time..... faster hip at downswing. it took me 6 months to practice this sequence. When you do that, you will gain at least 10 mph than before.