How To Increase Power On The Break
The arm has a limit when it comes to how strong it can be; arm strength is only a small part of the whole package when it comes to having a more powerful break in pool. Accuracy is the most important thing, and should be the first thing you work on when it comes to increasing power on the break. Get a hang of hitting the head ball on the rack with regularity, and once this is done then you can move on to getting more power.
Once your accuracy is where you need it to be, you can start to work on the power stroke by gently moving the cue back and forth, and when you make your break you must transfer your weight from your back foot to your bridge hand. This is where the power comes from. Many people will tell you that you should transfer your weight to your shooting hand, but the bridge hand is where the power comes from. The shooting hand is where your arm strength comes into play.
If you find your break going off, or if you lose control, back off and try it a little softer. Accuracy is the number one goal when it comes to the break. Do not go for it all at once. Slowly work on transferring your weight and building up the strength of your shot as you go. Trying to do too much at once will only bring frustration.
Building up break strength takes practice; hundreds and hundreds of breaks must be done before you become comfortable with your full shifting of weight. At first the transfer of weight will not be that large. Take it slow and let it come naturally, and soon you will have a powerful break that will spread the balls all over the table.