Incorporate Your Whole Body
One of the easiest ways to increase your forehand's power is to incorporate your whole body into your swing. As strong as your arms are, I can guarentee your legs and core are stronger, and if you can bring these elements into your motion, you can greatly increase your forehand's power. To get your core and legs into your swing, you have to keep a bend at your knees and get a good "shoulder turn" for your core. At contact, it should feel almost as if your body is uncoiling, as you put all your weight into the shot.
Along with this, you may be trying to incorporate your body, but failing to transfer the body's power into racquet-head speed. If you're attempting to uncoil, you need to make sure that each body segment's "uncoiling" sets off the next, culminating in the whipping up and forward motion of the racquet head.
Loosen Up Your Motion
When playing tennis, some people tend to forget that the tennis ball ways in at around 2 ounces, with the average racquet weighing in at around 11 ounces. What does this mean? It means that if you get your muscles all tensed up you'll be better prepared to move your 300lb TV than you will be to hit a 2 ounce tennis ball. So, don't try to muscle the tennis ball, instead, hit with a loose, quick motion. The speed of the racquet head has a far greater effect on power than how hard your overall swing is.
Maintain a Proper Contact Point
No matter how quick your racquet speed or how well you incorporate your body, if your contact point is off, your forehand is more likely to be a weak looper than a powerful stroke. You should always remember to make contact with the tennis ball in front of your body. I cannot stress how important this is to adding power, and improving your tennis game in general.
Increase Your Backswing
Another easy fix to add more power to your forehand is to increase your backswing. Quite simply, the longer your backswing, the more time the racquet has to build up speed, which translates into more power for your shot.
Hopefully these tips will help you add more power into your tennis game.
