1. Pump Some Iron
One way to prevent knee injuries while bowling is to build your leg muscles, especially in your thighs. This gives your approach more control and balance, so your knee tendons and ligaments deal with much less strain. To do this, visit your local gym and try out the Nautilus machines. The Hip Extension Bench is just one of the machines that your gym may have. All of the upper leg strengthening machines work great for toning those muscles you need for the proper approach and release of your ball. You might also want to start a walking program, starting light and increasing your distance and speed as you progress. This also will build leg muscles. Avoid hills during your walking workouts, especially if you have or previously have had a knee injury.
2. Brace Yourself
Wearing a knee brace while your bowling is another to prevent knee injuries. While this is not a substitute for building the leg and thigh muscles, it can keep you in the game during an injury and serve as some protection while you heal from this injury. Choose a brace that fits comfortably that your doctor or physical therapist recommends. Many PT professionals recommend knee supports, or "sleeves" as they are sometimes called, for things such as minor strains, sprains or inflammation. While they may recommend an actual knee brace, which temporarily immobilizes the knee pre and post operatively. You want your PT professional to fit this brace for you so it does the good it's supposed to.
3. Live Well
You may not think of getting three square meals and exercise three times a week as a way to prevent knee injuries while bowling, but it does help. Getting proper nutrients helps your body's ability to rebuild cartilage and muscle. You may even try adding a Glucosamine and Chondroitin supplement. Just be sure you are getting a high quality product that has been "standardized," an extra testing step that is not required by the FDA, but ensures you are getting what you paid for. Daily exercise, or at least a walk 3 times a week for about 30 minutes, can keep the extra weight off, which really takes its toll on the joints. Try incorporating your cardio workout with your muscle building workout by hopping on the treadmill for 20 minutes or so before your leg work, then again for another 5 to 10 minutes of cool down.
