There are many types of weight training belts on the market today designed to help protect the lower back during heavy lifting. The most common belt is wide in the back and narrow in the front. To most, this looks like a good design but it has it's flaws:

1) The purpose of a belt is to increase intra-abdominal pressure (IAP) which gives support to the spine. Looking at the traditional wide in the back design it is easy to see where this falls short. You must have some width in the front to increase IAP.

2) Ideally, the belt should be the same width in the front as in the back (about 4-6 inches). This type of belt can press into the sides so choose a belt that is cut down the sides without changing front or back size.

Even if fitted correctly, a belt should not be used on all exercises. Using the belt too often can lead to weak abdominals and ultimately a weaker lower back. These muscles learn to rely on the belt as a aid instead of promoting strength as you progress through your lifting program.

It's best to use belts on exercises that involve heavy weight and those that place undue stress on the lower back. Examples are deadlifts, bent over rows and squats. Use the belt for heavy sets on these exercises and don't rely on it for lighter sets.

Some trainers feel that a belt should never be used. The stress that if an exercise is perfomed correctly, in good form, the chance for injury should be eliminated. Unfortunately, not everyone uses perfect technique all the time, and a properly chosen belt is an effective safety precaution when performing certain heavy lifting exercises.
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Dr Lanny Schaffer is an Exercise Physiologist and the President of The International Fitness Academy. For more cutting edge health and fitness information go to http://www.aerobic-exercise-coach.com