There has been a clear misconception by a lot of gym-goers and non gym-goers alike about the function of the belt. Seems that the common belief is that the belt is used it is to support the back.
I’m sorry boys and girls, the belt is there not to support your back per se BUT instead, it helps you to increase intra-abdominal pressure. This increase in intra-abdominal pressure then acts as a brace to support and strengthen your spine.
So you would need to take a large breath of air into your belly – not your stomach – and try to exhale forcefully with a closed throat. It’s not breathing in through your chest. It’s in to the tummy. That is called the Valsalva maneuver. This act pushes out your belly into the belt which increases the pressure around your middle. You would need to learn it in order to use your belt effectively.
Imagine a solid tree trunk – it’s large and can handle a lot of weight because of it’s volume. A skinny branch is much more easily broken. The belt helps you to further increase the pressure in your midsection
Personally i would wear the belt closer to my heavier loads but that’s a personal preference. Some suggest to start wearing the belt earlier so as to make the Valsalva a habit. It is definitely a practiced habit
Reference:
Effects of abdominal belts on intra-abdominal pressure, intra-muscular pressure in the erector spinae muscles and myoelectrical activities of trunk muscles.
http://www.ncbi.nlm.nih.gov/pubmed/10619094