Originally Posted by
Michael Wolf
Use it for your last warm-up and your work set(s). When you get stronger, you may want to use it for the last two warm-up sets.
The belt doesn't exactly "help your abs do their job by keeping your stomach/lower back tight." It facilitates a stronger abdominal contraction than can be achieved without the belt, thus training your abs harder and making them stronger. Similar to how you can get stronger by squatting against a loaded barbell, versus pretending there is 405 on your back and trying to replicate the movement and conditions of that scenario.
So belting your heavy sets makes the whole system, including your abs, stronger. As a result of that chronic adaptation, what do you think will happen to your unbelted lifts?