Yeah that's the beauty of using a belt. And it purportedly makes your abs bigger too. It's a panacea for some. I have an article on the training board about a study showing the use of a belt allows you to train your legs better!
ahahahahahahahahahahahaha no.
^ya, abs contract harder, that's the claim
LBSS, standard dogma says it gives your abs something to push against and this works them harder. IDK, dont have a horse in this race, dont use a belt but that;s what they claim.
I have heard this but the way it was explained to me was the belt gives your abs something to push against which gives you immediate feedback and the ability to brace your core better. Not sure how this plays as far as making them bigger/stronger though.
Lol. This is funny. This is one of the half truths that has morphed into some myth. Physical pressure on a muscle increases activation. Best example I can think to explain activation is bench press. Take a kid who has never bench pressed. Ask him to flex his pecs and he will wiggle his shoulders. Now get him to bench press for a year. Ask him to flex his chest and his chest muscles will contract visibly. Is this proof that he is stronger. No. This is an improvement in muscle activation (given that he was a beginner and started benching he is most likely stronger even if the gains are mediated through neuromuscular activation rather than actual tissue adaption) but the point is improvement in activation does not equal strength.
Also, consider the kid after he has only been benching for 2 months. Ask him to flex his pecs. Maybe one side his chest moves slightly but he isn't all the way there yet. Now take your index finger and press firmly against his pec. Ask him to flex. He will be shocked at the contraction.
Your sensory cells (specifically pressure receptors) turn on in response to pressure and send a signal to the brain. While this signal is being sent we get a multiplicative effect of signals sent back toward the muscle. This IS useful. This is why coaches should put their hand on athletes and good coaches use this trick a lot - putting your hands on someones hipflexors during a march get them to actually fire - I have had athletes that are try to do a straight leg pull back and don't figure out how to use the hamstring to initiate it until I press on it.
So back to the argument at hand. Will a tight belt increase abdominal activation slightly? Maybe. If you didn't have the coordination to activate your abs this might help... But your trying to jump high without a belt. The goal is to learn to coordinate your abs and contract them without pressure - a belt can be a teaching tool - but it's not going to make your abs bigger! In fact if anything it is a crutch that you will rely on and you won't learn to contract your abs without pressure any more.
So, yes pressure applied to a muscle does increase activation. Great trick to learn how to activate muscles. Pressure and bands are great in every toolbox for this reason. But neither is very good for making muscles bigger.