As it is in real life, each of these various gyms contains different equipment and workout options.
Certain gyms in certain areas will cover certain aspects, which will alter your players abilities to be able to certain things. Just like real life, if you pump irons all day long, before no time you’ll be a macho tank who can’t touch his crotch.
Here’s your guide as to which gym does what
Los Santos – Working out; Stationary bike, treadmill, etc.
If things like this are excercised often, you will have greater stamina and be able to endure things for longer. Running, holding breath under water, etc.
San Fierro – The more dojo style gym where you learn new fighting manoeuvres
Keep working at the fighting and you’ll get yourself out of a hand on hand battle easier. It’s that simple!
Las Venturas gym is a ratty dive of a place where you can learn some of the dirty stuff.
I’m not quite sure what they mean by this. I could speculate, but we’re not a rumour mill.
Other things that have been confirmed is the ability to being able to lock on to opponents (think Manhunt) and being able to block incoming attacks. It even mentions holding in a second button for “advanced blows and combos”.