Contraction of muscles, we all know that's key. And it's the fast twitch we all strive for. But it's difficult trying to isolate a fast contraction in, say, your triceps, at least in punching movement. If you stand and are ready to punch, try concentrating on contracting your tricep - it's almost impossible to do.
Sure, you can do a weight training method with a tricep exercise, but it's not going to help with punching as much as you might think. It's also kind of dangerous to do the standard triceps weight exercises really fast.
What's key is contracting the muscles in your core, and the muscles of your body together as a unit. It helps them fire quicker. It helps in that split second your decide to throw that punch at that opening....by the time you think it, that punch of yours should already be returning as another one is already being thrown.
Trained with some top lever strikers. Used to do "flinch/flex exercises. Just strolling across the gym and flinching your core like your friend walking by you was going to give you a shot in the stomach you weren't ready for. At the same time you're flinching your core you do it with your grip, your hips, your legs, your back, your elbows slamming against your ribs. Just one massive contraction to your whole body for just a split second and relax immediately.
It can do wonders for your fast twitch and your punching.
The best weight exercise I've done for fast twitch punching is a bench press, but in a specific way, not the standard. And it's not for beginners who are just using weights for a little bit. Say your max bench is 250 pounds, say you can do 185 easy and often....lets just use those numbers for the sake of using something.
Throw a 45 on each end of the bar, so you have 135 lbs. Assume the bench position, bench it, lower it quickly and as you bench it - let it go at the top so the bar leaves your hands. Just an inch or so, catch it, allowing the weight to blast your arms downward [it's won't be heavy or hard to manage using the max numbers we used] but barely let it touch your chest, as opposed to bouncing it off your chest, and blast it skywards again, this time letting it go three or four inches out of your hands. Repeat. It sounds like it could be dangerous but we did them for years and years and never had any problems, accidents or mis-steps. [Just keep beginners out of the equation] They give great blasting power and speed with the extension of the arms. [but arm extension isn't exactly punching] Gives good fast twitch payoffs for the extension of your arms. Always have a trainer there. And don't friken kill yourself.