Sorry to ride the little off-topic train here, but I personally dropped PR squatting since I primarily began MT/KB'ing. I do ridiculous amounts of body weight squats and loads and loads of no-weight leg press, and this still allows me to train at close to 100% (as well as running etc).
I know that chasing numbers is such a great feeling, but if you really can't train properly for 4 days due to DOMS, and you primarily want to fight (not powerlift), you should probably try and change up the way you're training. I still strength train all my other body parts, because I can deal with the other muscle stiffness. But legs.... Man without legs I can't do anything.
Also, your body gets very used to the way you train. If your diet is in check, I'm sure that adding an extra leg day every week (preferably when you're not 30 days out from a fight), will help your body adapt to the workouts. (maybe a day of just 75% leg lifts).
Either way, there is no real... "proven", methods. Only what you can learn from your own body really.
One thing I'd like to touch on is the idea of 400/800metre SPRINTS... You shouldn't be sprinting this (at least not just straight off the bat). You can run it at a high speed or intensity, but to push your muscles this much ISN'T as good as most people would think (not to mention the strain it has on your muscles, especially 30 days out of a fight).
It sounds like not much at first, but 400metres of sprinting? Are you only going to do 2 sprints and be done? I for one used to be exactly the same in that mindset of, "I can do anything if I put my mind to it", but lately I've shifted more towards smarter training rather than harder. Don't get me wrong, it's a great GOAL to have, but not a great thing to just dive into, I'll explain:
An exceptionally fast runner can sprint the 100metre in 10 seconds. So, if they could keep up a 100metre sprint pace for 400metres, they'd run it in 40 seconds. But that's unreasonable. If we give them 55-60 seconds, that's more reasonable. Now take a group of people who don't train solely for sprinting/running (majority of people) and we can generally "sprint" 400metres in probably around 80-90seconds. Our body's aren't made to sprint to that extent, and if you need to sprint for 1minute 30seconds out of 2/3 minute rounds, you are definitely not conserving your energy properly for the fight.
I'm not trying to sway you from pushing your limits, but rather I'm trying to express that there is a smart way to train. First time I ran properly, years ago, I did 7.5km and couldn't walk for a week and a half. If I paced myself at 1km, then 1.5km, and progressed, I would've never had problems, would've never swayed me from the idea of running and would've loved achieving the small set goals.
I know you want to push yourself, but sometimes it's better to train smart rather than just hard, especially if you're only 30 days out from the fight! Don't hurt your ankle sprinting 3 weeks out from the fight, just because you were too tired to run with proper form and you were too set on sprinting 400metres
.
Just go for timed jogs and try and beat the time tomorrow! This will push yourself more than you think.
tl;dr
If you want to push yourself, go for a 5km jog, time yourself, and see if you can beat it tomorrow. Don't just dive into the deep end because you've seen a pro do it. You're 30 days out, don't do anything too dramatic that will injure yourself.
