How do you train for these massive downhill marathons

Maybe running downhill a little bit more?

20x400 downhill

Rocker soled shoes are the way to go for a downhill course. When I ran the second downhill leg at Hood to Coast, I tested several shoes on downhill running and the Hoka won hands down. However, lots of brands make rocker soles now so it wouldn't need to be Hokas. Basically, the rocker heel turns the downhill impact into more of a rolling motion than the "slap" of a normal shoe. At Hood to Coast, I ran 30sec/mile faster than my goal pace and had no leg soreness at all afterwards.

I would test my mental toughness and ask why you need to cheat to claim a PB.

Running to downhill more its helps you.

It’s also important to learn proper downhill form.

The body handles it best if you’ve leaned downhill form (hips forward and upper body tilt, not braking on your heels) and run downhill enough to develop the quads. You can look up downhill training plans on the Internet and just look for runs that say downhill. Add that frequency and duration of downhill running to your training plan.

I ran one of these types of marathons, and the most important thing is practicing running downhill and running downhill fast. I did a lot of workouts where I would run downhill at marathon pace or faster. I did some specific quad strengthening work, too. If you run them correctly, these downhill races are going to be faster than a flat course. No surprises there. However, I think a lot of people think these races are going to be a slam dunk PR race and blow up spectacularly because they do beat up your legs differently and more severly in some ways than a flat marathon would. They require specific training, but if you do that, you can run pretty fast.

Fisky is the king of drawing definitive conclusions from unblinded n=1 studies where the researcher is the subject.

A buddy of mine did one of the Revel Marathons and crushed his previous PR. He didn't have access to long downhills, nor did he have a treadmill that could be adjusted down. Working with what he had, he started off with downhill strides for several weeks, and progressed to throwing on one of those weighted vest and gradually doing 200Mto 400M downhills sprints several times a week, and after long runs. It seemed to work for him. He also did a lot of running specific leg strength.

I think 40 mile long runs around a flat parking lot will be best.

This. And make sure you ABSOLUTELY DO NOT run faster than 9-10 min/mi at any point

So his previous PR was on a downhill course? Otherwise no, he set a downhill PR. Check Strava GAP pace to see the real effort

Try the Steamboat marathon and see how you walk the next day, tough guy. Starts at 9500 ft, drops immediately to 8000 feet in first 4 miles then goes up and down for the next 22 miles into town @ 7000 feet. Your quads are mush at mile 4 and then rolling hills after. No one gets PRs. ....Try an hour slower than PR.

Course Records
Marathon
Male: Christopher Prior 2:23:59

Just imagine how fast this guy would be on a flat course /s

-3kft over 26.2 is just over -2% grade - that'll feel pretty normal if it's evenly spread out. If you have a >1mi section with a grade steeper than -4-5%, then do downhill strides after workouts a few times throughout the block.

Some of those course have uphill sections in them too. Hilly long runs & hill workouts. I like hill workouts where you take a 1:30-3:00 hill & run up at threshold effort, maybe jog :30-1:00 at the top, turn around and head back down at something like marathon effort. Practice running fast/efficient up & down a hill. Something like 8-12 reps. Can sandwich it between tempo work: 2 mi tempo-8x1:30 uphill/:30 jog/marathon pace down/2 mi tempo. Something like that.

I put bricks on the back of my treadmill to simulate a 4 to 5 percent downhill grade. once a week I would do a tempo run and a marathon paced run. Besides building up specific muscles, I learned good downhill running form. also did squats and lunges almost every day to build up my quads. Super shoes seemed to help too.

How does having them on the treadmill simulate downhill running?