What Ultra?
Back in 2004 I did IM Cour Dalene in 12 hrs. So I thought I could do a technical 20 miler, over 7k ft climbin and about 9k decsent (Bridger Ridge Run) I was destroyed. Quads shredded,
So yes you can do it but its very different.

If you mean the ultra will be flat.....You can do it

Ultra would be the Hennepin 100. I’ll be doing the 50 mile option.

What is your background with Ultras? How is your aerobic capacity and what kind of run volume are you doing? How is your recovery?

I say go for it. I couldn't find elevation information for the race, but I've done a run focus for the past few years to address it as a weakness and once I complete my A race Ironman events, I almost always run a few Ultras. I've done a 100 miler multiple times a month out from an Ironman without issue. Caveats being I'm not the fastest runner, but I have relatively large aerobic capacity from two decades of 20+ hour swim/bike weeks and since I've added running I realized that while my top end isn't crazy, I can go slow forever. I also recover decently well. I've never raced one of these Ultras in close proximity to an IM expecting the greatest results. Instead I pace myself slow and steady.

I'd say just give it a try and use it as a data collection exercise. Pace well and embrace the suffer!

I’ve done a handful of 50 milers before I started triathlon 5 years ago. Since then I’ve just been triathlon focused and have done 5 140.6. Looking to mix things up a bit this year. I tend to peak at about 50 miles a week running during IM training. During your IM prep were you doing back to back long run days to prep for the 100?

I have done it twice. Not with a 50 miler but once with a hilly 50K and this past year 5 weeks after IMMD I did a 55k. Both went well, last was even better than I had hoped for. Good luck

Go for it.

As it's not your first 50, you have a fair idea of your capabilities and what you're signing up for. Muscle memory and some race smarts and experience goes a long way in ultras.

You may well have a very good run at the 50. Conversely, what's the worst that can happen? A bad day where you shuffle and walk home the last 20 miles? No big deal, it's just a long day and miles in the bank. Even with a focused prep and training, that happens to most ultra runners at some point.

4 weeks after IM isn't an unreasonable recovery period.

I did a 48 mile run with close to 14,000 ft of gain, about 4 weeks after an IM.

After the IM, I took one week off and then started back easy running again. Between the IM and my race, my longest run was probably a ten mile hike/run on a mountainous trail. Even with IM training, I've almost never ran over 17 miles with my longest runs but I do run consistently and enjoy doing back to back days with a ten miler one day and a 10-12 miler the next day. This seemed to be plenty to allow me to do the ultra race without any issues. It felt great so I hope you enjoy your race too

The first year I was not doing back to back days with a long run. Subsequent years as my running volume increased I was doing it. I had good results with both but better with higher volume.

Don't race the IM all out and it should be perfect to turn in decent times at both. Turn yourself inside out on the IM and you'll destroy yourself on that ultra.

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-Bryan Journey
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