I have finished three of each. Apples v Oranges. Ironman was definitely more difficult and took longer to recover. May have a different answer for you if I were closer to the point-end of each field (I am a BOP Ironman and MOP 50-miler).

Speaking as someone that has done neither but wants to do both, I wonder if the 50 miler would be better compared to the HIM and the 100 miler to the IM. Since those are kind of the crowning achievements in each sport. I know there are some races that are longer than 100 miles but those seem to be more commonplace.

Just a thought.

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The best pace is a suicide pace, and today is a good day to die. -Steve Prefontaine

For me, right after each race, I feel like my legs took more of a beating during the 50, but my whole body was much more out of it after Ironman. I was completely with it after the 50 but not at all after Ironman. I do agree with the apples to oranges comparison...

100 milers are usually not like Ironmans. An incredibly fast time for a 100 miler is about the same as a really slow time for an Ironman. And the pain in your running muscles really starts to add up instead of being spread out more like in an ironman.

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Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
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As someone that has decided not to do either, my take is:

Racing an ironman is SO MUCH HARDER than racing a 50 miler (going hard, close to your capabilities, fully trained).

Finishing an ironman is SO MUCH EASIER than finishing a 50 miler (out there to beat the cut-off or something like that).

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David Roche
Some Work, All Play podcast: https://podcasts.apple.com/...ll-play/id1521532868
Coaching: https://swaprunning.com/

I have done one of each, about 6 months apart. Running is my strength (1:23 13.1, 4:50 70.3 as my PRs).

Having done a handful of 50k's, a couple marathons, and a 5ish 70.3's. I did just over 8 hours for the 50 miler and 11:26 at Ironman Tahoe.

Without a doubt, the 50 mile run was the hardest physical event I have ever done.

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/kj

http://kjmcawesome.tumblr.com/

I have done 2 Ironmans (solidly MOP) and more marathons than I remember. Never done a 50 miler but have paced most of that distance for a very hard 100 miler in the Wasatch mountains of Utah, multiple times. In my experience I have a hard time comparing the 50 miler to an Ironman. Is a pure suffer-score I would put the Ironman way above the 50 miler. This is assuming similar conditions of elevation gain, wind and heat. Elevation and conditions can make all the difference but assuming those are similar I have to say that the Ironman is way harder. However, I would never compare an IM to a 100 miler. The IM is definitely harder than a 50 mile run but it is nowhere (NOWHERE) near as hard as a 100 miler.

I haven't done a 100 miler but I have intimate insight on what that effort does to a person and it is brutal. I personally have no desire to do a 100 miler after what I have seen it do to my friends. The suffer score for the IM is somewhere in between the 50 and 100 miler but much closer to the 50 miler than the 100 miler. To me IM is pretty much the most suffering I am willing to endure as a hobby. Anything beyond that is certifiably crazy stuff.

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http://dontletitdefeatyou.blogspot.com

I guess the intensity level that you hold is the big determining factor. I've done a bunch of Ironmans but never a 50 miler; 60K is my longest open run race. My last IM was Chattanooga @ 10hr58min...fell apart on the marathon and walked the last 3 miles or so for a 4:17 run split and felt totally fine the next day. For my 60K I ran every step for a 5:12 finish (8:25min/mile pace) and had trouble walking for 2 days.

Did my first 50 last year and plan on doing my first IM this year (Tahoe). While I've only done a half ironman, three months after the 50 miler, I must say the training for an Ironman is much more enjoyable. Definitely like a mix of swimming and cycling and not just running...mile after mile after mile.

I did similar but found the opposite to be true. Ran just over an 8 hour 50 miler (mostly trail) and went to a wedding that night. Had a disappointing 11:35 IM and was wrecked for a week. Everybody reacts so differently.

As far as recovery and effect on the body, I would rate racing a HIM as easier than a marathon. 50s and 100s are a different game again.

The extended time on feet, repetitive use of similar muscle groups and quite often terrain make 100 milers more physically demanding than IM.

I think the sweet spot of physical comparison between racing ultras and tris is Ironman and a flat road or track 100 km. Not only is there a similar degrees of "body trashing" and recovery, but also a close correlation with running pace. My PR run at IM and PR 100km pace are remarkably similar.

Interesting. For me, I did a 10:57 Ironman with a 3:29 run split and for the 50m I would say my effort was pretty similar, maybe a little less than ironman. Right after my legs hurt way more after the 50, but I was very very fuzzy after IM and felt fine after the 50.

I think you're distinction between racing and finishing is significant and you make a valid point. Many people underestimate how far they can swim, cycle or run if they back off the intensity and fuel adequately.

However I do think you are in for a rude shock when (if) you train for and race a few 50 milers.

I think what makes it so difficult to compare is the variability of terrain and topography that ultras present. Racing a flat 50 mile may take about the same time as a hilly, technical trail 50 km. At least Ironman is generally raced on relatively similar courses.

I had never thought to compare running 50 miles to doing an Ironman, although I've done both.

It took me 12 hours to run 50 miles. It was a race I put on with a bunch of friends, we just decided to run around the Rose Bowl in Pasadena, CA for 12 hours. It's a 3.1-mile loop and we did it on the shortest day of the year, Dec. 21. (We had made an earlier attempt at a 12-mile run on the fall solstice, and it was a really bad idea, because temps were over 100 for most of the day and I managed only 43 miles.

That was in 2003, I think. It would be five years before I tried an Ironman. I've done four now, and I would say that Ironman is much harder to train for, there's a lot more gear to think about, a destination to travel to - it's a very high stakes day. And I've never come close to my 50-mile time in an Ironman.

But a 50-miler? Heck, you can find one nearly every weekend in the L.A. area. Easy to get to, friendly low-key people for the most part.

I'd say Ironman wins in the difficulty department.

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Sharon McN
@IronCharo
#TeamZoot
Clif Bar Pace Team 2003-2018

Based on energy used and work done during the 2 races, you're def doing more work in an IM. Using myself at 6'2" and 176 lb as an example, calculations show that i'd burn around 9700 cal doing an IM, vs 6800 in a 50-miler. In theory then, the IM work is equiv to running about 71 miles, using my 136 cal/mi run figure. (Swim cal = 288 cal/1000 yd and bike = 44 cal/mi.) These numbers are calculated using the formulas found in this link, which mungub posted back in a Jan 2015 thread on cal burning during the swim:

http://www.eload.net/...-for-ironman-p136203

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."

With 3 50 milers (all at JFK 50) and 5 IM's - I rank the 50 as tougher. My finishing times in both have been similar with a 50 PR of about 10:20 and an IM PR of 10:50.

In my personal mindset, you get to lie down for the first hour of the tri, then sit down for 5-6 hours, then run for a few hours. The 50 is more grinding because you use the same muscles for ~10 hours. Recovery is also worse with backwards stairs for a few days.

I was in a running club in VA (Reston Runners rock!) who would provide a ton of support for the 50-100 RR runners each year, as well as a post-race pancake breakfast the next day. The carnage of limping, bloodied runners at that breakfast (many of them multi-time finishers) far exceeds what I see wandering around picking up T-shirts and Kona slots following an IM.

At the pointy end of the field, I think the competition is tougher at an IM, because the talent pool is larger and more intensely competitive, plus an 8 hour max effort is by definition harder than a 5-6 hour max effort.
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" I take my gear out of my car and put my bike together. Tourists and locals are watching from sidewalk cafes. Non-racers. The emptiness of of their lives shocks me. "
(opening lines from Tim Krabbe's The Rider , 1978

IMHO, 50k/50milers have better on-course catering. Oatmeal creme pies, Oreos, m&ms, donuts... Really just a fat kid's dream.

Not to derail the thread (I have yet to do either but have a 50 scheduled in the fall) but you just can't beat a trail run aid station... "do you want some pb&j to go with the m&m's and chips? Keep going! We got quesadillas and beer waiting at the finish!"

It's kinda fun how trail races still have a low key "the real goal is to have a good time" vibe; at least the ones I've been to.

Back on topic: I'd agree that racing vs participating is a big differentiator. The worst I've trashed myself was racing a marathon but on a comparable course running 45 sec/mile slower was fine the next day. I'd say it all depends how close you come to your limits--either intensity or duration--during the event...

Personal opinion: It depends on the course. A flat 50 miler is easier than a flat IM distance race. Elevation gain/loss, terrain, cutoff times and weather alter things. Half of UTMB vs Norseman?
If it's just to finish within cutoff,I think an average 100 km race with an 18 hr cutoff time is closer to an average IM distace race. Likewise, a 100 miler could be close to a double IM.

Having done both a few times, I personally think that a 50 mile run is harder than an Ironman when both are done on courses of similar profiles and taken at similar intensities.
In terms of wear and tear on your body, the 50 miler takes a bigger toll.

In my eyes, the primary point in favour of the Ironman being harder is that you have to reach a certain standard in all three disciplines to be able to finish.
Although with this in mind, I would argue reaching the relatively lower level in each of the three is easier than reaching the higher level of running ability required for a 50 mile run.

I just ran rim2rim2rim on Monday, we did it as a bucket list, enjoy the day thing. This was much harder than an IM for sure , I think the single biggest point of this run was you HAVE to finish, no drop out point, shuttle, mule, chopper to take you the final 6 miles out of the canyon, so this 47 miler was harder than an IM for sure. I doubt a road or less hilly route would feel the same. Try it, than tell me. Worth a every pain I feel right now!

I've completed 4 IMs(7 year timespan) and 5 50s(2.5 year timespan) and my last two 50s were at "easy" pace. I'm a runner by nature. For me, I take a massive beating during the 50 while the IM is easier on my body. I think training for an IM is WAY harder than training for a 50.

Hilly 50 PR (Mt. Hood 9 flat), Hilly IM PR (IMMT 10:07 w/ 3:17 run)
Flat 50 PR (Prairie Spirit 8:33, training/easy effort), Flat IM PR(IMMD 9:56 w/ fast first 10 miles, side ache, easy last 13 miles marathon)

I also say running at your limits for a standalone marathon is HARDER than an IM.

This. I've done 4 IMs (Finished 3), best one just sub-10. Absolutely smashed after all, incl. the DNF. Took several days to a week to feel normal again. I just did a 50 miler (in 11:45), and even though my legs felt more trashed right after the race, I bounced back within a few hours. Using only one mode of transportation requires a much more conservative starting pace if one hopes to finish at anything but a crawl, as you're finishing with the same muscle groups you're starting with. Knowing I'll not use my arms again allows me to swim at a less conservative pace. This is less so with the bike, but still somewhat true. But there's still the apples/oranges thing: I've raced all my IMs, and was just trying to finish the 50 miler.

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Hard work beats talent when talent doesn't work hard.

I think using work done is the best way of getting around the "apples/oranges thing". A person can be totally trashed after any big effort, or series of efforts. I've done one IM and one 50-miler but TBH, I felt most trashed on the day after my hardest training week pre-IM where I went 40,000 yd sw/300 mi bk/60 run. I did not feel nearly as bad the day after the IM or the day after the 50-miler.

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."