Failed sub3 Marathon: Bad day or Bad training?

I relate because I often feel uncomfortable spending "so much time" running in view of my not so sporty friends or colleagues. I may feel like if I reach arbitrary goals like 1:20hm or 3h marathon I will "justify" my practice. I know it’s stupid and that no one actually cares and I should focus on myself. I think I should just meet some other runners.

Sure, the goals are arbitrary, but they're not stupid. They matter to you and that's what's important. You're not running for anyone else but yourself.

As for achieving sub-3, I will echo what others have said here (increase the mileage, do more specific work at marathon pace) but add one more comment: slow down your easy runs. Increasing mileage from, say, 50/wk to 70/wk is far, far less daunting (and carries much lower injury risk) if you back off a bit on your easy days.

There are a lot worse things you could be spending 5-10 hours per week of your free time on: Gaming, drinking, social media, sh|tposting, eating, watching sports or bing-watching stupid shows could all be considered a waste of time. But participating in a sport like running is so bad?

I mean the dude is definitely bonking, but sure we can all vote. :)

Ever wonder why the pace for the 1/2 and the marathon world records is essentially the same?

Because outside of a little additional muscle fatigue if you have properly fueled and hydrated nothing has changed metabolically.

You are on the low end so it could be endurance. But you also don't mention any speed work. Your legs are never going to go fast if you don't train them to go fast.

Your ½ times indicate you are underperforming for the marathon, likely as a result of lack of marathon-type runs whether long runs, tempo or marathon pace. Super rough estimate for ½ to marathon result would be double your time and add 10-15 minutes. Your 3:40 off a 1:29 should have been closer to a 3:15-20 so you "underachieved" there as well. Your most recent result shows you have good enough ½ marathon time to run sub-3, but like your initial marathon, lack a combination of long run, tempo, marathon pace to hit your goal marathon time.

A ½ marathon is a good indicator of marathon potential, but obviously doesn't guarantee similar results as it's 13 miles longer. Comparisons really break down a bit more than say 800 to 1500 or 5K to 10K.

40 mpw is pretty low for sub-3 goal. If you are limited by time you really need to up the quality of those runs with tempo/marathon pace efforts and the occasional long run. You could get by on 40 if you trained say 4x a week with a long run of 15-20 and 3 other runs with 2 being tempo and one easy run. I'd drop a marathon pace run in place of the long run 1x a month and a tempo/long run 1x a month in place of long run too.

If you're looking to maximize your potential, and willing/able to put in more miles, then you should be able to do at least 2:4x.

I'm generally stronger at shorter distances (800 guy in college). So my performances tend to drop off slightly at longer distances. But my best marathon was 2:51 at age 46, a few weeks after a 1:20 HM and a 59:xx 10M, on mileage that peaked around 70 mpw.

You clearly don't need to worry much about building speed. So you should be able to just slow things down and add the miles. My single biggest revelation in marathon training was the benefit of 1-2 mid-week medium long runs (11-15 miles). Those made the weekend long run soooo much more doable.

No it isn't 'essentially' the same.

It hold the same proportion as for the 3 hr runner, and the approx the same for most double distances at a ratio of 2.1

HM 57.5. M 121.15 = 2.1

5km 12.6, 10km 26.2 = 2.08

Two things.

Your potential is much higher than just sub 3 if you can do sub 36off 35km/w

You have way more talent than most of the posters here.

Your sub 3 problem is not a mileage issue, it is not like you are going for 2:45 which should be your current benchmark. You are running so far within yourself for a sub 3 that the mileage is enough.

Like I said, essentially the same.

Now compare the marathon pace to the pace for the world record at 50 or 100 miles (or even Ironman marathon) where something HAS changed metabolically and you'll get my point (possibly).

Did you understand what IaS said?

I agree. More mileage may help but it was almost certainly that last few weeks that wrecked you