Low 3 to 3 hour IM Run Split

Maybe this belongs in the Ironman thread…

For those that have got or targeted a 3 hour marathon whilst using the TR IM plan. How many more runs did you add to bring weekly mileage up and how did you structure this?

I know the bike and nutrition plays a large part in the equation but wondered if you guys got up past 45 miles a week?

I have around 3:30 IM run split and wondered if putting in easier runs to bring mileage up within the plan would help?

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Following with interest.

Did 3.09 at my first/only iron distance last year off 50-70k per week of running, with long runs ranging from 1h30m to 2h30m.

For reference, stand alone mara is 2.49 but if I raced one now I’d be going for sub 2.40.


I think you would be a good contributor to this subject tbh

My half time is around 1:19 so perhaps a 2:50 Mara open is there. How did you get down to 2:40 sub shape? I realise the plans have a run on the weds, thurs and weekend as well with a brick included but wondered really should be running 5 days a week or more?

I feel it’s not running too hard on the easy days, I’ve recently started restricting easy runs to 10 beats or more below Maff. Is this something you do?

The IM run seems more strength than aerobic based so I realise a lot of conditioning is needed perhaps more so than a normal marathon

I also did last year my first and only IM. I followed the full distance triathlon MV plan.

Got a 3u04 marathon. I believe with this same plan I would be able to go around 3u.
MV got 3u runs which is already long.

Now I plan on working on my speed this fall/winter starting with 5k and 10k. By building my speed I suppose I will be able to run faster in longer distance as well.

Open marathon I have a 3:00:30 :laughing:
But I believe I will be able to run 2:50.

If you followed for instance LV plan you could do MV or HV. Or just integrate those runs in your plan.

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First thing to say is that I use bike-only TR plans and then build in my own swim/run/S&C sessions.

I did London Mara 2018 in 2.49 but my running has stepped up in the last 2 years - 73:47 HM, 33:38 10k, 15:56 5k.

The key for this has been consistent 4-5 runs per week, with one of those being intervals at threshold or above. The remaining running has been entirely easy at 4:30-4:50/k, but guided by RPE on the day. As you suggest, this tends to be at a low heart rate of around 70-75% HRmax.


Impressive, can I ask what distance your long run is per week?

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That’s very impressive. I compete in Duathlons and have been wondering how to incorporate runs into the TR cycling plans. I’m about to start a new TR plan but i’m torn between the Tri specific plans or cycling only - any advice?

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In the build for Roth I took my long run up to 2h30m. I did 6 runs between 24 and 32k.

I’ve stuck to LV cycling plans - SSB and sus power build. That allows me to add a long aerobic ride along with my swim/run sessions whilst also complying with the TR plan.

By doing the cycling plans I get more high intensity bike sessions (than in the tri plan) and I find that the fitness translates well to running to allow me to get away with just one hard run a week.

If I did the TR tri plan I would also have low compliance as I need to retain a degree of flexibility for work/family/etc.


Thanks, really great advice.

I’m in a similar position with my existing schedule of runs and S+C training - will look into the plans you suggested.

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This is optimistic but doable. My guess would be 2:55 with a 1:19. Too many variables. Sadly running fitness is not linear and not everyone run equivalents. My 5k PR is significantly faster than my marathon PR would suggest (17:42 vs 3:59:48)

This is Key. Not everyone can sustain this level of training (or have the time)

Like most things in life:
Tell me how much time you have to train, and ill tell you haw fast can you become.

If you are a good runner (a 1:19 half tells me you are) and are willing to do 20+ hours a week of training, then you just need volume and hope your legs can hold.

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Great to get that insight. I’ve been stuck at my current times of 79ish for a half for a few years. Perhaps trying to run twice per week hard along with hard biking has meant I can’t absorb the training. Not that I’d get as quick as you but I hoped to get slightly quicker on my times. Very interesting around SS training instead of the Tri as well. I’ll have a look at how how I could do the same for the next IM

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Yes, I think you are right. I’ve focussed on speed before and that’s why I severely bonked on the Ironman run halfway through. I’ll step the volume up and cap the pace at heart rate. I don’t have great recovery from hard running so can easily ruin a week of training with one run that’s too hard which was meant to be easy then the next day you wake up feeling like death