Wife asked an interesting question... (Page 3)

Nah, I think arguing with what's worked for others is a much more entertaining option.

PS - your workout is wrong.

I must concur! 

Nothing like doubling down on Dumb. lol

We are discussing race day nutrition not nutrition post or pre.  The problem with most IM athletes is that they have not practiced what they are actually going to do DURING the race and have their body adapt to it and find out problems with it.

Riding at IM effort will allow you to know what your body can handle at that effort on race day.  Just like the nutrition and hydration you take during the run at IM effort will also facilitate this.

Will there be some slight changes when you are actually out there on race day?  Perhaps, but only slightly.  The simulation you mention above if done at IM race effort (which is the only way to tell if you can process) would crush all but the most advanced long course athletes. 

Simulation is just that.  you are simulating what you will do that day and that includes everything from, sleep before, breakfast, nutrition, clothing, race wheels, helmet, etc.

I have no problem with the concept that there's more than "one way to skin a cat" but I also know it's not ideal to run for two hours after a six hour bike ride because the downstream recovery effect is going to compromise the next week's workouts.  Lots of plans call for race rehearsal days where you ride for 5-6 hours and then run for an hour.  This is mainly done to test race day nutrition and pacing and it's not done to get in an extra "run workout."  You don't need two hours of running after a six hour bike ride to figure out if you screwed up your nutrition and pacing.  Your body will probably let you know about 30-45 minutes into the run, if not sooner.  That extra hour you're adding to the run is not just doubling your run recovery time, it's probably exponentially increasing it.  Running just punishes the body.

As the old saying goes, I'd rather be 10% undertrained than 1% overtrained.

Because for me, an IM bike is going to be a 6 hour or so effort.  With a little more than hour swim, plus that hour after the bike that you later say is when nutrition issues show up, that will help me dial in my nutrition.  From my n=1 IM experience, I felt I needed more bike fitness.  I think that will help, plus help get ready for a long day.  I felt like the difference between a 5:45 to 6 hour day for a HIM was substantially different than my IM day, so not sure HIM is the only long day I want to do to prep.  Plus, I'm not really sure that I believe that nutrition issues show up within an hour or so (I know its not meant to be exact) of getting off the bike, so I think that longer days will help dial in what that feels like.

And, you assuming that is 8 hours slogging along in zone 1.  My 7 hour day was certainly not that, lots of climbing in there, which for me cannot be zone 1.

You're now kind of saying something different than what I responded to.  You stated you were going to ride for eight hours.  Now you're basically saying the eight hour bike ride will be used to somehow simulate a 1:00S/6:00B/1:00R.  An eight hour bike ride is in no way equivalent to a 1:00 swim, 6:00 bike and 1:00 run, especially if you're trying to simulate or replicate nutrition.  Why not just do a 1:00S/6:00B/1:00R as opposed to an 8:00 bike?  Nutritional screw-ups aren't going to manifest itself on a slow 8:00 bike ride like it would if you did a 6:00 bike and 1:00 run at IM pace.  I could take in 500 cal/hour just riding my bike and not have any ill effects.  I couldn't do that on the bike during a tri and expect to run after.  Trust me, I tried that once.  Would you like to see my hospital bills after that experiment went horribly wrong? 

You're right, there's no exact science as to when nutritional snafus are going to rear their ugly head on the run but I'm sure you've read some race reports in which people have had gut problems and the vast majority of those people knew they were in distress very early in the run.  Could it happen 2 hours into the run?  3 hours into the run?  4 hours into the run?  Sure.  Are you going to run for three hours after a training ride to see if that happens?  Nope, at least I hope not.  You can't simulate or replicate every race day scenario.  My point stands that super long days (especially those with runs) have a recovery hole that is often overlooked and not properly appreciated.

Yes, I'm assuming an 8:00 bike ride is slogging along in Z1.  It has to be.  You may have had moments in which you were riding out of Z1 (like on the climbs you mentioned) but the overall workout wasn't out of Z1.  I'd love to see a power file telling me otherwise because it's highly improbable that a MOP AG'er can ride out of Z1 for eight hours.  I'm FOP on the bike and I know I couldn't do it.

You mention you need more bike fitness.  There's other ways to accomplish that which don't involve spending eight hours in the saddle.  I'm just thinking of your comfort, bro. 

I gave me reasons why in a follow-up post.

When did I mention anything about a HIM?

To GMAN's point.  What is the extra hour of running getting you or your athletes following a 5-6 hour ride?  Is it a case of 5 hr ride = 2 hr run, or 6 hr ride = 1 hr run?

He brings up (in my mind) a really valid point about training stress.  If you can simulate the stress of doing a 6 hr ride, but do it in 5 hrs, why not take that approach - why endure a longer training session that needed?  (this question is aimed at everyone)  And again, can someone tell me what training adaptations are taking place by running for 2 hours off the bike?

My longest days during IM training were a stand alone 7hr (200km) ride at moderate intensity. The next weekend I did a 5hr ride at mid-to-race intensity followed by a 1hr 'easy' run. I felt much more tired at the end of this.

I don't doubt for one moment that it's a great confidence booster.  But you will have to properly recovery for at least a week.  As long as you're doing that, it's all good.

But I have found that most do not recovery from a workout like this.

I always appreciate someone looking out for my comfort!  I'm not saying that I'm right about long bike days, I think I'm always in a learning mode about how to approach the training.  And yes, for sure, a long day like that is going to be at a lower intensity.  I'd love to give you a power file too about what that day entails, since that would mean that I could afford a power meter!  Really, the thought about those long days was to address a couple of different goals.  I know I'm repeating myself, but just trying to sum up.  Not trying to emphasize my rightness.  One, continue to dial in nutrition.  Two, increase bike fitness with a goal of coming off the bike in an IM feeling like that was not a big deal.  So, that is what I'm was trying to address.

Now, bringing this back to the OPs original question, which was what will the longest training day be (at least I think that is where we started).  I think your point GMAN is that one doesn't have to do extremely long hours to get ready for that.  Which I think does raise a good point, that the question truly needs to take into account both duration and intensity.   If you can generate sufficient training stress in 4.5 hours, why not do that and take less time with less negative impact on the body, correct?  And I mean this as an honest question, how would you recommend getting ready to do 4.5 hours at a stress sufficient to generate that kind of training stress?

Regarding the two hour run after a long bike for training, my thoughts and keep in mind I've never done this or an IM but I would think if you are doing the bike and run at or near race pace then yes the recovery could impair future training, if it is done at a z1/2 pace recovery would be significantly less with the benefit of being active for 8 hrs.

I would imagine that this would vary greatly from person to person.

I do agree with the old saying though.

I've never done an IM either - hence I like reading the responses in this thread.  But IMO, a Z1/2 pace IS your IM run pace, and recovery after running 2 hours at that pace following a long ride is going to take a while (days).

We have a winner folks!

Yep x2.  *Ding-ding-ding*

To be honest... accomplishing that is far more difficult without a power meter and so much so that I don't even know how to answer that question or quantify it in HR or RPE terms.  I can talk power centric stuff all day long but I know my limitations with dispensing HR or RPE advice so I'll let someone more knowledgeable than me in those areas address that issue.

For the sake of reference related to power...

TSS (Training Stress Score) is a quantifiable measure of intensity and duration.  So you can plug in some variables within the TSS equation to get the math to work for a given parameter.

TSS equation = (seconds x NP x IF)/(FTP x 3600) x 100

For arguments sake, let's say that my TSS for my last IM was 250 and my FTP was 300 and my bike ride was 5:15 and my IF was .69 (69% FTP) which made my NP 207.

I can drop the time from 18900 seconds (5:15 in seconds) to 4:15 and figure out what NP and IF numbers I need to get to a TSS of 250.  Basically, I would have to ride at about 230 watts (almost 77% FTP) for 4:15 to achieve the "same workout" as riding 207 watts for 5:15.

Make sense?

Wish I could ride a 5:15 on that IF...

Serious question.  How did you determine the TSS score to hit for the IM?  Was this based on past races and your ability to run, or something else.  Also curious what % you would aim for in an HIM and what TSS that factors out to.

That does make sense.   Now, I know that this next question is going to get dangerously close to another topic that has been beaten to death in other treads, but if your goal for the workout is to get to a TSS of 250 (or x for any particular rider), where would you think that the increase in intensity and shortening the duration starts to not paying sufficient return?  While riding for a certain duration at 100% FTP/IF of 1.0 would give the same TSS, at some point I think you need a certain time in the saddle.  So, to try and give some guidance to the OP and for my increased knowledge, why is 4:15 the long ride that you have chosen in this example?  Why not 4:00 or 3:45 at a higher intensity?

I guess the way I was looking at it (without perhaps knowing it, or being right) was getting to a higher TSS through increasing the duration.

Transitions.