Advanced Class: Pacing The Ironman Run
This morning, I read Tim Cronk's comments on Dawn Cass' IM MT race report, regarding the relative value of pace, HR, and RPE during the IM run. I want to respond, but don;t want to hijack Dawn's compelling report of her marvelous race - which if you haven't read, you really should: http://members.endurancenation.us/Forums/tabid/57/aft/21664/Default.aspx#233316
So I'm starting a new thread on this venerable topic. It's often at the top of our minds as we get ready for the big day; you might even say we are obsessed with it here @ EN. First, a warning: if you are heading into your first or second Ironman, you probably should stop reading right now. Whether you are "racing" or "participating", executing an Ironman is a complicated proposition, with a myriad of opportunities to royally mess things up. The race execution guidance our coaches have developed over the years really works, and is a great place to start (or even stay) if your goal is to survive your first IM, or to see how fast you *might* be able to go.
But at some point, as Tim alludes, metrics become limiters (reins), not whips. I firmly believe that if you want to have the fastest possible overall IM time, you must learn how to read and respond to the subtle, subjective feedback your body is constantly giving you, and use that to achieve, in the case of the run, an overall even pace - the proverbial even split, 13.1/13.1 times about the same. What follows assumes that you have done everything right up to the start of the run: training, taper, nutrition, bike pacing, etc, and are ready to unleash the beast on the marathon.
There is evidence that the best strategy for pacing is an even split between the two halves of the marathon, In my absolute best IM races, I achieved this (I have the mile-by-mile splits in a number of races to document this.) But it's not just me; looking at the progression of the world record in the marathon distance, we see the same pattern. Each time the men’s World Record in the marathon has been broken in recent years (as well as a recent women’s record), the runner ran relatively even first and second half splits:
| Athlete | 1st Half | 2nd Half | + / – seconds |
| Dennis Kimetto (2014) | 1:01:45 | 1:01:12 | – 33 |
| Wilson Kipsang (2013) | 1:01:32 | 1:01:51 | +18 |
| Patrick Makau (2011) | 1:01:44 | 1:01:54 | +10 |
| Haile Gebrselassie (2008) | 1:02:05 | 1:01:54 | -11 |
| Haile Gebrselassie (2007) | 1:02:29 | 1:02:17 | -12 |
| Paula Radcliffe (2003) | 1:08:02 | 1:07:23 | -39 |
True, stand alone elite marathoning is not the same thing as age group amateur Ironman racing. But It does give us some food for thought.
So how to get there? As I said, I'm a firm believer in "listening to your body" to achieve to your potential. (For a quick read on this topic from Amby Burfoot, a guy I went to college with, who won Boston in '68 when he was a senior: http://www.runnersworld.com/peak-performance/how-to-run-your-best-marathon-pace-guaranteed). Learning that language is not easy, I suspect (I;ve been at for 68 years now), but it is possible. That;s where experience - simply racing a number of times - and following metrics - HR and pace, both during and after the fact - are important. But the end result is really quite simple, in my view. I've found my best results when I allow two things to guide me during a race:
- Constantly asking myself the question, "Can I hold this pace for the reminder of the distance?"
- Constantly being willing to slowly crank up the feeling of effort from beginning to end.
People who've heard me on this topic before will recognize the following, but I can;t repeat it often enough. An even pace will not feel the same from beginning to end. For the IM marathon, it will start out feeling stoopid slow, about like the warm-up/first mile of a recovery run. From there the feelings progress (miles 3-7)through my LRP during the first third of a long run, into (miles 8-12) my TRP during the middle third of a long run, into a true MP (miles 13-16/7), into feeling like I'm running a half marathon by mile 18, a 10k by mile 22, a 5K by mile 25/5, and like I'm ready to die by mile 26.
Comments
^^THIS^^
In the end, that's about all you need to know. If at any point of the IM marathon your effort is making it feel any harder than it should be (ie, at mile 8 you have the feeling of a Steady run, one that requires you to focus a bit to maintain the pace), you should really consider going easier. It's then about ratcheting up your effort as the run progresses but realizing that at best the result is a maintenance of rather than speeding up of pace.
And so success is largely about going easy when it's easy so you have the mental and physical resources to go much, much harder when the race gets exponentially harder, which it does in about 3 mile increments after about mile 14.
@Rich - I recall a comment from you years ago that really stuck.... Its not about negative splitting via time its about negative splitting via RPE.... Again that description says it all.....You also have a very good way of describing HR as a means of how the body is reacting to the work you are doing... Maybe throw that in this thread?
When I first came to EN it was all about Pace and Power , very little discussion about HR....
Glad this was posted. One recurring thing I read in race reports is "My HR was too high so I slowed down" (this one is good for those who don't wanna push or risk it, but the real question is how it relates to how you feel) or "I could not get my HR to go higher." (this one is simply you dont have it or that is the HR for the day). Jim Vance talks about training/tracking but NOT racing with HR in his book Triathlon 2.0: Data-Driven Performance Training... Using it to figure out efficiency , stuff like distance per heart beat, and also showing divergences of HR vs. Pace vs. Distance or Time to show your fitness levels at various distance/pace...
I think for those of us who are newer at the sport and/or have never learned to really listen to our bodies, HR can be a valuable metric at least in the early stages of the run leg of a HIM or IM. I can only speak from my limited personal experience, but tracking and paying attention to my HR has served me well in several HIM races , and my first IM. I'm pretty sure I have negative split my best two HIM runs and my latest IM run by tracking HR early in the run leg.
That being said, it is overly simplistic to view HR in a vacuum and of course, in my experience, RPE, pace, mood, overall feel etc etc and HR are all synthesized into an overall assessment of well being during a race- pace and HR being the more 'objective' of the measures. being off in any of these should trigger a search for a problem and solution. As I get more races in all conditions under my belt, I don't doubt I will be able to rely more on feel and subjective factors than HR, but I don't think I am there yet (maybe close in the HIM distance).
On the bike, I think HR is important to keep track of as a window to physiological stress your body is under as that may affect how well nutrition is being absorbed- that's all I think about HR on the bike.
For the run, I think that HR is invaluable as a limiter for the first stages in a long course race. Legs almost invariably feel good after that long bike and there is a risk of me running outside of my abilities early, when that time could be spent taking in hydration/nutrition or just conserving muscle glycogen for later. If trying not to slow down is the goal, then it makes sense to take it 'easy' early-and HR limits enforce that over and above pace limits. If you are very disciplined with pace and feel and have tons of experience, tracking HR is likely redundant. I don't have that discipline yet.
HR limits or targets for later in a race don't make much sense to me however. Personally, after 11-13k of a half marathon or probably after 30k of a marathon I am only going to be able to run as fast as I can run, and I don't really look at HR any more (or pace). Then its just a constant assessment of 'how long can I keep this up' as Al alluded to. That works for me.
I value what all the veterans have to say on this really interesting topic, I'm just putting in my two cents from a newbie who has a lot to learn.
I too value the incredible amount of wisdom shared within this group from those who have raced, failed, pushed the limits, tested those limits and podiumed many many times.
Some random thoughts:
I am focused on ramping the RPE over the course of the 26 miles as stated below. For me, that does correlate with a steady to increasing HR as the data showed at IMTX and IMAZ and my two best IM times to date as well.
Below, if we had the HR detail for the races times posted, I wonder if it would also show and increasing HR over the course of those marathons?
I also often wonder, Can one, who has a well above average VO2 for their AG, sustain a higher HR, intensity, RPE longer than one who has an average Vo2 capacity. I am average and, does this mean, relative to one who is above average, do I need to be more careful about how I ramp that RPE / HR?
I never see the data on KONA AG qualifier avg Vo2 levels ..........wish I had that and wish I could correlate the data we speak of with that variable as well because I think it is yet one more piece of the overall puzzle not talked about enough.....
SS
The coach's model of going out "easy" and increasing RPE over time, regardless of what happens with HR or pace has helped me to negative split a couple of IM marathons so I know that model works for me, but your mileage may vary.
Thanks for consistently enlightening us all. I personally have applied much of your guidance and insight to my racing with great success.
I followed Al's and Tim's advice at IM CDA and had a 4:00 marathon on a 90+ degree day. It was a 7 minute PR for an IM marathon. Last year I did a 4:07 at Penticton after a bike that was 45 minutes longer than CDA. The only problem I had at CDA was that I couldn't start as stoopid slow as I wanted to but in the end it worked out OK. My heart rate went up from the mid 120's to the mid to upper 130's by the end but the RPE was through the roof by the end. One difference between CDA and Penticton was the number of people on the run. At Penticton there were only about 500 people that did the full IM so it was really lonely on the back side of the run. In CDA with 3 loops there were always people up ahead to catch and pass. So looking ahead, finding a victim and slowly running them down helped keep my mind off of the pain and agony.
SS, I have no idea what my Vo2 is, except for the estimate that Garmin gives me, and how that stacks up to others in my AG is a greater mystery. As I stated above my HR went up some, but it really didn't go up a lot after the first 13 miles and my pace remained pretty consistent throughout. Contrast that to CDA 70.3 in June when my HR was in the 140's for most of the run and the pace was about the same. However, I went into the HIM with only 45 miles of running in my legs in the 30 days leading up to it. Between the HIM and the IM I did 187 miles of running in 2 months so I suspect that is the reason for the difference.
To be honest, I cannot get the next race booked into the calendar however I have to warn the group...I may be pulling on everyone a lot more as I prep for 2017 to ensure I am super-sharp. If in the process I can add some of my 2 cents on the topics to help others, I look forward to that as well!