why i never see a PRO in an ironman marathon doing a negative split?
while elite marathon runners try always to achieve it, it seems that in the ironman is close to impossible or probably not the best strategy
what about you? did you ever manage to negative split your ironman marathon?
i wonder if I should abandon the strategy of starting super easy the first 10k of the ironman marathon and instead, go by “feeling” even if it seems too fast on the garmin…
No but there’s some of evidence that cooking the first few miles in the IM marathon is not very productive. Jim Vance used to take first mile splits in Kona for many years and the top guys almost always started at about the average pace.
https://coachvance.blogspot.com/2011/10/analyzing-ironman-run-for-kona-pro-men.html
https://coachvance.blogspot.com/2013/11/kona-2013-run-data-pro-women.html
why i never see a PRO in an ironman marathon doing a negative split?
while elite marathon runners try always to achieve it, it seems that in the ironman is close to impossible or probably not the best strategy
what about you? did you ever manage to negative split your ironman marathon?
i wonder if I should abandon the strategy of starting super easy the first 10k of the ironman marathon and instead, go by “feeling” even if it seems too fast on the garmin…
Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
I negative split my first IM marathon, but it was because I had taken a lot of sage advice to start slow and build.
Started about 20 seconds above goal pace, descended to goal pace by mile 10 and hit under goal pace on last 10.
I don’t see why it can’t be done more often, but it requires excellent bike fitness and near perfect fueling strategy.
I’ve thought about this too and come to the conclusion that a negative split marathon is not a good plan for Ironman. Seven to nine hours into a race isn’t the time where most of us can plan to kick it up a notch or two. In fact halfway through the marathon is when it hurts the most in a Ironman. I’ve finished 18 Ironmans and usually had good races but I have never once in the late stage of the marathon and thought to my self I feel great, I should run faster. The TV highlights are usually people cramping or crawling in the last few miles, not sprinting to the finish.
My plan is start the run at whatever speed feels good (which is usually a little too fast) and try to hang on for as long as I can. I always fade but can usually average a respectable run.
In an IM, I basically always have the same pace over the whole marathon. I pin my HF on 140 the first HM, and than I keep the pace on the second half.
My secret: a gel every 15 minutes.
I also condsidered the following replies:
it’s happened to me twice, both times because of coming off the bike under nutriented and then getting caught up in the first half of the marathon and then feeling cooler during the second half and the pace just magically came down. Not my doing either time.
Eric
This is the best one
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Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
You arent wrong. But also doesn’t seem relevant as to why people dont negative split the marathon leg. If you start the marathon with half a tank of gas then halfway in you have half of that left so theoretically the negative split should be possible
it’s happened to me twice, both times because of coming off the bike under nutriented and then getting caught up in the first half of the marathon and then feeling cooler during the second half and the pace just magically came down. Not my doing either time.
Eric
This ^^. Happened to me in my first IM marathon by pure luck and like EricM said I wasn’t really driving the pace, my body just responded to the nutrition and sped up. If I were more aware of what was happening then I might have tried to push the pace more, but after tanking in miles 4-8 my mentality was just to get through it without walking.
Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
You arent wrong. But also doesn’t seem relevant as to why people dont negative split the marathon leg. If you start the marathon with half a tank of gas then halfway in you have half of that left so theoretically the negative split should be possible
The question was “why don’t pros negative split” not theoretically the fuel required comes from places other than the gas tank.
The reason why is simple and has been stated already, people go out way too fast the first few miles.
The better question is why do they go out too fast?
I think it’s because no one wants to give up on the perfect race and be over conservative those first few miles. Ironman is such a long day, and everyday is different. Never sure what you’re going to have that day. So why start out exactly at the pace you think you could sustain for the IM marathon (or even faster!)?
To have the confidence to start out super conservative, a little math will help. Let’s say through your training you think you could run 7:30 pace all day. That’s a 3:16:30 marathon. Let’s say you decide to run 8 minute miles for the first 10k. You’re only adding 3 minutes (max) onto the marathon. And that’s assuming you could have actually run 7:30s for the whole thing. And if you could run 7:30s for the whole thing but ran 8s for the first 10k, you’ll most likely be set up very well for the back half and will make some of that time up. (you’ll have been able to better digest fuel & absorb hydration) But if you weren’t actually able to hold 7:30s, then running 8s the first 10k will possibly result in a 3:30 marathon rather than a 3:45 walk/jog.
Now pros, that’s a little different. They’re racing and are kinda forced to go for it. The ones going for the win anyway. The rest of them should be conservative as well and will find themselves flying up the leaderboard in the last 10k.
Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
You arent wrong. But also doesn’t seem relevant as to why people dont negative split the marathon leg. If you start the marathon with half a tank of gas then halfway in you have half of that left so theoretically the negative split should be possible
The question was “why don’t pros negative split” not theoretically the fuel required comes from places other than the gas tank.
Maybe the lack of punctuation made your point here unclear but it seems like you arent actually answering the original question
I personally don’t know the answer but would imagine it is just because it is easier to run fast off the bike or that the pro’s are racing for place rather than time so they will start the run hot to try and catch the pros ahead of them. Id be interested to see what the pros who come off the bike in the front run in terms of splits. Id imagine they are more conservative and are less likely to positive split
I had a negative split for Ironman Canada last weekend although not a pro. This was largely because I went out nice and easy and then I had a porto stop at 19km so I was lighter for the second half haha
I think a reason a lot of Pros don’t negative split is because often your best time would be you going a touch faster than you should and then digging deep AF the last few KMs to hold on. If they know they can run a 3hr marathon on a good day, why would they run at 3:10 pace and then speed up and finish at 3:00-3:05. Instead if you start at a 2:55 pace and then you just hope that today is your day and you can hold on and if not you fade a bit and hope you still finish around 3.
Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
You arent wrong. But also doesn’t seem relevant as to why people dont negative split the marathon leg. If you start the marathon with half a tank of gas then halfway in you have half of that left so theoretically the negative split should be possible
The question was “why don’t pros negative split” not theoretically the fuel required comes from places other than the gas tank.
Maybe the lack of punctuation made your point here unclear but it seems like you arent actually answering the original question
I personally don’t know the answer but would imagine it is just because it is easier to run fast off the bike or that the pro’s are racing for place rather than time so they will start the run hot to try and catch the pros ahead of them. Id be interested to see what the pros who come off the bike in the front run in terms of splits. Id imagine they are more conservative and are less likely to positive split
Yes, my point was unclear. Do an ironman and educate yourself.
Stand alone marathoners are starting the race with a full tank of gas. (half way thru, they still have half a tank)
You arent wrong. But also doesn’t seem relevant as to why people dont negative split the marathon leg. If you start the marathon with half a tank of gas then halfway in you have half of that left so theoretically the negative split should be possible
The question was “why don’t pros negative split” not theoretically the fuel required comes from places other than the gas tank.
Maybe the lack of punctuation made your point here unclear but it seems like you arent actually answering the original question
I personally don’t know the answer but would imagine it is just because it is easier to run fast off the bike or that the pro’s are racing for place rather than time so they will start the run hot to try and catch the pros ahead of them. Id be interested to see what the pros who come off the bike in the front run in terms of splits. Id imagine they are more conservative and are less likely to positive split
Yes, my point was unclear. Do an ironman and educate yourself.
Yes because myself, not a pro, doing an IM will shed light on why pros dont negative split the IM…
Now pros, that’s a little different. They’re racing and are kinda forced to go for it. The ones going for the win anyway. The rest of them should be conservative as well and will find themselves flying up the leaderboard in the last 10k.
wait a sec
many here writing “ironman pros are racing and they are forcedâ€
isnt the same for pure marathon elite runners? they all compete each other for a win but instead they pace themself nicely and if they see the other running an impossible pace, they simply ignore it
isnt it?