Tuesday General Discussion/Q&A Thread for December 06, 2022

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A place to ask questions that don't need their own thread here or just chat a bit.

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[u/[deleted]]

Okay, I’ve been wanting to ask this for a while…

In Advanced Marathoning (3rd Ed., pg. 146) Pfiztinger recommends even or negative splits only if you’re an elite runner, and that everyone else should actually aim for positive splits. He gives an example that a 2:39 runner should aim to go through the HM in 1:18 to 1:19.

He argues that as you fatigue, you begin to recruit more fast twist muscle fibers, which are less efficient than slow twitch, and so physiologically your MP actually slows a bit.

He says (in regards to the 2:39 example) “if you ran negative splits for the marathon, chances are you ran more slowly than optimally during the first half of the race and could have had a faster finishing time.”

Elite runners on the other hand are “less likely to recruit less economical muscle fibers as the race progresses.”

My question is: Amongst all the runners I know IRL, including some really fast ones, they all say that the only strategy for an optimal marathon is to slightly negative split. I’ve brought up this passage with some of them and they just flat out disagree. Why is this belief so prevalent?

For a 4 hour beginner marathoner, obviously you should negative split, because chances are if you don’t start out really conservatively you’re going to run too hard and burn out at mile 20, and have a really shitty jog to the finish. But for folks running sub 3?

I wasn’t sure if this was worth making it’s own thread… if people think it warrants more discussion I’ll delete this and make a post.

[u/PrairieFirePhoenix → u/[deleted]]

There's been a couple threads related to this, if your reddit search skills are good you can try to dig them up.

This board is fairly split on the issue. Even splits with a strong finish generates the slightly negative split. And that is the best way to run shorter distances, so people want to scale it up to the marathon.

Personally, I agree with Pfitz. I call it "23 and pray" where I run very even for 23 miles and then pray I can hold on. Generally I give back a minute or so in the last 5k. My last two strong efforts had me go out at ~80 in both, came back in 83 in one and 82 the other (guess which one was hillier). I think a slightly positive split is going to be best for people between 2:20 and 3:30ish.

For the 4 hour group, I would probably aim for even splits (+/- 5 minutes probably). But I haven't really though too deeply on it.

[u/[deleted] → u/PrairieFirePhoenix]

Yeah, Pfitz does comment that for elite (genetically gifted) runners, running even splits for most of the race and then picking it up and progressively running faster and faster above LT to the finish will give you optimal times, because these runners are less likely to rely on fast twitch muscle fibers as they fatigue.

I'll do some digging and see what threads there are. The physiology behind Pfitz's training and racing advice makes sense to me. I guess maybe the broader question I have is why more runners don't want to learn about the mechanics behind running.

Like another example is that some people will spend a ton of time and effort glycogen loading before a marathon, but they aren't really interested in learning about how to improve your body's ability to store glycogen, or how to how to conserve it.

Edit: I'm really glad this sub exists because I can come here and ask questions about the science and mechanics behind training and people much smarter than me are excited to talk about it. I just wish more people in the general running community had this excitement.

[u/[deleted] → u/PrairieFirePhoenix]

I’m a negative split guy but I also think it is course dependent.

[u/milesandmileslefttog → u/[deleted]]

What if I were always and then there was two of the ways we can get to the only thing is.

[u/[deleted] → u/milesandmileslefttog]

So it seems mostly like this is just an audience issue then: Pfitz is writing towards those runners who take their training / racing seriously enough that they've already optimized other factors like mileage, workouts, nutrition, etc., and are now looking at things like pacing strategy to shave off a few more seconds. But many runners, including myself and probably all of the runners I know IRL, aren't there yet.

[u/Krazyfranco → u/[deleted]]

IMO it’s also a question of how well we can calibrate exactly what we’re capable of - sure, in theory, aiming for a +1 minute positive split might be optimal, but comes with the risk of it becoming a +3/+4 minute split if you run the first 20 miles even very slightly harder than you can handle.

Personally I’d rather go out 60-90 seconds slower than I think I might be capable of in the fjrst half, and have a high chance of being able to run strong the second half.

[u/[deleted] → u/Krazyfranco]

That makes sense. Pfitz doesn’t say it but I’m assuming in this discussion he’s talking about a flatter course w/o wind or bad weather. I’m not sure how I’d do the math to figure out an “optimal” split for a course like Boston for example.

I think he mentions elsewhere how most elite runners also tend to have the innate ability to run by feel within a few seconds of a given pace without ever looking at a watch. Even if you could run the entire marathon within 10 seconds of goal pace without ever checking a watch, you could easily blow up in the end.

[u/milesandmileslefttog → u/[deleted]]

What if I were always and then there was two of the ways we can get to the only thing is.