With how the sport has changed, it seems to me that doing 13-15 x Mile at MP with a short recovery is more specific training than sloggng about for 2+ hours.
Am I missing something? Is the long run just a tradition that people cannot break?
I mean OP is not wrong. Doing 20mi+ runs slow are a waste of an effort.
If you're doing a proper marathon cycle you should treat the long run as a workout day and therefore do part of the LR volume as reps or ideally MP (or 95%-98% of MP)
The only demographic that benefit doing an entire 20 mile run at a slow / totally easy pace are those just trying to run a marathon (with no time goals).
What is classed a a proper marathon cycle? What is the quickest you could run a marathon with just treating the long run as time on feet? Genuinely curious about this and getting some specifics?
Fat oxidation at MP for high level runners is very, very low. It has to be because they're already over 80% of VO2max, at fat metabolism requires more oxygen per ATP than carb metabolism. It doesn't matter, though, because it's very easy to fuel a marathon exclusively on carbs.
Improved fat oxidation at lower intensity levels is still a really a good thing because it's an indicator of aerobic fitness, but it's basically irrelevant as a fuel source in distances shorter than ultras.
But by improving fat oxidation, are you not improving your aerobic infrastructure so that when you do get into the higher intensities, where carbs become the main energy source you have a larger reserve and don’t overheat as quickly?
Assuming you mean "overheat" metaphorically and "larger reserve" to mean aerobic capacity rather than energy stores, then yes. If you have access to the right equipment, you can measure respiratory exchange ratios, and improved fat oxidation at the same pace is a pretty reliable indicator of improved aerobic fitness.
My point was just that fat oxidation itself doesn't matter much; it's only an indicator, and an indicator that 99.9% of athletes have no good way of checking. There is an inexpensive, consumer-grade RER sensor on the market, but it only works at rest. Otherwise you're looking at something like the VO2Master, which is $7500 (and that's cheap compared to other options).
But by improving fat oxidation, are you not improving your aerobic infrastructure so that when you do get into the higher intensities, where carbs become the main energy source you have a larger reserve and don’t overheat as quickly?
Assuming you mean "overheat" metaphorically and "larger reserve" to mean aerobic capacity rather than energy stores, then yes. If you have access to the right equipment, you can measure respiratory exchange ratios, and improved fat oxidation at the same pace is a pretty reliable indicator of improved aerobic fitness.
My point was just that fat oxidation itself doesn't matter much; it's only an indicator, and an indicator that 99.9% of athletes have no good way of checking. There is an inexpensive, consumer-grade RER sensor on the market, but it only works at rest. Otherwise you're looking at something like the VO2Master, which is $7500 (and that's cheap compared to other options).
Yes to both. I know fat oxidation falls off a cliff once you get to marathon pace so, I don’t disagree with anything.