This question needs to be answered as well.
Coming at this from a math background, I look at this as a two-variable optimisation problem. For a fast marathon you need both high aerobic capacity and sufficient strength/endurance to use that aerobic capacity for the whole marathon. Sketching out the argument (without deriving the physics by formula):
Aerobic capacity: I assume the fastest possible time you need to run at your aerobic capacity the whole way as running at anaerobic levels for substantial length of time would lead to cramp/breakdown/not finishing. That is your aerobic capacity is a limit to your power production, and to get the maximum speed from fixed power would lead to wanting to minimise your weight.
Strength: The runner would need to have sufficient strength to be able to sustain their maximum aerobic speed over the whole of the race. They may also need a little more in case of wanting to be able to run faster patches for tactical reasons, managing their speed downhill, for injury prevention (especially through training) etc. There be effects of a larger muscle being able to store more glycogen which would improve endurance.
Proposed solution: The runner needs to be as light as possible subject to having sufficient strength to maintain maximum aerobic speed and carry enough glycogen. While that doesn't lead to an exact answer (and never will) the line of reasoning could be used to determine what is limiting a particular runner.
Intuitively this make sense to me as the shorter the race the more anaerobic/strength based and therefore the larger the athlete, which would appear to be the general trend.
The bell shaped curve was quite helpful in explaining the video. Thanks for the explanation I always find your post and explanations insightful and courteous. That is why I did not post my numbers because clearly I was on the other side of the bell curve.
I would still argue using visual evidence (Googling top marathon runners) would produce evidence having access muscle or fat is not desirable.
I get the point again with the bell curve in mind that a scrawny AF normal dude that wants to run a marathon might benefit from some weight training. But this same bell curve idea would then mean that as you get to the other side of the curve (or around half the people) would benefit very little from strength training.
Well, okay.
I think the bell shaped curve idea is where I was confused. Because almost every other sport or activity strength and performance is going to be a linear relationship. The stronger you are the better you are going to be at it. Only in distance running or some other super endurance type event is there a point when getting stronger becomes detrimental to your performance. I guess I did not understand what you were saying in the video. Maybe next time hold up a picture of a bell distribution graph for me LOL.
I'm a visual guy that is why I love books charts and data!
I prefer to think in terms of diminishing returns.
Ceteris parabus, stronger is always better, but more strength comes with more weight. There is a sweet spot for all sports, but some sports that trade-off point is reached very early e.g. long distance or climbing/high jump etc. So a marathon runner would benefit from doing some squats as they could get quite a bit stronger with negligible weight gain - even if just improved neuromuscular efficiency.
Lightweight rowers in NZ (at least when I was still competitive) were encouraged to lift heavy - training around 3 reps and low volume to stay strong and not gain weight. The heavyweight rowers lifted with a bit more volume.
The amount of unofficial data that go through this forum is astounding. I asked your numbers mainly because I was curious about what your experience was specifically.
I wanted the information to be available should anyone ever find it useful or come across the thread in the future.
At this point, Zap knows he fucked up. I accept his apology.