From 10K
to marathon.

01 / Two systems

Two systems, one runner

A 10K is decided mostly by VO2max and anaerobic power, the engine that lets you hold a hard effort for 30 to 60 minutes. A marathon is decided mostly by aerobic economy, the engine that has to keep running efficiently for two, three, sometimes four or more hours, long after the body has switched from burning mostly glycogen to leaning harder on fat.

Almgren's 10,000m speed proves he has one system built to an elite level. It says nothing yet about the other. That is true for him at the front of the field, and it is just as true for a recreational runner using a strong 10K to guess at a first marathon.

03 / Why

Why 10K speed does not transfer directly

VO2max, your aerobic ceiling, is trained with short, hard efforts and shows up fastest in the 10K, where a race lasts well under an hour. Marathon performance leans on a different quality: how efficiently your body uses oxygen and fuel at a controlled pace, held for hours, not minutes.

That efficiency, aerobic economy, comes almost entirely from volume. Specifically, from months of easy, conversational running that most 10K-focused training plans do not include in the quantity a marathon needs. A runner can have real VO2max and real 10K speed while still being underprepared for the specific demand of running efficiently for three, four, or five hours.

05 / Factors

What actually decides where you land

Two runners with an identical 10K time can land at opposite ends of the same predicted range. What separates them is not talent on race day. It is what they did in the months before it.

Weekly mileage

More consistent weekly volume builds a bigger aerobic engine, the same one that has to carry you through the marathon's final third. A runner averaging 25 kilometres a week and a runner averaging 60 can post the same 10K time off very different bases, and only one of them is ready for 42.2.

Long run consistency

The long run is the one session that rehearses the specific demand of the marathon: hours on your feet, fuelling under fatigue, running efficiently when glycogen is dropping. Skipping it, or keeping it short, leaves that demand completely untrained until race day itself.

Aerobic base depth

This is the sum of the two above, built over months, not weeks. It is what determines whether your marathon pace sits comfortably below your threshold, or right up against it for 42 kilometres straight. A deep base is what lets you hold the ceiling number. A shallow one is exactly why the realistic number exists.

The bridge: how Run Mastery builds it

Moving from a 10K focus to a real marathon-ready base follows the same five-step framework behind every distance at Run Mastery, applied with marathon-specific weighting.

• Understand zones: know exactly what easy, threshold, and hard actually mean for your own heart rate, not a guess.
• Build base: the longest step for a marathon by far. Weekly volume grows steadily, and the long run extends further than it ever needed to for a 10K.
• Add threshold: raises the pace you can sustain for longer, which matters more here than in shorter races.
• Add VO2Max: maintained, not chased. Your 10K speed already proves this system works. Marathon blocks use just enough of it to keep economy sharp.
• Test and race: long runs at goal pace and a taper that respects how much the base, not the speed, decides the outcome.

Whether Almgren's 10,000m speed carries into a strong result in New York will come down to the same systems every runner has to build: the base, the long run, the aerobic economy underneath the speed. Speed is necessary. It has never been sufficient.