Distance-specific training
Evidence: moderate
The energy-system demands of each event are well measured, and elite training broadly tracks them: more speed and anaerobic work at 1500 m, more threshold and volume toward the marathon. The principle is sound and descriptively supported, but the precise event-by-event prescription rests more on coaching practice than on head-to-head trials.
Events from 1500 m to the marathon sit on one continuum, but the balance of qualities they demand changes sharply along it. The starting point is the energy-system mix. Treadmill simulations of track events found the aerobic share of total energy was 66% for the 800 m and 84% for the 1500 m (Spencer & Gastin 2001). By 5 km and beyond the aerobic share is higher still and keeps climbing toward the marathon, which is almost entirely aerobic. That gradient is why training emphasis shifts. The shorter the event, the more anaerobic capacity and top-end speed matter; the longer it is, the more the result is decided by lactate threshold, fractional VO₂max utilisation, running economy and fuelling. See energy systems for the underlying physiology.
One feature is shared across the range. Elite runners from 1500 m to the marathon all build on a large base of easy aerobic volume, then layer event-specific work on top (Haugen et al. 2022). The volume base is common; the sharp end is what differs.
The continuum
Where the emphasis sits by event
- 1500 m. Still substantially anaerobic, around 16% of energy (Spencer & Gastin 2001). Needs real speed and anaerobic capacity and speed reserve, VO₂max work, and the ability to handle high lactate. Volume is moderate; the closing kick is decisive.
- 5 km. The classic VO₂max event. Heavy on intervals at and around VO₂max pace, threshold work to lift the sustainable ceiling, and enough speed to finish. Specific endurance means holding close to VO₂max for the full distance.
- 10 km. Shifts toward lactate threshold. Threshold volume rises, VO₂max work stays, speed work narrows to sharpening. Specific endurance is the ability to sit just below threshold for half an hour.
- Half marathon. A threshold event. The goal pace sits near lactate threshold, so threshold and tempo volume dominate, with longer specific runs at goal pace.
- Marathon. Decided by threshold, economy, durability and fuel. Very high easy volume, large threshold blocks, long runs and marathon-pace work, plus a fuelling and glycogen plan. Holding pace late when tired is the event-specific quality.
- Ultra. Volume, fat oxidation, durability and gut tolerance dominate. Top-end speed is almost irrelevant; time on feet and fuelling tolerance are everything.
Specificity narrows toward the race
The practical principle that ties the continuum together is funnelling. Training starts general, with broad aerobic and speed development at both ends of the spectrum, then converges on the goal race pace as the event approaches. This is the logic of the Canova method, where the specific period before a marathon is built around getting comfortable at race effort, raising power-endurance and aerobic endurance while holding aerobic power (Davis 2011). The same funnelling applies at every distance. A 5 km runner narrows toward 5 km pace, a marathoner toward marathon pace, each from their own mix of faster and slower work. See periodisation for how this sequences across a season.
Training intensity distribution also shifts along the continuum. A descriptive review found marathoners leaned more pyramidal, with a large base and a tapering amount of harder work, while 1500 m runners trained more polarised, pairing easy volume with a higher dose of very hard work (Casado et al. 2022). Both rest on high easy volume; they differ in how the hard portion is shaped.
Fuelling scales with duration
The longer the event, the more the result depends on fuel rather than pure fitness. Glycogen is rarely a limiter in a 5 km but is central to the marathon, where running out of carbohydrate is a common cause of the late-race collapse. From the half marathon up, in-race carbohydrate, carbohydrate loading and the durability to resist fatigue late all move into the foreground. For ultras, gut tolerance of high carbohydrate intake becomes a trainable performance factor in its own right; see gut training. A marathon training block that ignores fuelling rehearsal is incomplete in a way a 5 km block is not.