METHOD · RUNNING

How we train for running.

At Splits we train running with three validated methods: 80/20 polarized, FIRST 3+2, and Norwegian threshold. The numeric anchor is VDOT (Daniels), an aerobic-capacity metric that translates your best time at a distance into target training paces for each pace zone we use across plans.

Context

At Splits we chose a polarized 80/20 approach: most of your weekly mileage stays easy and aerobic, with about 20 percent of well-directed quality work. We pair it with functional strength, and we never chase shortcuts.

What matters to us is consistency. Every training block should repeat week after week without piling up fatigue or injury. We've watched athletes who respect that logic make steadier progress than those who push hard intensities all the time. The calculator gives you a starting point for your level; the method tells you how to train toward it without breaking the body.

Methods

Three training families inform the plans we're publishing. We picked them for the evidence behind them and for how well they fit athletes with limited weekly time.

  • 80/20 polarized

    Seiler and Fitzgerald describe it as 80 percent of training time at easy intensity and 20 percent at hard. It anchors our beginner and entry-level plans.

  • FIRST · 3+2

    Three quality runs plus two cross-training sessions per week. We like it for athletes who already have a base but limited weekly hours.

  • Norwegian-inspired threshold

    We adapt the Norwegian double-threshold logic into a single weekly session. Steady work just below threshold, without driving athletes to exhaustion or the original two-a-days.

How we derive the numbers

For the calculator's baseline times we anchor on VDOT (Daniels) as our numeric reference. Each level — new, beginner, intermediate — maps to a plausible VDOT for that athlete. The table below shows the resulting times for standard distances. We chose conservative ranges on purpose: we'd rather underestimate than over-promise.

Baseline running times by level and distance
DistanceNewBeginnerIntermediate
5 km00:45:0000:35:0000:30:00
10 km01:35:0001:15:0001:00:00
Half marathon03:15:0002:35:0002:05:00
Full marathon06:30:0005:15:0004:30:00

Sources

We back every decision with accessible literature. The four sources below are our primary references for running; we revisit them whenever we need to sanity-check a pace, a progression, or a load week.

  • Jack Daniels — Daniels' Running FormulaHuman Kinetics, 4th ed. 2014
    link
  • Matt Fitzgerald — 80/20 RunningNAL Trade · 8020endurance.com
    link
  • Bill Pierce, Scott Murr, Ray Moss (Furman Institute) — Run Less, Run Faster (FIRST method)Runner's World
    link
  • Marius Bakken — Double Threshold Training (Norwegian Method)mariusbakken.com
    link

When it doesn't apply

These methods are a reasonable starting point, but they don't cover every case. Below we list the moments when it makes sense to look beyond Splits or consult someone who knows your specific context.

  • These general guidelines don't replace a coach who knows your history, prior injuries, and load peaks.
  • If you're starting from zero, do 4 to 6 weeks of walk-and-jog intervals before applying strict 80/20.
  • Beyond 50K the models need adjustments (more easy volume, less quality work). We don't cover ultra-distance yet.
  • Any persistent pain or fatigue that doesn't ease with rest needs medical attention before more training.
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