How the race split table works
Even pace is the theoretical optimum — and a trap on race day
Physiology favors even effort, which on flat terrain is even pace. But two realities bend the optimum: glycogen fades in the final third (making late miles costlier), and banking time early spends fuel at exactly the moment fatigue compounds. The negative split — first half ~1% slower — trades a few seconds early for a finishing kick that passes hundreds of runners. It is the strategy of nearly every recreational PR.
The cost of going out too fast, quantified
The "positive split" option shows the classic failure: first half 2% fast feels easy for 40–70 minutes, then the last third pays it back at a 5–10% pace penalty as glycogen bottoms and form collapses. A marathoner who runs 3:00 pace for the first half on 3:10 fitness typically finishes closer to 3:20 than 3:10. The wall is not mystical — it is arithmetic plus empty glycogen.
How to use the table
- Memorize three checkpoints, not forty numbers: 25%, halfway, and 20-to-go. Autopilot between them.
- Expect GPS error: city courses and tall buildings make watch pace lie by ±10–20 seconds. Trust the split table and course markers, not live GPS.
- Hills rebalance splits: push the uphills by effort (they cost less per second than they feel) and let the downhills pay you back — the table assumes flat.