Resilience is the fourth performance factor
Medium confidence
Two runners can start a marathon equally fit and finish minutes apart. The difference is resilience: who holds that fitness over 2 to 4 hours, and who fades. Researchers now count it as a fourth performance factor, though how to train it directly is still being worked out.
Why it works
You build resilience the slow way. Long aerobic runs at moderate effort, steady weekly mileage, and eating enough during those long runs all feed it. Deeper down, the muscles' energy factories (mitochondria) may grow, and the body may get better at choosing which fuel to burn.
What it means in practice
For a marathon, the long run carries weight that shorter, faster sessions cannot replace. A plan with no progressive long runs past 90 minutes leaves the resilience piece unbuilt. For the half marathon and below, it matters less.
The evidence
-
Resilience, the ability to preserve running economy and neuromuscular function late in prolonged exercise, is a trainable performance attribute distinct from VO2max, lactate threshold, or fresh-state economy. Runners matched on VO2max and 10K performance still differ in how well they hold economy deep into a run: those who regularly train long runs over 90 minutes show only a 3.1% rise in oxygen cost across a 90-minute effort at ~80% VO2max, versus 6.0% in less-accustomed runners. Higher training volume, regular long runs, and strength work all track with better durability. Specificity applies too, so building resilience at race pace likely requires training at race pace, including long aerobic intervals such as the 15 × 1000m sets elite marathoners run; as a narrative review of a recent concept, its specific prescriptions still run ahead of the RCT evidence.
Why we call confidence medium
Jones (2024-2025) put resilience forward as a recognized fourth factor, backed by strong theory and observation. The methods to train it directly are still being developed and tested.
Where it applies
Marathon and ultra-distance runners. It matters less for races under 60 to 90 minutes.
Does not apply to: short-duration events (5K and below) where pre-fatigue values dominate.
Last reviewed Apr 30, 2026. See how we score.