Fitness vs Fatigue — CTL / ATL
CTL = long-term fitness built over 42 days. ATL = short-term fatigue over 7 days. When CTL > ATL you are fresh; when ATL > CTL you are building load.
Form Score (CTL − ATL)
Positive = fresh, negative = fatigue. Thresholds: ≥+10 Peak (race-ready), 0–+10 Fresh (taper/recovery), −10–0 Building (normal training load), <−10 Fatigued (risk of overtraining). Post-ultramarathon dip (Nov 2024) is a useful reference point.