About This Tool
Training Load analysis helps you understand whether you're building fitness, accumulating too much fatigue, or are ready to race. The three key metrics — CTL, ATL, and TSB — are adapted from Dr. Eric Banister's TRIMP (Training Impulse) model, widely used by endurance coaches.
What is TSS?
Training Stress Score (TSS) quantifies the training load of a single session. It accounts for both intensity and duration. A 1-hour easy run might score 40–60 TSS, while a hard interval session could score 80–120 TSS.
CTL, ATL, TSB explained
Chronic Training Load (CTL) is a 42-day exponential moving average of TSS — your "fitness". Acute Training Load (ATL) is a 7-day moving average — your "fatigue". Training Stress Balance (TSB) is CTL minus ATL — your "form". Positive TSB means you're fresh. Negative means you're carrying fatigue. Racing well usually happens at TSB around 0 to +15.