Cycling training terms,
explained plainly.
Every term here is something you’ll meet inside AdaptCycling — or anywhere power-based training gets discussed. Short definitions, the math where it matters, and how we use each term in the product.
FTP (Functional Threshold Power)
The highest average power you can sustain for approximately one hour. Used to anchor every training zone and workout prescription.
TSS (Training Stress Score)
A single-ride fatigue score that combines duration and intensity. One hour at FTP equals 100 TSS. Used to sum daily and weekly training load.
CTL (Chronic Training Load)
A 42-day exponentially-weighted average of daily TSS — the fitness side of the fitness/fatigue model. Rising CTL means you're accumulating fitness.
ATL (Acute Training Load)
A 7-day exponentially-weighted average of daily TSS — the fatigue side. ATL responds fast; it's why you feel flat after a hard block.
TSB (Training Stress Balance)
CTL minus ATL — your 'form.' Negative TSB means freshness-in-debt (high fatigue); positive TSB means you're rested and primed for a race.
Intensity Factor (IF)
A ride's normalized power divided by your FTP. IF 0.80 is a typical sweet-spot ride; IF 1.00 is an hour at FTP.
Normalized Power (NP)
A power metric weighted to reflect the physiological cost of variable efforts. A surgy crit can have NP well above average power.
Sweet Spot training
Sustained efforts at roughly 88–94% of FTP. Produces most of the aerobic adaptations of threshold work with less fatigue — hence 'sweet spot.'
Polarized training
Distribution where ~80% of time is zone 1–2 and ~20% is very hard (VO2max+), with little in the middle. Popularized by Seiler.
VO2max
Maximum rate your body uses oxygen during exercise. Trainable via short intervals (3–8 min) near maximum sustainable aerobic output.