Coaching & planning · Coaching
Thresholds, zones, and calibration
How FTP, run threshold, and CSS resolve execution targets — and when to recalibrate.
Brick prescribes intensity as a fraction of threshold — bike FTP, run threshold pace, and swim CSS — so one model drives zones, compliance, graphs, and device export.
Why thresholds matter
Thresholds calibrate execution— they turn a prescribed fraction of threshold into watts, pace, or heart-rate bands on your device. They do not decide how hard the engine intends the session to be: that fraction comes from the workout type and training phase. If thresholds are wrong, "easy" is too hard and "threshold" is chaos. Calibration during onboarding and later recalibration keep targets honest as you get fitter (or return from a layoff).
Session duration is driven by weekly volume and your personal training history, not by FTP alone. See How training plans are built.
Zones
Zones are derived from your thresholds. Session steps show both the fraction and the zone so you can execute by power, pace, or heart rate depending on the workout type and device. Easy / Z2 and recovery sessions usually target heart-rate bands; quality bike work targets power; quality run and swim work target pace (CSS for swim). Sustained threshold efforts may also show an HR cap so cardiac drift does not quietly turn a power or pace session into a gray-zone grind. Profile → Zones shows your current maps.
Calibration and fitness tests
Use Plan → Recalibrate (or the calibration form in onboarding) to update thresholds, availability, and schedule prefs. Fitness-test weeks can be overlaid on the calendar when you need a formal check-in.
After a meaningful change in fitness, recalibrate sooner rather than forcing old numbers onto new physiology.
Compliance
After you sync, Brick compares execution to the prescription. That feedback feeds debriefs and, over time, readiness and limiter context — closing the loop described in How Brick coaches.
