The science.
Every call Ceiling makes comes from published research and your own data. Here's what it rests on.
HRV against your own normal
One low night is noise. A week below your own normal range, especially with resting heart rate rising, is a signal to back off. Ceiling compares you only to you.
Plews et al., 2013; Kiviniemi et al., 2007.
Mostly easy, some hard
Strong endurance athletes do most of their training easy and a small slice hard, and little in between. Ceiling shows where your time actually goes.
Seiler, 2010; Stöggl & Sperlich, 2014.
Load, fatigue and fitness
Every session adds load. Fitness builds slowly, fatigue fades fast. Ceiling tracks both from your heart rate and uses them to decide what today can absorb.
Banister, 1975; Gabbett, 2016.
The least that keeps fitness
Cut volume by up to two thirds and fitness holds, as long as intensity stays. That's where every Minimum comes from.
Hickson et al., 1985; Spiering et al., 2021.
Sleep is training
Short nights add up as debt, and a debt changes what you can absorb. Ceiling keeps the balance and tells you when to be in bed.
Van Dongen et al., 2003; Fullagar et al., 2015.