Strain
How much load you have put on your body today.
What it is
Strain is the counterweight to Recovery: it measures how much load you have taken on today. It climbs as you move and train, and it is scored against what a genuinely hard day looks like for you.
How we calculate it
We use your total daily active energy, workouts plus all-day movement, measured against a personal reference for a hard day. The curve flattens toward the top, so a single workout reads high on its own and a full hard day lands near, but not pegged at, 100.
Your morning Recovery sets a suggested Strain target: a strong recovery invites a harder day, a low one nudges you toward rest.
Sources
The published research and guidelines this number leans on.
- World Health Organization 2020 guidelines on physical activity and sedentary behaviourBull FC et al. (2020) · British Journal of Sports Medicine 54(24):1451-1462
- Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoringPlews DJ et al. (2013) · Sports Medicine 43(9):773-781
Last updated 27 August 2026.