Rheostat: HRV & Recovery

Rheostat gives you one number each morning: how recovered you are, measured against your own baseline, never against population averages. It's free, every feature is included, and it runs on the Apple Watch you already own. WORKS WITH THE WATCH YOU HAVE Rheostat needs an iPhone on iOS 16 or later and an Apple Watch worn overnight: Series 4 or later, any SE, any Ultra. No new hardware, no particular model. If your watch records sleep and heart rate variability, that's everything the score is built from. READINESS (0 to 100) Your overnight heart rate variability, sleep, and resting heart rate, compared to your personal normal from the last 60 days. High means you can push. Low means ease off. Each metric can be tapped for a plain explanation of what it means and what moved it today. STRAIN (0 to 10) How much cardiovascular load you actually accumulated, read straight from your heart rate through the day. You don't have to record a workout for it to count. A long walk, an afternoon in the yard, a hike you never hit "start" on: they all score exactly the same as a logged session if they kept your heart rate up. Straight about what it can't do: Strain measures cardiovascular load. A heavy lifting session at a low heart rate scores low, and that's correct. Heart rate can't see mechanical load, and no wrist-based score can. We'd rather tell you that up front. HONEST BY DESIGN Plenty of recovery apps cluster everyone in the 90s because a high number feels good. That makes the score useless. If it's always green, it's telling you nothing. Rheostat is built to be right rather than flattering. If your recovery is mediocre, it says so. YOUR HISTORY, FROM DAY ONE Rheostat builds your baseline from the Apple Health history already on your iPhone. If you've worn a watch for a while, you get real scores immediately instead of waiting weeks. NOTHING LEAVES YOUR IPHONE No accounts. No servers. No analytics, no tracking, no advertising. Rheostat makes no network requests at all. You can run it in Airplane Mode and every feature works. Your health data is read from Apple Health, processed on your iPhone, and stored only on your iPhone. FREE, WITH A TIP JAR There is no subscription, no trial, and nothing held back. If Rheostat earns a place in your mornings, there's an optional tip jar in Settings. A tip changes nothing in the app. ALSO INCLUDED • Workout analysis with effort, heart rate zones, and heart rate recovery • Seven-day and thirty-day trends for every metric • A glossary and in-context explainers for every number • Optional morning notification with your score WHAT IT NEEDS An Apple Watch worn to sleep. Readiness needs overnight HRV and sleep; without them there's nothing meaningful to measure. Rheostat reads: date of birth, heart rate variability, resting and workout heart rate, heart rate recovery, sleep, sleeping wrist temperature, respiratory rate, steps, exercise minutes, active energy, workouts, and VO2 max. NOT A MEDICAL DEVICE Rheostat is for general wellness and fitness only. It cannot diagnose, treat, or prevent any condition, and should never be used to make a medical decision or to delay seeking care. If you feel unwell, talk to a doctor, not an app. Help: rheostat.app/help Privacy: rheostat.app/privacy