Health Score Apps: Understand Your Body with One Number
Every night, your wearable quietly collects thousands of data points. Steps, heart rate, sleep stages, HRV, blood oxygen, skin temperature. Raw data is hard to act on, though. Health score apps turn all of it into a few simple numbers you can actually use. Here are the six scores worth knowing about.
The short version
Six numbers can turn all that sensor data into a daily plan. Sleep shows how well you recovered. Strain and recovery tell you whether to push or take it easy. Body battery is a live read on your energy. VO₂ Max and fitness age track how you improve over the course of months.
Sleep Score: the one that rules them all
Your sleep score combines duration, sleep stages, consistency, and overnight heart rate. A good score is 80 or above. If you only track one metric, track this one. Bad sleep drags down everything else.
Strain Score: how hard your body actually worked today
Strain measures your total daily load, not just workouts but everything. Walking to get coffee. Standing in line. Chasing your dog. The scale runs 0 to 21. Most active people live between 12 and 16. At 10 on a training day, you left gas in the tank. At 17 on a rest day, you didn't actually rest.
Recovery Score: are you ready, or just stubborn?
Recovery combines your overnight HRV, resting heart rate, and sleep quality into a single readiness percentage. The colors below cover most of it. The part people miss is that when the score reads red and you still feel fine, the score is usually right. By the time the tiredness catches up with you, you've been overdoing it for days. It's worth listening to the number before your body forces you to.
Body Battery: a fuel gauge for humans
Body battery tracks your energy in real time, updating all day. It drops with activity and stress. It recharges with sleep and rest. Check it before committing to that 6 PM workout. At 25%, maybe save the HIIT class for tomorrow.
VO₂ Max: your slow-motion health report
VO₂ Max measures how efficiently your body uses oxygen, but you should always read it against your age. A score of 40 might be great at 60 but below average at 25. Unlike a sleep score, which changes every night, VO₂ Max reflects months of consistent training, so age-adjusted numbers are the only meaningful way to read it.
| Age | Below Avg | Fair | Good | Elite |
|---|---|---|---|---|
| 20–29 | <38 | 38–42 | 43–48 | 49+ |
| 30–39 | <34 | 34–38 | 39–44 | 45+ |
| 40–49 | <30 | 30–34 | 35–40 | 41+ |
| 50–59 | <26 | 26–30 | 31–36 | 37+ |
| 60+ | <22 | 22–27 | 28–33 | 34+ |
Based on women's norms. Men average 3–5 points higher per tier. Values shown in ml/kg/min.
Fitness Age: the score you actually want to brag about
Fitness age combines VO₂ Max, resting heart rate, activity, and body composition into one number. If you're 45 and your watch says your body performs like a 35-year-old, that's a good sign. The bigger the gap between your calendar age and your fitness age, the better. People enjoy this score because it's encouraging: it shows you're not just tracking your health, but actually improving it.
Get all 6 health scores, free on CareDevi.
Sleep, strain, recovery, body battery, VO₂ Max, and fitness age. Reads from 500+ wearables. Free core app.
Get Started Free →Also see: Fitness Challenges → compete with friends and climb the leaderboard.