Fitness level
Your VO2 max compared with people of your age and sex.
- Poor0-19th
- Fair20-39th
- Good40-59th
- Excellent60-79th
- Superior80-100th
Pace of Aging
No change vs. last weekUpdated weekly
- Resp
- SpO2
- RHR
- HRV
- Temp
Today’s high stress
0:15hrsvs. typical SatExcellent
62nd percentile for your age
Training load
0.86OptimalEstimates for personal insight, not medical advice.
What goes in
- VO2 max
- Your latest run value from the last 90 days; otherwise Fitbit’s latest daily estimate, marked Provisional.
- Age and sex
- From your profile.
How it is weighted
Pulse places your VO2 max in the FRIEND reference table (Kaminsky 2015): lab treadmill tests from 7,783 adults without heart disease, by sex and age decade. It reads between the published percentiles and keeps the result between the 5th and the 95th. Under 20 uses the 20-29 row; 80 and over uses 70-79. A man of 35 at 45.0 ml/kg/min sits just under the 60th percentile: Good.
What the bands mean
- 80th percentile and up
- Superior
- 60th-79th
- Excellent
- 40th-59th
- Good
- 20th-39th
- Fair
- Below the 20th
- Poor
Limits
Fitbit’s VO2 max is an estimate, while the table is lab-measured, so treat the percentile as approximate. The 2015 table runs 1.5-4.6 ml/kg/min higher than its 2022 update, so you may place a little low. The same table’s 75th percentile is the VO2 max reference in Pulse Age.
Sources
The full specification, with formulas, constants and worked examples, is fitness-level.md on GitHub. The code is tested against those examples.