Apple Watch VO₂ Max Not Updating? What to Check
Troubleshoot missing Apple Watch Cardio Fitness readings, check workout eligibility and Health permissions, and understand what My Bio Age can display.
By My Bio Age
If your Apple Watch VO₂ max is not updating, first check Cardio Fitness in Apple Health. My Bio Age reads the estimates stored there. It cannot make a missing watch measurement appear or generate a replacement from an indoor workout. Separating a missing source reading from an app permission problem makes troubleshooting much simpler.
1. Find the last original reading
In Health on your iPhone, open Browse, then Heart, then Cardio Fitness. Check the date of the latest result. An old value and an empty chart are different situations: an old value tells you a measurement was recorded previously, while an empty chart gives you no recent estimate to compare.
2. Check your workout type and setup
Apple's Cardio Fitness guide lists Outdoor Walk, Outdoor Run, and Hiking in the Workout app as activities used for these estimates. Indoor workouts do not count. An initial result can require at least 24 hours of wear plus several qualifying workouts and passive measurements. Recording a workout does not guarantee a new result every time.
Review the age, sex, height, weight, and heart-rate-affecting medication details used in your Health profile. Apple uses these when estimating cardio fitness. Keep them accurate; changing them to improve a displayed score defeats the purpose of tracking it. Do not change medication based on a watch value.
3. Check calibration if workout data also looks wrong
If distance or pace readings are unreliable as well, follow Apple's watch calibration instructions. These include checking Location Services and Motion Calibration & Distance, then walking or running outdoors at your usual pace for about 20 minutes in an open area with good GPS reception. Calibration supports workout measurements; it is not a promise that a VO₂ max estimate will immediately be produced.
4. If Health has data but My Bio Age does not
Review My Bio Age's read access to Cardio Fitness in Health, then reopen My Bio Age after the watch data has reached your iPhone. Check whether you are comparing the same date range. The app uses available history for its wellness calculations, so an old isolated measurement may not provide enough recent coverage for every score.
Our Apple Health data checklist explains how to separate source, permission, and history issues. Avoid deleting your Health history as an early troubleshooting step, and do not enter an invented VO₂ max just to fill a gap.
Does a missing result mean my fitness is worse?
No. A missing estimate tells you that a value is unavailable, not the direction of a fitness change. Once readings resume, review several observations and their dates before interpreting a trend. If a value concerns you, discuss it with a qualified healthcare professional; an estimated fitness number is not a medical assessment.
Where My Bio Age fits
My Bio Age brings available cardio fitness, recovery, sleep, and other Apple Health signals into one place on your iPhone. Its weekly MyBioAge Index™ is a wellness estimate, not a laboratory VO₂ max test or a clinical measure of aging. See how to check your wellness age estimate once your source data is available.
Once Cardio Fitness readings are available in Apple Health, explore how they fit your wider wellness picture. Download My Bio Age free on the App Store. The iPhone app is completely free, with no in-app purchases, subscription or account required. Your health data is processed privately on your iPhone.