Garmin Fitness Age, how to lower it, and is WHOOP Age Better?
This article shows how your fitness age is a key factor determining how long you will live. More importantly, the concept of Healthspan includes biological factors to say how much of your future life could be healthy.
You will be pleased to know that there is (almost) a magic bullet for living a long and healthy life. In fact, there are two: get fitter and lose fat. You can easily measure these with Garmin wearables and tech.
VO₂ max is the key metric, combining your fitness ability and weight in one number. Along with other factors, Garmin uses these to calculate your Garmin Fitness Age. Here’s how to achieve the minimum score.
Understanding the Metrics: Fitness Age, Chronological Age, and Health Age
We all age differently, and your birth date (chronological age) is often inadequate to measure your physiological state. This mismatch has led to the development of several age measurement concepts, including fitness age, biological age, and health age. All quantify your true physiological state relative to the years lived.
- Chronological Age: How long you have been alive.
- Biological Age or Health Age: Considers medical-grade biological markers of ‘damage’ that correlate to all-cause morbidity.
- Fitness Age: Your VO₂ max compared to someone of the same age and sex.
Garmin Fitness Age: Calculation and Interpretation
Garmin’s Fitness Age estimates how fit you are compared to your age group, to a person of the same gender and actual age. It is primarily an interpretation of your VO₂ max estimate. VO₂ max measures the maximum volume of oxygen your body can import, transport, and use during intense activity in one minute—the gold standard for assessing cardiorespiratory fitness.
- Likely calculation: Your VO₂ max will be compared to your age group’s normal distribution of VO₂ max. This and other factors will produce an adjustment to your chronological age.
- Calculation Components: The core calculation uses VO₂ max. Newer Garmin smartwatches enhance this calculation by factoring in activity intensity, resting heart rate, and body fat percentage (if using a Garmin Index smart scale) or BMI.
- Interpretation: If your fitness age is lower than your chronological age, it indicates a good fitness level.
- Errors: Your age and weight must be correctly set. Garmin Index scales estimate fat using Bioelectrical Impedance Analysis, which is prone to inaccuracy.
Q: What is a good Garmin fitness age?
A: Any value lower than your chronological age is good. Ten years lower is very good.
Garmin has changed the method used to calculate Fitness Age. Before 2022, a VO₂ max of around 50 resulted in a minimum Fitness Age of 20. It seemed that Garmin used the age at which the average person’s VO2max matches your VO₂ max and assumed you had that fitness age. While that makes some sense, a 65-year-old could have a fitness age of 20, which is meaningless. That is why it was changed.
Example: I had a fitness age of 20 with the old method. With the new calculation, I get a discount of 10 years below my chronological age. This might be the maximum. Let me know if yours is better! Some scientific measures give discounts of 12 years. Garmin might match those.
Comparison: Garmin Fitness Age vs. WHOOP Age
Whilst Garmin’s concept of a fitness age is a good one, it will only go part of the way to determining how many years of healthy life you have to look forward to—your healthspan (as opposed to your lifespan, which can include ‘poor’ years).
WHOOP tries to assess your Biological Age (Health Age). This is more of a medical-grade definition that describes the accumulation of damage at the molecular, cellular, tissue, and organ levels, adversely affecting vitality and functions. Biological age measures are crucial because they correlate strongly with adverse health outcomes like all-cause mortality, cardiovascular events, and functional decline. A good body of science supports these measures; however, they rely on data that can be tricky or impossible for a wearable to collect.
- Measurement: Biological age can be quantified using complex methods such as DNA methylation (the epigenetic clock) or composite biomarker predictors like the Levine PhenoAge model, which uses blood-measured biomarkers.
- WHOOP Age: WHOOP Age is assessed based on sleep duration and consistency, steps, heart rate zone minutes, strength activity, VO₂ max, resting heart rate, and lean body mass. In October 2025, WHOOP started to roll out its panel of 65 blood measurements, including Albumin, glucose, and others used in the medical-grade definition of Health Age. WHOOP will fine-tune its WHOOP Age metric to approach medical-grade definitions.
While Garmin Fitness Age and WHOOP Age aim to provide a score reflecting physiological health separate from chronological age, they rely on different primary metrics and goals.
| Feature | Garmin Fitness Age | WHOOP Age (Physiological Age) |
| Primary Metric | VO₂ max, representing cardiorespiratory fitness. | A calculation based on nine key health metrics over six months. |
| Key Factors | VO₂ max, activity intensity, resting heart rate, BMI/body fat percentage. | Sleep duration/consistency, resting heart rate, VO₂ max, lean body mass, steps, and time in heart rate zones. |
| Pros | Based on VO₂ max, a robust indicator associated with a reduced risk of diseases and improved longevity. Easily accessible through the Garmin Connect app. | Incorporates diverse physiological data (sleep, body composition, activity) for a holistic “physiological age.” Provides actionable Healthspan insights. |
| Cons | VO₂ max estimation can be sensitive to activity types. | Slow-moving metric that will not change drastically day-to-day, requiring long-term habit change. |
| Goal | To estimate fitness level compared to peers. | To make long-term health actionable by showing how daily choices affect physiological age. |
Strategies to Lower Your Garmin Fitness Age
Lowering your Garmin Fitness Age focuses on optimising key physiological markers used in the calculation, particularly cardiorespiratory fitness (VO₂ max), resting heart rate, and body composition. Improving your fitness level to exceed what is expected for your chronological age group offers a huge benefit, potentially greater than known medical treatments.
- Improve Cardiorespiratory Fitness (VO₂ Max): VO₂ max is the fundamental metric. Regular physical activity can slow or reverse age-related declines in cardiorespiratory fitness.
- Exercise Intensity: Exercise recommendations for lowering fitness age include striving for at least five vigorous intensity minutes within a 30-minute workout. Vigorous intensity is typically defined as an activity where it is difficult to speak.
- Guidance: Garmin Coach offers adaptive plans for running, cycling, or strength training, which can help structure workouts to improve fitness.
- Reduce Resting Heart Rate: A lower resting heart rate indicates better cardiovascular health. This can be achieved by:
- Prioritising regular exercise.
- Maintaining a healthy weight.
- Avoiding tobacco.
- Reducing stress, which can be monitored using Garmin’s all-day stress tracking feature.
- Resting Heart Rate will fall if VO2max increases.
- Manage Body Composition: Newer devices factor in body fat percentage or BMI. Since VO₂ max is calculated relative to body weight (per kilogram), losing body fat will increase your VO₂ max score, lowering your fitness age. This goal usually requires combining exercise with dietary changes.
- Data Accuracy: Ensure your user profile includes accurate information such as your birthdate, height, and weight, to allow for the most accurate fitness age calculation.
Independent research (citations below) confirms that high physical fitness levels preserve functional abilities and decelerate biological ageing. For those whose fitness age significantly exceeds their chronological years (15% or more below average VO₂ max), the risk of dying prematurely is substantially higher.
Take Out
New Age measures like Garmin Fitness Age are a good way of restating more technical terms like VO2max, so anyone can understand them. The strategies are highly similar, whether you want to improve your Fitness Age or Healthspan.
From this article, you can understand the calculations Garmin makes and work on improving the component scores. However, at least for Garmin’s Fitness Age, you need to get fitter and lose fat.
Increasing your Healthspan is probably more important, but it relies on medical-grade test results, which are difficult or costly to obtain as a full panel. That’s where Whoop’s 65 biomarkers taken from blood tests promise to take the consumer-grade understanding of healthspan to the next level.
Sources:
- Garmin Fitness Age main page
- Compatible Devices
- VO₂ Max and Lifestyle
- Fitness Age vs. Chronological Age:
- Physical fitness age (from grip strength, walking speed, balance) outperforms chronological age in sarcopenia detection; linked to obesity, hyperglycemia. PubMed (2022)
- Non-exercise model of cardiorespiratory fitness predicts long-term mortality. PMC (2023)
- VO₂ max-based fitness age predicts mortality 82% better than chronological age in 5,000 adults. PubMed (2014) (Corrected Link)
- Health Age vs. Chronological Age:
- PhenoAge (biological) predicts ICU mortality superior to chronological age; tied to comorbidities. PMC (2023)
- Epigenetic clocks (DNAmAge) forecast morbidity/mortality beyond chronological age via biomarkers. PMC (2018)
- Biological age via hallmarks (e.g., inflammation, epigenetics) better estimates vascular ageing than chronological. JACC (2020)
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For my last two birthdays Garmin has increased my fitness age by only half a year. As of now, 70 minus 58 is 12 🙂
(watch was Venu 2 until recently, now Venu 4)
i hear 12
do we hear 13?
(PS well done 🙂 )