SOURCES & METHODOLOGY
Understanding FinchQ Functional Age™
Walking-based physical function, viewed in age-related context.
Function in age-related context
FinchQ Functional Age™ is a walking-based wellness estimate that puts measured physical function into age-related context. Walking speed is the foundation of this estimate; it is not a complete assessment of everything you can do.
It measures the function we can observe—not every process that helped produce it.
Biology, health, practice, environment, confidence, and habits can influence walking performance. Observing the outcome does not let FinchQ separate or directly measure all those influences.
Different ages answer different questions
Chronological age
How much time has passed since birth? This is your age in calendar years.
Biological age
How do selected biological markers compare with age-related patterns? The answer depends on the biomarkers and model used; there is no single universal measure.
Health age
How does a particular model summarize selected health information in age terms? Its meaning varies across products and methods.
Functional age
How does performance in a defined functional domain compare with age-related patterns? Its meaning depends on which function is measured.
FinchQ Functional Age™
How does your observed walking performance fit FinchQ’s age-related reference framework? This is a walking-based wellness interpretation, not a measure of biological age or a clinical determination of age.
These concepts are not interchangeable. A walking-based estimate cannot establish the age of your organs or how long you will live.
Where the information comes from
FinchQ reads qualifying walking-speed information from Apple Health with your permission. These mobility recordings normally come from an iPhone carried during everyday walking. Permission alone does not create data.
Apple Watch is optional and adds supported information elsewhere in FinchQ. This walking-based estimate depends on qualifying iPhone mobility recordings. An iPad alone may not supply the information it needs.
An unavailable result means there isn’t enough data. “Waiting for Health data,” “Learning,” or an unavailable value means FinchQ does not yet have enough qualifying information to produce that view. It does not establish that your function is poor.
From walking recordings to an estimate
1. Use a stable observation window
The stable estimate uses the preceding 28 complete days of qualifying iPhone walking-speed data, keeping measurement sources separate.
2. Require enough observations
A qualifying day needs at least five retained readings. The profile needs at least ten qualifying days and fifty retained readings overall.
3. Balance the days
FinchQ calculates a median for each qualifying day, then the median of those daily medians. This keeps a day with many recordings from dominating simply because it contains more samples.
4. Place performance in peer context
Age- and sex-related walking-speed reference patterns provide comparison context.
5. Apply FinchQ’s age interpretation
The 35th–65th percentile range is neutral. Outside that range, FinchQ’s proprietary rules adjust the age estimate, with the adjustment capped at four years younger or older than chronological age.
The separate weekly insight uses shorter comparison windows to describe recent change. It can change before the stable 28-day estimate does. These views describe different time scales.
What the reference research contributes
The reference framework draws on published daily-life walking-speed research using the Watch Walk method and UK Biobank data. That research describes age-related walking patterns; it does not validate FinchQ’s conversion to a Functional Age.
The research used wrist-derived measurements. FinchQ uses qualifying Apple Health iPhone walking-speed recordings. Measurement methods, study populations, and everyday walking conditions can differ, so these comparisons provide approximate wellness context.
Research norms describe a particular population and age range. Comparisons outside that population are less certain. A reference percentile describes where a measurement falls within the comparison framework; it is not a grade for your life or a clinical finding.
What a younger or older result means
A younger result means your observed walking-speed pattern falls on the more favorable side of FinchQ’s reference framework. An older result means it falls on the less favorable side. Neither result establishes accelerated or reversed biological aging.
For example, a chronological age of 60 and a FinchQ Functional Age™ of 58 describes this model’s interpretation of walking performance. It does not establish that the person’s body is biologically 58.
Use changes as a reason to examine context: Are you carrying the phone consistently? Has your routine changed? Are pain, illness, fatigue, or confidence affecting your walking? Do everyday activities feel different?
Boundaries of the estimate
This estimate does not directly measure muscle strength, reactive balance, endurance, cognition, organ function, or the safety of living independently. Walking speed is informative, but physical function is broader.
The percentile-to-age transformation, neutral band, and four-year cap are FinchQ design choices. They are not a clinically validated biological-age conversion or an individual prognosis.
Sources & methodology notes
These references provide walking-measurement and age-related research context. They do not, by themselves, validate FinchQ’s proprietary Functional Age conversion.
Chan and colleagues: Daily-Life Walking Speed, Quality and Quantity Derived from a Wrist Motion Sensor (2024)
Provides age-related reference data from daily-life walking research. The study’s wrist-derived measurements differ from the iPhone measurements used by FinchQ.
Apple: Measuring Walking Quality Through iPhone Mobility Metrics
Explains the development and validation of Apple’s walking measurements. It does not validate FinchQ’s age conversion.
Studenski and colleagues: Gait Speed and Survival in Older Adults (2011)
Provides research context for walking speed. Population associations are not an individual prognosis.