My Bio AgeMy BioAge

Methods & Sources

My Bio Age turns Apple Health metrics into two headline numbers: Fitness Age and Biological Age. We lean on peer-reviewed research, transparent weightings, and conservative assumptions so you can see what’s changing and why.

Fitness Age

Fitness Age is powered by VO₂max, which Apple Watch measures during eligible outdoor workouts. We compare your VO₂max to the FRIEND normative database based on age and biological sex. The resulting percentile is mapped to the age where that percentile is average.

  • VO₂max samples are filtered for recency and workout quality.
  • We smooth spikes with an exponentially weighted moving average to resist short-term noise.
  • Weekly digests highlight improvements or declines compared to the prior week.

Biological Age

Biological Age blends multiple recovery and cardiovascular metrics into a single z-score that is then translated into an age scale. The components and directions:

  • VO₂max (higher is younger)
  • Heart-rate variability SDNN (higher is younger)
  • 1-minute heart-rate recovery post workout (higher is younger)
  • Resting heart rate (lower is younger)
  • Walking heart rate (lower is younger)
  • Sleep duration & sleep efficiency (higher is younger)

Each metric is standardized against your personal long-term average and population norms. Weightings adapt based on signal availability: if VO₂max is missing, the remaining metrics expand to maintain sensitivity without exaggeration. Weekly digests explain which metrics had the largest impact on your score.

Caveats

Apple Watch VO₂max is an estimate derived from outdoor exercises that meet Apple’s criteria. Accuracy depends on workout conditions, motion, and consistent wear. We flag missing or low-confidence samples so you know when to repeat a measurement. Biological Age is a wellness indicator, not a medical diagnosis.

References