Biomarker Database

Cardiorespiratory fitness

VO2 max

VO2 max estimates the body's capacity to use oxygen during intense exercise.

What it measures

VO2 max estimates maximal oxygen uptake during intense exercise. It is one of the clearest markers of cardiorespiratory fitness and functional reserve.

How it is measured

Best measured with cardiopulmonary exercise testing; commonly estimated by wearables, fitness tests, or submaximal protocols.

What it is useful for

  • Tracking aerobic fitness and training response.
  • Understanding functional reserve across aging, illness, and recovery.
  • Guiding endurance training zones when measurement quality is reliable.

How to interpret it

Higher usually means better reserve

Higher cardiorespiratory fitness is consistently associated with better health outcomes, though individual interpretation depends on age, sex, health status, and test quality.

Wearables estimate, labs measure

Wearable VO2 max can be useful for trend tracking, but clinical cardiopulmonary exercise testing is more precise.

Trainability is the opportunity

Aerobic base training, intervals, weight management, and consistency can improve VO2 max for many people.

What can move the signal

  • Regular moderate-intensity aerobic training.
  • Periodic higher-intensity intervals when medically appropriate.
  • Resistance training to support movement economy and muscle function.
  • Progressive training load with enough sleep and recovery.

Important cautions

  • People with chest pain, unexplained shortness of breath, fainting, or known heart disease should ask a clinician before intense testing or training.
  • Wearable estimates can shift because of device algorithms, terrain, heat, fatigue, and sensor quality.
  • Do not compare your number directly to someone with a different age, sex, sport background, or health context.

Use this inside a system

A biomarker becomes useful when it connects to a decision: retest timing, training load, nutrition changes, sleep quality, medication discussion, or clinical follow-up. Aeonvera is built to place each signal in context with your labs, wearables, protocols, and physician-ready notes.

Read the healthspan strategy guide

References and further reading

  1. American Heart Association: target heart rates and exercise intensity
  2. AHA journal: cardiorespiratory fitness reference standards
  3. VO2 max in clinical cardiology review