VO₂max: What It Is, Why It Matters, and How It’s Measured

To decode this term, VO₂max is the maximum rate of oxygen consumption possible during bouts of physical exertion, measured in milliliters of oxygen per kilogram of body weight every minute (mL/kg/min).

VO₂max is how well your body can take in, transport, and use oxygen during exercise. Oxygen is required to produce energy aerobically, so VO₂max reflects how efficiently your heart, lungs, blood vessels, and muscles work together under physical stress. In clinical physical therapy and wellness settings, this information provides meaningful insight into overall cardiovascular and metabolic health.

Physician and longevity researcher Peter Attia is the loudest voice regarding this public discourse. He frequently highlights VO₂max as one of the most important measurable predictors of long-term health and lifespan. Individuals with higher aerobic fitness tend to live longer and maintain physical independence later into life. From a health standpoint, VO₂max is more than a performance metric. Research has consistently shown that higher aerobic capacity is strongly associated with lower risk of cardiovascular disease, metabolic disease, and early mortality, outcomes that are highly relevant in preventative care and rehabilitation.

To further understand why VO₂max is meaningful, it helps to understand how it is measured. True VO₂max testing is performed during a graded exercise test, typically on a treadmill or stationary bike. As exercise intensity gradually increases, the individual breathes through a mask connected to a metabolic analyzer. This system measures how much air is inhaled and exhaled, along with the concentrations of oxygen and carbon dioxide in each breath. Using these respiratory gas measurements, the test directly calculates how much oxygen the body is consuming at each workload.

This type of testing is considered the gold standard because it measures oxygen use directly, rather than estimating it - making it especially valuable in clinical and physical therapy environments like Tula Physical Therapy & Wellness in Union Square, NYC.

As exercise intensity increases, oxygen uptake rises until it reaches a point where it no longer increases despite additional effort. That point represents maximal aerobic capacity. In addition to VO₂max itself, respiratory gas analysis provides insight into breathing efficiency and how the body transitions between lower and higher intensity exercise, key data points for rehabilitation, endurance training, and personalized exercise programming.

Many people are familiar with estimated VO₂max values provided by wearable devices or fitness apps. These estimates are calculated using heart rate, pace, or workload formulas. While they can be useful for tracking general trends, they are influenced by factors such as hydration, caffeine intake, sleep quality, stress, medications, and individual heart rate variability. As a result, indirect estimates can be inaccurate and may not reflect true aerobic capacity.

Direct respiratory gas measurement removes much of this uncertainty. Because it measures oxygen utilization at the cellular level, it provides objective data that is not dependent on prediction equations. This makes it particularly valuable in a physical therapy and wellness clinic, where precision matters and individual differences are significant. It also allows for more personalized interpretation rather than relying on population averages.

Importantly, VO₂max is not fixed. It is highly trainable, especially in individuals who are not already highly conditioned. Measuring VO₂max allows clinicians and coaches to establish a clear baseline, track progress over time, and determine whether training interventions are producing meaningful physiologic change. Without objective measurement, improvements are often assumed rather than confirmed.

Understanding what VO₂max is and how it is measured provides valuable insight into cardiovascular health. Knowing your aerobic capacity helps clarify where you are starting and how your body responds to physical stress. At Tula Physical Therapy & Wellness in Union Square, NYC, VO₂max testing supports a more informed, data-driven approach to cardiovascular training, rehabilitation, and long-term health. Stay tuned in for further discussion on how much cardiovascular training is required, and how it should be structured to improve VO₂max efficiently.

Disclaimer: This information is meant for educational purposes and does not supersede or replace direct medical advice from your physician or healthcare provider.

References:
American College of Sports Medicine. (2021). ACSM’s guidelines for exercise testing and prescription (11th ed.). Wolters Kluwer.

American Physical Therapy Association. (2020). Physical therapist clinical practice guidelines for promoting physical activity and exercise across the lifespan. Physical Therapy & Rehabilitation Journal, 100(10), 1773–1786.

Attia, P., & Gifford, B. (2023). Outlive: The science and art of longevity. Harmony Books.

Jamieson, J. (2011). MMA conditioning. Human Kinetics.

Ross, R., Blair, S. N., Arena, R., Church, T. S., Després, J. P., Franklin, B. A., Haskell, W. L., Kaminsky, L. A., Levine, B. D., Lavie, C. J., Myers, J., Niebauer, J., Sallis, R., Sawada, S. S., Sui, X., & Wisløff, U. (2016). Importance of assessing cardiorespiratory fitness in clinical practice: A case for fitness as a clinical vital sign. Circulation, 134(24), 653–699.

Poole, D. C., Wilkerson, D. P., & Jones, A. M. (2008). Validity of criteria for establishing maximal O2 uptake during ramp exercise tests. European Journal of Applied Physiology, 102(4), 403–410.

Seeley, S., Johnston, S., & House, S. (2019). Training for the uphill athlete: A manual for mountain runners and ski mountaineers. Patagonia Books.