Fitness enthusiasts are bombarded with numbers to track their progress – running speed, resting heart rate, and more. But one lesser-known metric, VO2 max, might be the king. This test measures how much oxygen your body absorbs during exercise, essentially gauging your aerobic engine’s size. 

Previously used primarily by elite athletes, VO2 max is now being touted as a valuable tool for everyone. Kate Baird, a specialist at the Hospital for Special Surgery in New York, calls it “the best piece of empirical information we have on health and longevity.” 

However, getting an accurate VO2 max reading requires an expensive and grueling test in a lab. Wearable devices offer estimates, but their accuracy is questionable. So, is knowing your VO2 max worth the time and money? 

What is VO2 Max? 

Think of VO2 max as a two-digit number reflecting your body’s oxygen metabolism efficiency. During exercise, your body craves more oxygen. The more efficiently you consume it, the more energy your muscles have, allowing you to exercise longer and harder. A higher VO2 max typically translates to sustaining aerobic activity for longer periods. 

The Test: Pushing Yourself to the Limit 

The VO2 max test involves exercising until exhaustion to determine your aerobic capacity. In a lab setting, with a specialized mask measuring inhaled and exhaled oxygen and carbon dioxide, participants push themselves to their absolute limit. It’s a tough test, costing hundreds of dollars, which can deter many. 

But why is it considered superior to other tests? Studies link higher VO2 max scores to a longer lifespan. While VO2 max naturally declines with age (around 10% per decade after 25), exercise can improve or maintain it. Research on middle-aged men and women showed even small amounts of activity boosted VO2 max, with moderate to vigorous exercise leading to even more dramatic improvements. 

Regular VO2 max tests, according to Baird, can indicate if you’re effectively slowing down the decline. It can also reveal if your training intensity or fueling needs adjustments. 

Alternatives to the Costly Test 

Not everyone can afford the time and money for a proper VO2 max test. This has led to wearable devices claiming to estimate VO2 max using heart rate and GPS data. However, the accuracy of these estimates is suspect, as the algorithms are not publicly available, according to Dimitris Spathis, a researcher at the University of Cambridge. 

Baird suggests alternative ways to set fitness goals. After all, the test might simply confirm what you already know about your fitness level. “The best predictor of performance is your performance,” she advises. Runners can set time or distance goals, while beginners aiming to be more active can start with short, manageable walks (10-15 minutes). Patience is key.