You can’t improve what you don’t track. It’s a phrase that’s echoed across industries and disciplines, and your personal fitness is no exception.
For most people, the go-to metric is weight. How much do I weigh? Am I too skinny? Too fat? But what does weight really tell us about our fitness? You can weigh a lot and be lean and strong, or weigh very little and still be metabolically unhealthy. The scale doesn’t capture the full picture—and it certainly doesn’t tell us how our body is performing.
About five months ago, I started using the Whoop device. After months of collecting data, I found myself deep in the numbers—curious about what they meant and how they could help me better understand my general physical preparedness (GPP). Through that process, three metrics have stood out: VO₂ max (maximal aerobic capacity), Resting Heart Rate (RHR), and Heart Rate Variability (HRV).
This article will focus on VO₂ max, what I have learned and what my progress has been with this biomarker.
VO₂ max (maximal aerobic capacity)
VO₂ max is a measure of how efficiently your body uses oxygen during intense exercise. The more oxygen your muscles can access, the more nutrients they can convert into ATP—the molecular fuel your body uses to move. In simple terms: a higher VO₂ max means better stamina and greater work capacity.
Put bluntly, it lets you go harder and longer during workouts. Woohoo!
Why VO₂ Max Matters
A good study on how VO2 max effects you can be found here:
| Title | Authors | Date |
|---|---|---|
| The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis | Scribbans TD, Vecsey S, Hankinson PB, Foster WS, Gurd BJ. | 2016 |
VO₂ max isn’t just about performance, it’s also a strong predictor of long-term health outcomes. In a 2016, Scribbans et al. found that VO₂ max strongly correlates with reduced risk of cardiovascular disease and all-cause mortality.
Here was their key takeaway:
“A minimal increase of just one metabolic equivalent (3.5 ml O₂·kg−1·min−1) was associated with a 10–25% improvement in survival.”
That’s a massive return for a small gain.
According to the same study, two types of training were found to significantly improve VO₂ max:
- Exercise programs of extended duration (think longer, steady-state cardio sessions)
- Repeated bouts of short-duration, high-intensity intervals (yep, interval training and CrossFit-style workouts)
A 2014 study looked at VO₂ max improvements in CrossFit athletes (“Physiological and performance effects of CrossFit”) and found some promising results, though the sample size was small (only 12 participants). It suggested that high-intensity functional training can impact VO₂ max positively as well, but the optimal combination of frequency, duration, and intensity is still up for debate something Scribbans et al. also noted.
What’s Considered “Good”?
The Cooper Institute has published benchmark VO₂ max data by age and sex. These values can help you gauge where you stand They are also good because VO₂ max is very contextual to age and sex.
Typical VO₂ Max Fitness Scores for Men by Age Group:
Typical VO₂ Max Fitness Scores for Women by Age Group:
What I like about Whoop is how accessible this information becomes. You can literally see the progress. Here’s what my VO₂ max has looked like since I started incorporating it into my training regimen (for context: I’m a 42-year-old male):
What’s interesting is how closely this lines up with what Scribbans and his team found. Over the past five months, I’ve been working closely with my coach to improve my aerobic capacity. The goal? Boost oxygen flow so I can do more work, recover better, and ultimately perform at a higher level.
Looking at this trend now, I can’t help but think—how cool would it have been to have this data a year ago? Even two years ago? It’s one thing to train hard, but having the data gives you the power to train smart.