If you’re serious about endurance sports, especially marathon running, you’ve probably heard of VO2 max. But what exactly is it? How does it affect performance? And more importantly, how can you improve it?
In this guide, we’ll break down the science of VO2 max, its importance for marathon runners, how it relates to your lactate threshold, and the best wearables that measure VO2 max.
What Is VO2 Max?
VO2 max stands for maximal oxygen uptake or maximal aerobic capacity. It refers to the maximum amount of oxygen your body can utilize during intense exercise. It is typically expressed in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min).
In simple terms, the higher your VO2 max, the more oxygen your body can use, which translates to better cardiovascular fitness and aerobic endurance.
The Science Behind VO2 Max
VO2 max is determined by several physiological factors:
- Cardiac output: How much blood your heart pumps per minute.
- Hemoglobin levels: Your blood’s ability to carry oxygen.
- Mitochondrial density: The number of mitochondria in your muscle cells, which produce energy (ATP).
- Capillary density: More capillaries mean more efficient oxygen delivery to muscles.
During aerobic exercise, your muscles need oxygen to produce energy. The more oxygen your body can transport and use, the better your performance—especially in endurance events like marathons and ultramarathons.
Why VO2 Max Matters for Marathon Runners
For marathon runners, VO2 max is a key performance indicator. It doesn’t just reflect how fit you are—it determines how fast and how long you can run before fatigue sets in.
VO2 Max and Race Pace
A runner with a higher VO2 max can sustain faster paces for longer because their body is more efficient at using oxygen. Elite marathoners often have VO2 max values above 70 ml/kg/min.
However, VO2 max alone doesn’t determine race success. Two runners with similar VO2 max levels can perform very differently depending on other factors like running economy and lactate threshold (we’ll touch on this shortly).
VO2 Max and Recovery
Higher VO2 max also improves recovery. Your cardiovascular system becomes more efficient at clearing lactate and delivering nutrients to tired muscles, which is crucial during long runs or back-to-back training sessions.
How to Improve Your VO2 Max
Improving your VO2 max involves consistent training that challenges your cardiovascular system.
1. High-Intensity Interval Training (HIIT)
HIIT sessions—such as 4×4 minutes at 90-95% of your max heart rate—are highly effective in improving VO2 max. They force your body to adapt to high oxygen demands.
2. Tempo Runs
While not as intense as intervals, tempo runs (at or slightly below your lactate threshold) help increase the intensity you can sustain aerobically.
3. Long Runs
Weekly long slow distance (LSD) runs build endurance and enhance your body’s ability to use oxygen over prolonged periods.
4. Altitude Training
Training at high altitudes increases red blood cell production, which improves your blood’s oxygen-carrying capacity. This adaptation can elevate VO2 max when you return to sea level.
VO2 Max and Lactate Threshold: The Crucial Relationship
VO2 max tells you your aerobic potential, but your lactate threshold determines how much of that potential you can actually use during a race.
While VO2 max might remain stable, your lactate threshold can improve significantly with training—allowing you to run faster without fatiguing. For an in-depth explanation, check out our lactate threshold article.
In short:
- VO2 max = Your aerobic ceiling.
- Lactate threshold = Your race pace.
Both are critical for marathon performance.
Wearables That Accurately Measure VO2 Max
Many modern fitness trackers and GPS watches estimate VO2 max using heart rate and running speed algorithms. Here are some of the best devices:
Garmin Watches
Models like the Garmin Forerunner 265, 965, and Fenix 7 series provide estimated VO2 max along with training status and recovery insights.
Apple Watch
The Apple Watch Series 6 and newer offer VO2 max readings under the name “Cardio Fitness” using heart rate and motion data.
Huawei GT watches
Huawei GT lineup devices such as Huawei GT 5 and Huawei GT 5 pro are some of the best smart watches in the market. They are cheaper in price, can pair with both android and IOS, and are very accurate.
Scientific review suggest that they accurately predict your V02 max very close to lab values.
Pro tip: Wearables use predictive algorithms. For more accurate results, consider a lab-based VO2 max test involving a treadmill and gas exchange analysis.
Other Key Information About VO2 Max
- Age and VO2 Max: VO2 max tends to decline with age, but regular training can slow this process.
- Gender Differences: Men generally have higher VO2 max values due to larger hearts and more hemoglobin, but trained women can still achieve elite levels.
- Genetics: Your genes influence baseline VO2 max, but with training, most people can improve by 15–20%.
Final Thoughts
Understanding and improving your VO2 max can significantly boost your endurance performance. For marathon runners, it’s a crucial metric, tightly linked to lactate threshold, running economy, and overall race potential.
Use VO2 max wearables, train smart with a mix of HIIT, tempo runs, and long runs, and monitor your progress over time.
