This Wearable Data Reveals the Training Strategies That Improve VO2 Max the Most

If you have a fitness watch, you probably regularly get updates on your VO2 max. While historically not as accurate as lab-based tests, experts say watch data can help you get a sense of general trends. (Is your VO2 max improving over time… or not?)But zoom out beyond your own stats and consider that wearables have access to data from thousands of users. And that data gives us insights into larger-scale trends about what actually improves our fitness.So we dug into data from Apple Watch and Coros users to find out what factors influence fitness, particularly VO2 max the most. Here’s what to know.More Volume, Higher VO2 Max? Data from both Apple Watch and Coros suggests that overall volume plays a role in VO2 max changes, as more time on your feet can boost your overall fitness level. While not the number-one strategy experts recommend to increase your VO2 max, specifically, volume affects durability, which is how well your VO2 max, lactate threshold, and running economy hold up over a long distance like a marathon, says Michael Joyner, MD, a professor at the Mayo Clinic in Minnesota.That could help explain why participants in the Apple Heart and Movement Study with “above average” cardio fitness (or VO2 max) levels also averaged more than 200 minutes of activity per week while those with “high” VO2 max averaged more than 300 minutes of activity per week. And, those with higher VO2 max levels exercised more than 15 minutes longer per day than those with lower levels, on average.This also tracks with Coros data of North American users, pulled specifically for Runner's World, which shows an association between running four days a week and a 0.1 percent change in VO2 max over 12 weeks, and an association between running six days per week and a 0.4 percent change.Similarly, running 40K to 60K (about 25 to 37 miles) per week in the same time period was associated with a 0.2 percent change in VO2 max; upward of 100K, or 62 miles, led to a 0.5 percent change. In practical numbers, that could mean going from a VO2 max of 50 to a VO2 max of 50.25. That might not seem like a lot, but it could translate to meaningful performance improvements, like making running feel easier and clocking a faster pace.In fact, Coros users made pace improvements running less than 13 miles per week, going from an average of 17:06 pace to 15:04 pace over 12 weeks. But running 50 miles or more per week led to an easy run pace improvement of 13:21 pace to 10:04 pace.The weekly long run itself seemed to have an influence, too. Those who ran 15K or more in one go had roughly a 0.2 percent improvement in VO2 max, compared to running less than 15K, which led to a 0.1 percent increase at best.Both Apple and Coros estimate VO2 max based on the relationship between heart rate and running pace during outdoor runs.The Training Strategies That Improve VO2 Max the Most While overall volume can help, Joyner says there’s a particular type of workout that’ll have the most measurable impact on both VO2 max: “The single most important thing people can do is what's called long intervals, which are three- to five-minute efforts at roughly 5K race pace,” Joyner says, adding that this could look like five three-minute efforts or six reps of 800 meters with two to three minutes of light jogging in between a couple times per week.“You want to do them hard where you really feel like you've pushed yourself, but you want to have what we described as the ‘no-bend-over rule,’” he says. “If you have to bend over when you're done, you've gone too fast.”Here’s why they work: These intervals stimulate the heart, improving cardiac output and stroke volume, Joyner explains, as well as helping the muscle to better use oxygen, stimulate mitochondria for better energy production, and increase capillaries. This all allows oxygen to more efficiently reach your working muscles, making exercise feel easier and boosting your overall fitness.The other key workout for improving VO2 max, Joyner says, is the threshold run, which would be at about 80 or 90 percent of your 10K pace. Indeed, per the Coros data, the most effective way to increase VO2 max involved threshold workouts with users increasing their VO2 max by an average of 0.6 percent over 12 weeks with this type of workout.Apple data also shows an association between progressive and “challenging” training and an increase in VO2 max, which suggests that the metric is influenced by factors beyond sheer easy running.Why It’s Helpful to Keep Tabs on VO2 MaxJoyner points out that many variables, including age, genetics, and sex, play a role in your VO2 max number. Per Apple data, participants were more likely to improve their cardio fitness by more than 1 mL/kg/min if they were male, at a lower fitness level to start, and younger than 30 years old, for example.But even with those variables in mind, and looking beyond the data on your watch or going to a lab for a VO2 max assessment, Joyner says there are other subjective and objective signs your VO2 max is going up, specifically perceived effort and race results.“Are you running the same speed and does it feel a little bit easier? Are you running faster and it feels equally hard? And what’s happening with your race results?” he asks. “It’s really easy to get caught up in these metrics, but when push comes to shove, you’re running faster or not.”General upticks in your fitness level offer benefits beyond running speed, too. For one, it can help you run slower distances with less perceived effort. And beyond fitness, high VO2 max is associated with reducing your risk of diseases ranging from diabetes to cancer to heart disease, and with a lower risk of all-cause mortality.