Smartwatches from tech companies like Apple and Garmin make it easy to see a number that might reflect how old you are more accurately than the number of birthdays: VO2max, the maximum amount of oxygen your body can use during intense exercise.
The higher your VO2max, experts say, the better your cardiovascular fitness and potentially the longer your life. In the past, only serious athletes sought out a traditional VO2max test, which involved wearing sensors while exercising in a lab, but now anyone can get an estimate by wearing a smartwatch and moving around.
Is it good to have access to this kind of information? And how accurate could a wearable device be?
One day in November, my Apple Watch sent a high heart rate notification. That led me to look at my VO2max, which the Apple Watch said was 32, well below average for a man in his late 40s.
Looking for a solution, I joined a high-intensity interval gym, which specializes in cardio. Five months later, I felt progress. I burned fat, gained muscle, and felt more energetic. The Apple Watch gave me a VO2max estimate of 40, just below average, and a Garmin watch rated me at 45.
All that was left to do was perform an actual VO2max test. A few hours after pedaling on a stationary bike with an oxygen mask strapped to my face, I received my lab results: 25, a poor rating. Devastating.
Ethan Weiss, a cardiologist in San Francisco who has studied wearable technology, said my experiment highlighted the pros and cons of smartwatch data.
“For one thing, you can give it credit for prompting you to exercise,” he said. “But on the other hand, now you’re kind of freaking out with this actual test, thinking ‘What do I do with this number?’”
I took the lab test in March, when my gym in Oakland, California, called Sweat, announced that it had partnered with a metabolic health lab to offer clinical-grade VO2max testing. The test measures your maximal oxygen intake at the point of exhaustion.
Wearing an oxygen mask and heart monitor, I cycled on a stationary bike for about 12 minutes, increasing the intensity every minute. After I reached my maximum heart rate of 182 beats per minute and began to battle exhaustion, the test concluded.
The test was very different from the way wearable devices estimated my VO2max. Apple Watch and Garmin study your heart rate and movements as you walk or run for at least 10 minutes and record a score.
For their algorithms for how to make these estimates, Apple and Garmin conducted studies of people who were doing an actual VO2max test, as well as other exercises, and looked at their heart rates and various metrics.
The key word is “estimates”. The watches don’t actually measure your oxygen intake and therefore don’t actually measure your VO2max. One simple reason my wearable estimates differed so much from my actual VO2max result is that the way my body works doesn’t match the heart rate and oxygen intake patterns of Apple and Garmin study participants. That’s the danger of relying too much on algorithms.
I had no choice but to accept the hard truth: my VO2max result in the laboratory test was very low. But the report also showed many positives, including very high metabolic rate and fat-burning efficiency, and healthy breathing patterns.
With all this information, Cassie Hecker, the gym owner, rated my fitness level as “average,” higher than the Apple Watch’s cardio fitness rating of “below average.” She instructed me to focus on cardio training. Not in pessimism.
All the health experts I interviewed agreed that while portable data (much of it flawed) had caused me anxiety, it had achieved a net positive result. Apple Watch encouraged me to pay more attention to my health, and I am now healthier as a result. I look and feel better, and that’s all that matters.
BRIAN X CHEN
THE NEW YORK TIMES
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6679148, IMPORTING DATE: 2023-04-25 18:50:07
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