How to find your critical power
Critical power is not new, but exercise physiologists and medical professionals have largely ignored it because it’s not easy to measure.
“People generally train off VO2 max or maximum heart rate, which is even less precise,” Dr. Gifford says.
Finding people’s critical power in the study involved multiple timed trials and calculating the relationship between speed/power and time, Dr. Gifford explains.
But for a rough measure of your critical power, you could use an app that measures functional threshold power (FTP), something Dr. Gifford refers to as the “Walmart version” of critical power. “It’s not exactly the same, but it’s close,” he says. (The app Strava features FTP as well as a pretty sophisticated power analysis.)
Or skip the tech and go by feel. If you’re below your critical power, “it’s going to be challenging, but you’ll feel under control,” Dr. Gifford says. Above your critical power, “your breathing and heart rate will continuously climb until you fail in about 2 to 15 minutes, depending on how far above you are.” Still, you don’t need to know your critical power to start exercising, Ms. Collins notes.
“The beauty of exercise is that it is such a powerful drug that you can see benefits without fine-tuning the workout this way,” Dr. Gifford explains. “I would hate for this to become a barrier to exercising. The important thing is to do something.”
A version of this article first appeared on WebMD.com.