Peter Attia uses cycling for Zone 2 training, and previously used a treadmill with a 15-degree incline and a brisk walking pace when traveling.

“do i always bike for zone two these days yes i bike exclusively for zone two back when i traveled a lot if i was at a hotel or at a place where the bike sucked i would treadmill and i had a hole i knew exactly what i needed to do on a treadmill it was whatever this deepest incline is on treadmills i think it's about 15 degrees and it was i forget how many miles per hour but it was you know less than four miles per hour it was a very brisk walk at 15 degrees”

“zone two cycling and my zone two is you know somewhere between 220 and 235 watts so i kind of took a slightly lower estimate i just said just let's average 225 watts and you can you can use a calculator to tell you how many mets that is so that's 11 mets and if i spend four hours a week there 11 times 4 44. so that's 44 met hours per week”