3 ways to estimate VO2 max: https://www.wikihow.com/Measure-VO2-Max
https://www.rei.com/learn/expert-advice/how-to-measure-and-improve-your-vo2-max.html
https://www.worldfitnesslevel.org/#/
fast 1.5 mile test https://marathonhandbook.com/diy-vo2-max/