https://docs.google.com/spreadsheets/d/1WFbrawbpMzZugC97vHgGenPxuA8UMgrlP9a5HA5YJJ8/edit#gid=2139575813
old routine sheet
https://docs.google.com/spreadsheets/d/1GpNBWlaPULcJosDeMa0uwuYZKsOcMjLqVDeXv6f45Xo/edit?usp=sharing
https://www.howardluksmd.com/lactate-lactate-shuttle-lactic-threshold-workouts-in-polarized-training/
https://www.bodybuilding.com/content/ultimate-8-week-hiit-for-fat-burning-program.html