Tried this 2 years ago:

https://www.fitnessblender.com/videos/brutal-hiit-ladder-workout

Approached this again this morning with fear and trepidation despite being reasonably fit. Am happy to report Workout Complete but by golly gosh, my lungs were telling me in no uncertain terms they were sick and tired of being abused and were trying to leave through my throat😂!

Think Imma do this more frequently as a marker to gauge my relationship with me lungs!