Middle level work is an idea by Martin Kivaldy. You need to stay where the burn is. Never go fully up, never fully down, but travel up and down within this range. I use Chinese martial arts as a guiding picture. The middle level is an inefficient space we often just travel through. Stay there. And within the middle level look where it is difficult. Explore that. Stop motion style means you regularly stop and stay in a position for a moment.
For a start use 60–120s with 0.5–1 rest ratio. Start with 3 sets.
For example: 3 x 90s work 60s rest.
Joseph Bartz 22.07.2021