Looking for CE credits that level up interval craft and endurance periodization — real work, not fluff. I coach a 6 a.m. Tuesday crew and program VO2 30/15s, over-unders, and zone 2 builds; if you’ve done Stages SCU, Schwinn PWT, or NASM HIIT, which delivered the strongest science and take-home drills for a 12-week base-to-peak block?