Plank steady, kick the band back.
Keep your hips from rotating when the leg lifts, the plank stays dead level.
The moment one foot leaves the floor in a plank, your core has to stop the pelvis rotating toward the unsupported side, and kicking that leg up against an ankle band multiplies the force it must resist. Held for time and worked one leg at a time, the plank becomes an active anti-rotation drill rather than a static hold. The kicking leg gets its work, but the dead-level trunk is the actual product.
Squeeze the grounded glute hard and shorten the kick. The lift only counts if your beltline stays parallel to the floor, height is irrelevant.
Just past hip height at most. Kicking higher forces your lower back to arch and turns core work into spine extension.
Halve the interval, one leg per half, or alternate legs each rep through the full time. Either works, just keep the split even so one side does not get an easy ride.
