Tie a theraband (wide) around a fixed object like a pole, table or sofa leg. Then put the band around one heel, on a diagonal across the heel. Step away from the pole as much as you need to get load onto the heel but not so much that you struggle in the raise or it pulls your foot out of line. Go through a normal eccentric calf raise.

Position the band depending on if you need a lateral load or a medial load - see the education video below for all the details