If you haven't read anything about it, check out the DC method. Slow reps up, squeeze and hold, slow reps down, hold stretch at bottom. DC dictates 15 second stretch before next rep. Might have to lower wome weight, but focus on squeeze and stretch. And the reason the donkey calf raises are so nasty, is that by bending over at the waist, you are "prestretching" the calves, even when you are flat footed. By stretching them down at bottom of rep, it stretches harder.