Single leg calf raise on step, knee flexed ("Heel raises" Soleus strengthening, on step, single leg, near wall)

Step up on to a step with a supportive surface such as a wall in front of you.
Walk your feet back so that your heels are off the edge of the step.
Lift your unaffected leg.
Bend your knee on your stance leg, then perform a calf raise, rising up onto your toes.
Control the movement as you lower your heel back down.
Ensure your knee remains bent throughout.