The Seated Calf Raise works your calf muscles, particularly the Soleus muscle which extends from just below the knee and all the way into the heel. In comparison to Standing Calf Raises this exercise works your Soleus more and your Gastrocnemius less. A strong Soleus muscle is essential to provide power into your step when running.
To perform a seated calf raise begin by sitting at the edge of a box or chair with your legs bent at a right angle. Place a kettlebell or dumbbell on your working leg just above the knee. Raise the heel of your working leg upwards until that foot is effectively on tip-toes. Squeeze and pause at the top of the movement before lowering back down.
You can use a relatively large weight for this exercise.