If you look at the anatomy of the calf, you’ll easily notice there are two muscles. The outermost muscle is called the gastrocnemius. And, the deeper muscle is called the soleus. Both of these fuse into the achilles tendon and attach at the heel. But, they function in a slightly different way…

Yes, these muscles comprise the calf complex but there is an anatomical difference that we need to consider. It’s that the gastrocnemius muscle crosses the knee joint, while the soleus muscle does not. Anatomy and location dictate function and this means they need to be targeted in different ways when looking to improve flexibility and/or build strength.

When considering the joint actions that these muscles create, the gastrocnemius plantarflexes the ankle AND flexes the knee, while the soleus muscle primarily plantarflexes the ankle since it only crosses one joint. Therefore, the gastrocnemius is more dominant during knee extended, plantarflexion. And, the soleus is more dominant during knee flexed, plantarflexion.

Now that we understand the difference between these muscles from an anatomical standpoint, we must also discuss why this matters for runners. While running, the knee never completely extends. Values range on the normal amount of knee motion since it depends on the individual runner. But, we typically see approximately 15-degrees of knee flexion throughout midstance. Because the knee never extends and remains in some degree of flexion during initial contact, midstance, and toe off, the soleus becomes the more prominent player in the calf complex.

By no means are traditional calf raises wrong! We must also address the calf/ankle with exercises where the knee is flexed. Ultimately, this will provide the most carryover to running.Below, let me share with you a simple soleus strengthening progression to build bulletproof calves and improve running performance…

Soleus Wall Sit

The soleus wall sit is an exercise I picked up from Chris Johnson in 2018 at one his running seminars. I immediately liked this exercise because it allowed easy loading of the soleus in a wall sit position. There’s no better way to kill two birds with one stone. Plus, the depth you sit in the wall sit will dictate the amount of load so it is easily modified depending on the person. When completing this exercise, perform for 3 sets of 30-60sec and add additional resistance as needed.

Tip Toe Walking

Tip toe walking is another exercise taught at the same seminar. Similar to the soleus wall sit, this is an isometric exercise where we are targeting strength/endurance without creating any motion at the ankle joint. But, the walking nature allows a greater degree of challenge while absorbing force on each foot strike. When completing this exercise, perform 3 sets of 10-15 feet and add additional resistance as needed.

Bent Knee Calf Raise

The next exercise to target the soleus is the bent knee calf raise. This is very similar to traditional calf raises but while maintaining a degree of knee flexion. Now that we are moving through the range of motion, it’s important to reinforce a full range of ankle plantarflexion. When completing this exercise, perform 3 sets of 10 repetitions and add additional resistance as needed.

Bent Knee Calf Raise on the Leg Press

The final exercise in this series is designed for a greater degree of loading. You can certainly load more with dumbbells or barbells, but I often like to take balance and stability out of the equation to focus on one variable. When completing this exercise, perform 3 sets of 10 repetitions and add additional resistance as needed.

I hope you enjoyed these soleus strengthening recommendations. They have been very impactful for my clients to increase calf strength, improve running performance, and reduce the likelihood of plantar fasciitis, achilles tendinopathy, and other common lower leg injuries.

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