So something has sparked your interest in the soleus. If I’m taking a guess, a physical therapist has probably encouraged you to strengthen your soleus, or a massage therapist has found it’s a “problem area” for you while performing soft tissue work. Maybe you’ve been experiencing some pain in your calf with running, but all the usual gastroc stretches just don’t work. It’s even possible that you’ve recently dove into some self-study and research, and you’ve been surprised to find another muscle that sits beneath your gastroc! Rightfully so: The soleus is generally an under-appreciated muscle that gets so little attention. Regardless of your reasoning, you’ve come to the right place. We’re going to spend our efforts here in this article diving into the soleus: what is it, what isn’t it, what does it do, and what are the best soleus exercises? And most importantly, does it even matter? Read on to find out.

 

The Soleus: What is it?

The soleus is a flat and broad muscle that sits just underneath its more popular counterpart, the gastrocnemius. In technical terms, it originates from the soleal line/medial border of the tibia, head of the fibula, and the posterior border of the fibula. In practical terms, it originates from the two bones that make up your shin, starting right below the knee joint line.

A great picture of the soleus created by BodyParts3D, © The Database Center for Life Science.

If you take the time to appreciate the image above, there are two major things worth taking note of. First, the gastrocnemius, which usually sits on top of the soleus, has been removed. If it were still included, you wouldn’t be able to see the soleus deep to it. Second, notice how the soleus stops right below the knee joint line. Unlike the gastrocnemius, the soleus only crosses the ankle and is largely comprised of type 1 slow twitch muscle fibers (1), meaning that the soleus is fairly resistant to fatigue.

Although the soleus does have its own separate and anatomically distinct origin, it actually blends into the Achilles tendon with the gastrocnemius. Another close-by neighbor is the plantaris, a pretty weak and generally useless ankle flexor. Due to the unique anatomy of these three muscles, the calf is often referred to as the triceps surae in the medical/rehabilitative literature. The action of the soleus is to create plantar flexion (pointing the foot down). It serves a particularly important role in standing, walking, and running. If not for its fatigue-resistant pull, it would be far more challenging to maintain a clean, up-right standing posture.

 

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The Soleus: What isn’t it?

Well, in short, the soleus isn’t a lot of things. Clinically, it typically isn’t an extremely pertinent muscle. Don’t get me wrong, it has a role, and shouldn’t be neglected, especially in the management of Achilles tendinopathy. But it doesn’t carry the same weight or influence that the gastrocnemius holds in the medical world. The gastrocnemius is considered at a much higher risk of strains because it crosses two joints (the knee and the ankle) and has a high density of type two fast twitch muscle fibers (1). The resulting combination of unique anatomy, and the muscle fiber type, doesn’t always equate for the best recipe safety wise. However, it certainly has a higher ceiling for athleticism and force production than the soleus.

A great picture of the gastrocnemius created by BodyParts3D, © The Database Center for Life Science.

Compare and contrast the picture of the gastroc above to the previous picture of the soleus. Again, the biggest delineation between these two muscles is their origins. Appreciate the gastroc begins above the joint line, whereas the soleus begins below the joint line.

Lastly, if the soleus is the step-child that never got the recognition it deserved next to the gastroc, the plantaris (the third muscle of the triceps surae) is the distant cousin that the family shunned to live in the backyard shed. Poor plantaris. Of note, the plantaris is a very weak ankle plantar flexor, and is considered to be largely vestigial. In other words, it becomes functionless over the course of human evolution. In comparison to the plantaris, the soleus certainly holds more function. However, if looking for some physical therapy trivia, the plantaris is said to be the longest tendon in the body. (If you ever get this as a question at your local pub trivia night… you’re welcome.) Funny enough, due to its strange anatomy, it’s often mistaken as a nerve in cadaver lab among medical, physical therapy, physician assistant, and chiropractic students.

A graphic of the plantaris, again created by BodyParts3D, © The Database Center for Life Science.

So in short, the soleus has some clinical value (which we’ll dive into here soon), but it truly isn’t an astronomical amount. It’s far from an evolutionary remnant, or worthy of being the subject of an obscure trivia question. In other words, keep it on your radar, but in most cases trust your musculoskeletal healthcare provider when they turn most of their attention to your gastroc first.

And If a clinician ever tells you that you have a plantaris strain without legitimate imaging, please tell them they’re a dork. You can tell them I said so.

 

The Muscles Every Runner Should Be Strengthening

 

The Soleus: What does it do?

We’ve hinted at the function of the soleus several times already, but its main action is to provide plantarflexion (pointing the toes down) with the knee in flexion (bent). The further the knee is placed into flexion, the more the soleus becomes the primary generator of force in plantarflexion (1). The straighter the knee is, the greater the contribution of the gastrocnemius. It’s a fun party trick for the musculoskeletal healthcare provider — it allows us to gather some information by strength testing your calf muscle in various ranges of motion. It provides nice insight to determine where we want to place our efforts from a rehabilitative perspective.

In addition to its muscular action (plantarflexion), it also serves as an important “muscular pump.” Meaning that in conjunction with the gastroc, when it’s contracted, it helps to heavily influence the venous return of blood upwards towards your heart. Since veins are more passive than arteries, they rely heavily on surrounding musculature to contract and help encourage venous flow. So yes, all those silly ankle pumps you were instructed to do after your knee surgery is/were important after all.

READ: HOW TO STAY ACTIVE AFTER SURGERY

 

So What Are The Best Soleus Exercises?

To be totally honest, the exercise prescription for the soleus isn’t all that sexy. As we’ve mentioned already, to work the soleus, perform calf raises with your knee bent to 90 degrees. That’s it. Now, as physical therapists, we like to have different programming for different situations. And if nothing else, it’s important to be able to perform a “lateral” with your programming: if a particular exercise is becoming boring/redundant, or if it’s painful, perform a lateral to a different exercise that provides the same purpose with a slightly different movement. The examples I’m going to provide below are a few of my favorites. Appreciate that the list I’m going to give you is far from exhaustive — but these are a great place to start and will help provide some variety other than the seated calf raise machine at your local gym.

Seated Soleus Raises

The most traditional and straight-forward soleus exercise. These can be performed with a dumbbell (as I demonstrate in this video) or on a fixed, seated, soleus raise machine that’s pretty common to find in a gym setting. The soleus raise machine doesn’t offer much utility outside of strengthening your soleus, so you’re not likely to find this in your physical therapy clinic or specialized gym (CrossFit, etc.)

 

Soleus Bridges

An interesting spin to add to a bridge. I’m all about exercises that combine movement patterns (when appropriate and provide actual yield), and this one has always been a favorite. Essentially, you’ll perform a traditional supine bridge with a heel raise at the top. Or, you can hold it isometrically throughout the full movement. You’ll probably need a half-moon foam roller or something else to prop your toes onto.

 

Squat with Soleus Raise

The soleus can be worked even at the end-range of a squat. Naturally, this will likely have to be a hip dominant squat, where your tibia remains vertical. You’ll probably have to hold onto the upright of a squat rack or have a partner support you by holding onto a thick mobilization band. Regardless, it’s just another option in your soleus strengthening efforts.

 

Lunges with Soleus Raise / Sneaky Lunges

A similar idea to adding the soleus raise onto the end of a squat can also be added to a lunge. “Sneaky” lunges are another fun variation for triceps surae and foot intrinsic strengthening. I’ll use this often in clinic.

 

Soleus Stretch

Stretching the soleus is as simple as strengthening it: just bend your knee, then perform a traditional gastroc stretch. I can’t think of many times I’ve had to specifically had to stretch the soleus in the clinic, but it could certainly affect your ability to dorsiflex (pull your foot/ankle up towards you) the foot if “tight.” More practically, many who have tight calves will appreciate performing this in a static stretch routine.

 

Manual Soleus Soft Tissue Release

While “release” is an inaccurate term, this manual technique might help relieve some discomfort if you feel like your soleus needs some soft tissue work. This can help to blunt pain levels, reduce muscle tone and help the calf feel a bit looser.

 

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Does it even matter?

So does paying attention to the soleus as part of your exercise or rehabilitative programming even matter? Probably. The lower-limb muscles largely responsible for pushing on the ground forcefully during running are the major ankle plantar flexors (gastrocnemius and soleus). Both have been shown, in combination, to be largely responsible for a large portion of the ground reaction force in the vertical direction and nearly all of the propulsive components of the ground reaction force in the anterior/posterior direction while running (2). In other words, these muscles do contribute to running performance. Now, it’s realistic to figure the gastroc has a higher ceiling in terms of improving explosiveness/strength due to the influences that come from primarily type II muscle fibers (known for their quick twitch properties and force production). Does that mean the soleus should be neglected? Nope. Does it mean the soleus should get 30 minutes worth of dedicated programming in an hour-long strength and conditioning session? Nope. As always, need to make sure the juice is worth the squeeze. The gastroc will likely always get more attention, and rightfully so.

LISTEN: CHOOSING THE CORRECT RUNNING SHOES WITH DR. JASON TUORI

 

From a rehabilitative/sports medicine perspective, it is possible to strain the soleus. However, it certainly isn’t as commonly seen in the gastroc. The presentation of a soleus strain tends to be far less dramatic than that seen in the gastroc (1). The classic presentation is calf tightness, stiffness, and pain (1). For a true diagnosis of a soleus strain, strength testing of the calf should be performed with both the knee straight and bent. There should be a good palpatory exam using principles discussed in the soleus soft tissue video listed above. And finally, it will likely require some formal imaging to confirm. It’s pretty common for soleus strains to get lumped together with gastroc strains. And to be completely honest, the rehab will look almost nearly identical.

So in summary, the soleus does matter. To the extent of which it matters is probably debated. If any of what we’ve discussed here seems like it applies to the pain you’re dealing with, you may be onto something. However, please don’t miss the forest because you’re staring at one tree.

 

Closing Thoughts

• The soleus is a fairly under-appreciated muscle next to its larger neighbor, the gastrocnemius. It holds some value from a clinical and performance perspective, but focusing on the gastroc likely will provide more yield.

 

• Soleus strains are fairly rare, gastroc strains are very common.

 

• The gastroc has a higher ceiling for developing explosiveness, and power and providing more contributions to overall athleticism.

 

• The plantaris serves little if any value.

 

• The soleus provides plantarflexion (pointing the toes down) primarily with the knee bent to 90 degrees of flexion. This positioning holds true if you’re trying to exercise the soleus.

 

• The exercise programming for the soleus isn’t sexy or creative, but there are many different ideas to thread into your exercise programming. Your biggest challenge with exercising the soleus will be trying to avoid boredom as the concepts are fairly linear.

 

Take Control of Your Achilles and Calf Health!

The name Achilles originates from ancient greek mythology. A hero was dipped into the river Styx by his mother. She was holding onto him by the heels when she dipped him and the thought is that because this spot was covered it was considered vulnerable. Later on in life, during battle, Achilles would suffer death from an arrow hitting the strongest tendon in the body. All of this to say the solution to an invulnerable or robust achilles tendon is not by dipping it in water, it’s by creating strength and elasticity! Keep your feet dry and calf strong with this program.

 

References

1. Dixon JB. Gastrocnemius vs. soleus strain: How to differentiate and deal with calf muscle injuries.  Cur Rev Musculoskelet Med. 2009; 2: 74-77.

2. Schache AG, Dorn TW, Williams GP, Brown NA, Pandy MG. JOSPT. Lower-limb muscular strategies for increasing running speed. 2014; 44(10): 813-824.

 

About The Author

Christopher Lefever, PT, DPT, SCS, CSCS, USAW

[P]Rehab Writer & Content Creator

Originally from Reading, Pennsylvania, Chris graduated with his bachelor’s degree in exercise science and a doctorate of physical therapy from Slippery Rock University. He afterwards completed a sports physical therapy residency at the Memorial Hermann IRONMAN Sports Medicine Institute. He later completed a division 1 sports physical therapy fellowship at Duke University where he worked closely with Duke football, basketball and lacrosse. He returned to Houston afterwards with Memorial Hermann to help develop an emerging division 1 sports physical therapy fellowship. Present day, he practices with the sports medicine team at the United States Olympic and Paralympic Committee in Colorado Springs, CO. Chris is a board certified sports clinical specialist (SCS), certified strength and conditioning specialist (CSCS) and certified in dry needling. He has a particular interest in post-operative rehabilitation of the athletic knee, shoulder, hip and elbow.

 

 

 

 

 

Disclaimer – The content here is designed for information & education purposes only and is not intended for medical advice.