When you hear most people refer to the calf muscles, they are referring to the two side-by-side muscles that protrude from the back of the lower leg – especially when the heels lifts off the ground. These side-by-side muscles are heads of the gastrocnemius muscle.
Perhaps the reason why the soleus muscle is not considered a calf muscle (or any muscle for that matter) is because most people, even runners, don’t know it exists. This is likely because it is hidden underneath the gastrocnemius and thus, out of sight, out of mind.
Did you fall on your face?
You’ve just learned perhaps the most important role of the soleus. The soleus constantly ‘pulls’ to keep you from falling forward and keeps you balanced while standing or when walking/running.
The soleus also works with the gastrocnemius to plantar flex (point foot downward) the foot – especially while walking.
Despite the soleus not getting the attention it deserves, in respect to running, it carries a lot more of the load than the better known gastrocnemius. This is why between the soleus and the gastrocnemius, the soleus muscle is usually the one that gets the most sore when running, especially by those that run with a midfoot strike and even more so by those that are in the process of converting to a midfoot strike.
As noted above, the soleus is almost always working – at least when standing or walking/running around. Due to this, it has excellent endurance and fatigue resistant properties. As such, it is made up of predominately slow twitch fibers as compared to the gastrocnemius, which is primarily made up of fast twitch fibers.
How To Tell If The Soleus Is Tight
Due to the different muscle attachment points, here’s a good way to tell if your muscle soreness is from the soleus.
Stand facing a bench, bend your knee, put the ball of your foot on the bench and drop the heel. If you feel muscle tightness in your calf muscle region, it’s likely the soleus.
Conversely, stand facing a wall and put straighten out one leg behind you, making sure the heel is on the ground. Does it hurt? If so, it’s likely your gastrocnemius that is sore.
As one of the functions of the soleus is to plantar flex the ankle, runners who overstress the soleus will notice that plantar flexion of the ankle becomes painful along with restricted movement.
As such, from a running perspective, there are two primary ways to strengthen the soleus. First is to run more but making sure volume increases are incremental. This is especially the case if running with a midfoot strike. Second, is to perform a specific exercise to target the soleus. Assuming you don’t have access to a gym with a seated calf raise machine, this is most effectively done by bending the knee at a decent angle and using a theraband or like products to provide resistance while plantar flexing the ankle. This is most easily facilitated in a seated or supine position, as depicted in the above video.
While hidden and thus often overlooked by the more impressive looking gastrocnemius, don’t forget about the soleus because if it weren’t for it, you’d likely be face planting every time you take a step.
Rick Prince is the founder/director of United Endurance Sports Coaching Academy (UESCA), a science-based endurance sports education company. UESCA educates and certifies running and triathlon coaches (cycling and ultrarunning coming soon!) worldwide on a 100% online platform.
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