By Brandon Pigg
Published: October 7, 2026
Most sports coaches operate under the firm assumption that an athlete’s calves receive more than enough stimulus through sprinting, jump landings, and heavy plyometric drills. When additional calf work is actually factored into a training program, it almost always takes the form of some variation of the standing calf raise. While all of these movements serve a vital purpose in athletic development, they share a glaring blind spot: none of them effectively train the soleus muscle.
Understanding the anatomy and neural control of the lower leg reveals why traditional training methods leave this critical muscle behind. Although the gastrocnemius and the soleus both act as synergists sharing plantarflexion responsibilities, they are structurally and functionally distinct. The gastrocnemius crosses both the knee and ankle joints, whereas the soleus crosses only the ankle joint. This anatomical difference creates a complex and fascinating mechanical relationship between the two primary muscles of the calf.
Beyond this basic structural variance, neural impulses directed toward the gastrocnemius decrease as the knee joint moves into deeper angles of flexion, a phenomenon documented by Cresswell and colleagues in 1995. Conversely, the neural innervation of the soleus remains remarkably constant regardless of the knee joint angle. Research conducted by Lauber and coworkers in 2014 demonstrated that between zero and sixty degrees of knee flexion, the fascicle lengths of the soleus remain relatively unchanged. In stark contrast, the gastrocnemius fascicles progressively shorten by roughly three and a half millimeters up to approximately twenty-one degrees before stabilizing as flexion continues. Furthermore, researchers observed that gastrocnemius motor units began deactivating at a knee angle of roughly twenty-one degrees during passive flexion.
These findings are strongly supported by a 2014 study from Baumbach and colleagues, which found that knee flexion up to twenty degrees eliminates any inhibitory effect the gastrocnemius has on ankle dorsiflexion. Interestingly, the very same motor units deactivated during passive flexion at twenty-one degrees were reactivated at roughly thirty-five degrees of knee flexion during passive extension. The authors noted that activation levels between the gastrocnemius and the soleus actively alternate depending on joint angles and the corresponding fascicle lengths of the gastrocnemius. This means that when the knee joint angle places the gastrocnemius fascicles at an optimal length for force production, the gastrocnemius acts as the primary activated calf muscle, and vice versa when those fascicles shorten.
These insights suggest that the heavy burden of eccentric plantarflexion shifts decisively onto the soleus at knee angles exceeding twenty degrees. The soleus also functions as the dominant plantarflexor of the two muscles until the knee returns to roughly thirty-five degrees of extension. This validates the traditional view of the soleus as an eccentric muscle, given that it remains active through a broader percentage of knee flexion than extension.
Consequently, standard pogo jumps, drop jumps, and traditional calf raises do little to nothing to properly condition the soleus. While these movements are undoubtedly fantastic for strengthening the Achilles tendon and the gastrocnemius, the knee angles involved simply are not deep enough to shift the primary mechanical load away from the gastrocnemius and onto the soleus.
The critical question for high-performance coaches then becomes whether this distinction actually matters for overall athletic development. If the primary goal is reducing the risk of knee injuries among athletes, the answer is an emphatic yes.
Biomechanics research led by Elias in 2003 and Mokhtarzadeh in 2013 uncovered a vital functional dichotomy: the gastrocnemius acts as an antagonist to the anterior cruciate ligament, whereas the soleus acts as an agonist. Elias specifically demonstrated that when the soleus contracts in isolation, the tibia shifts posteriorly relative to the knee joint. Conversely, when the gastrocnemius contracts alone or alongside the soleus, the tibia translates anteriorly. Excessive anterior translation of the tibia relative to the femur places immense stress on the knee joint structures.
Because strengthening the soleus theoretically minimizes anterior tibial translation during jump landings, targeted soleus training may help mitigate the risk of patellar tendinopathy. The two primary mechanisms behind this hypothesis are straightforward: first, enhancing the load-bearing capacity of an additional muscle group during landing relieves excessive stress on the quadriceps and patellar tendons; second, reduced anterior tibial translation results in less stretching strain on the patellar tendon itself.
Integrating effective soleus training into an existing athletic regimen requires looking beyond standard equipment limitations. Because many training facilities lack dedicated seated calf raise machines due to budget constraints or spatial footprints, coaches must get creative. Traditional seated calf raises remain the gold standard for isolating the soleus, much like standing calf raises serve the gastrocnemius. However, several viable alternatives utilize common weightroom implements to achieve the exact same mechanical stimulus.
Using a safety squat bar offers one of the most effective substitutes for a traditional seated machine. Coaches can experiment with bar placement on the thighs, though positioning the load closer to the knee joint and nearer to the ankle articulation is generally preferred. Wrapping the bar with a protective pad or a thick towel ensures comfort during heavy loads. Alternatively, coaches can improvise using kettlebells suspended via lifting straps or dipping belts draped across the middle of the thigh, replicating the exact mechanical setup of a loaded seated raise.
Isometric training offers another powerful avenue for soleus development, particularly for athletes managing Achilles tendon sensitivities who struggle with dynamic end-range ankle movements. Executing a ninety-nine-degree isometric hold allows athletes to work the soleus in a position of maximal contraction while entirely excluding the gastrocnemius due to the deep knee bend. Similarly, performing seated calf raises against immovable safety pins in a power rack enables targeted isometric overspeed training at the point of maximum soleus extension.
Dynamic multi-joint movements can also be manipulated to emphasize the soleus. Prowler sled jumps require athletes to deliberately delay knee extension, ensuring foot contact occurs with a deeply flexed knee before explosive propulsion. Ten-yard uphill sprints provide a similar mechanical advantage, as the incline naturally forces adequate knee flexion to engage the soleus even without maximal sprint mechanics. Furthermore, incorporating squatting drop jumps rather than stiff-legged drop landings eliminates the initial gastrocnemius damping effect, forcing the soleus to act as the primary eccentric plantarflexor from the moment of ground contact.
Ultimately, while soleus conditioning may not represent a singular hidden secret standing between an athlete and a world record, it remains a valuable piece of the puzzle when building a comprehensive, resilient athlete. Incorporating targeted lower-leg variations beyond traditional plyometrics ensures that every muscle group crossing the ankle joint is properly prepared for the immense forces encountered in elite sport.
