Isometric Strength of the the Soleus and Gastrocnemius

KangaTech have two protocols within our testing and training repertoire that have been designed to assist with the differential assessment and training of isometric strength of both components of the Tricep Surae (calf) muscle - the Soleus and Gastrocnemius.

These protocols utilize variations in knee flexion angle during a combination of closed chain maximum isometric ankle plantarflexion protocols performed in standing and sitting to assess and train the Gastrocnemius and Soleus muscles (Bojsen-Møller et al, 2006).

Why is this differentiation important? Calf muscle injuries are common in elite sport with the majority of calf injuries affecting the most powerful ankle plantar flexors, the soleus and the gastrocnemius. Soleus muscle injury incidence has been linked with locomotor based sports and is thought to commonly occur during steady state running. In contrast, Gastrocnemius injuries have been observed during explosive actions such as acceleration and jumping (Green, 2020. Meek et al, 2022). Both muscle injury types result in a high mean return to sport time (Dixon, 2009). In addition to this, from a movement efficiency perspective, the Soleus also plays a role in controlling knee joint forces associated with injury risk in other regions - e.g. ACL injury risk (Maniar et al 2018).

There is also a need to understand the relative contribution these muscles may make to the function and health of the Achilles Tendon. The soleus muscle has the largest physiological cross-sectional area of any lower limb muscle, enabling the production of 8 times body weight force (Ward et al, 2009, O’Neill, 2019). It’s central aponeurotic tendon extends distally contributing to the formation of the Achilles tendon (Balius et al, 2012). The deeper surface of the mid portion of the Achilles is comprised of fascicles linked to the soleus and undergoes the largest displacement during ankle movement. Tendinopathies are commonly seen in this region of the Achilles tendon (Slane & Thelen, 2015). Reduced peak force/strength endurance of the Soleus is associated with Achilles Tendinopathy (O’Neill, 2019).

In summary, weakness in ankle plantar flexion is generally considered a risk factor for Achilles tendinopathy and calf muscle injury. The differential use of isometric plantar flexion training in straight and bent knee positions can be used as an effective profiling and training tool, in conjunction with dynamic movement, to understand where risk may exist and to improve function of this muscle group to mitigate injury risk and augment athletic performance. 

KangaTech customers can find the Mid-Thigh Pull suite of protocols on KT Software and on the User Guide.

To find out more about how these protocols can be implemented get in touch. 

Calf muscle strain injuries in elite Australian Football players: a descriptive epidemiological evaluation
Green B, Lin M, Schache AG, McClelland J, Semciw A, Rotstein A, Cook J, Pizzari T,
Scand J Med Sci Sports. 2020; 30: 174– 184.

Calf Strain in Athletes
Meek W, Kucharik M, Eberlin C, Naessig S, Rudisill S, Martin S.
JBJS Reviews: March 2022 - Volume 10 - Issue 3 - e21.00183

Plantar flexor strength and endurance deficits associated with mid-portion Achilles tendinopathy: The role of soleus.
Seth O'Neill, Simon Barry, Paul Watson,
Physical Therapy in Sport,
Volume 37, 2019.

Low-intensity tensile loading increases intratendinous glucose uptake in the Achilles tendon
J. Bojsen-Møller, K. K. Kalliokoski, M. Seppänen, M. Kjaer, and S. P. Magnusson
Journal of Applied Physiology 2006 101:1, 196-201

Maniar N, Schache A, Sritharan P, Opar D.
Non-knee-spanning muscles contribute to tibiofemoral shear as well as valgus and rotational joint reaction moments during unanticipated sidestep cutting.
Sci Rep 2018 Vol. 8 Issue 1 P:2501

Talking Tendinopathies & Solving the Soleus Conundrum with Seth O’Neil. Episode #375