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  • Writer's pictureMandy Willis

Calf Strains and Calf Capacity... is there a link?

The calf complex is a critical group of muscles for both athletic performance but also for function in daily living. The calf allows us to stand, walk and participate in activity. The calf is largely involved in athletic demands that require both explosive and endurance-based function, high-speed or high-volume running loads, acceleration and deceleration demands, and activities that require prolonged performance under fatiguing conditions (Green & Pizzari, 2017).

Calf strains are a common soft tissue injury that, if not managed well, can have high risk of re-injury and prolonged recovery. Calf strains represent one of the higher soft tissue injury incidences within AFL, reporting 3% per club per season, and up to 16% rate of recurrence (Green & Pizzari, 2017).

The most common demographic that are affected by calf strains are males over 35 years of age, with 70% of calf strains occurring in male populations (Taunton, 2002). Increased athlete age and previous strains are strong risk factors for future recurrence – which is consistent with other muscle strain populations, including hamstring, groin and quadricep strains (Green & Pizzari, 2017).

Read on to learn more about the types of calf strains and how to assess your own calf function.

Background Anatomy and Function:

There are 3 main muscles within the calf complex, these include:

1. Gastrocnemius –

· This muscle has a medial (inner) head and a lateral (outer) head. The gastrocnemius is bi-arthrodial, which means it crosses and functions at two joints: the knee and ankle.

· The gastrocnemius contributes to the initiation of knee flexion (bending of the knee) in the first 15-20 degrees but is largely known for its function in plantarflexion (pointing of toes).

· The gastrocnemius is primarily made up of fast-twitch muscle fibres and is therefore the powerhouse for force production within the calf complex and is responsible for generation of force for jumping and sprinting.

· The medial head of the gastrocnemius is most prevalent in calf strains equating to 58-65% of calf strains (Counsel, 2015)

2. Soleus –

· Sits below the gastrocnemius and is our endurance-based calf muscle.

· The soleus only crosses the ankle joint and therefore has no input into knee flexion movements.

· The primary role of the soleus is to stabilise our tibia (lower leg bone) on the calcaneus (heel bone) limiting forward sway when standing, and generating endurance-based plantarflexion movements such as walking, longer distance or slower speed running.

· It is largely comprised of slow-twitch muscle fibres, making it the large contributor to endurance activities like running

The soleus contributes to 58-66% of calf strains (Counsel, 2015)

3. Plantaris –

· This muscle is not a major functional contributor, however works with the gastrocnemius to assist initial flexion at the knee and plantarflexion at the ankle.

Interestingly this muscle will be absent in up to 20% of lower limbs.

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All three of these calf muscles insert into a common tendon, widely known as the Achilles Tendon.

Types of strain:

Gastrocnemius strains are common and higher risk as the muscle crosses two joints. It is commonly injured during explosive movements such as sprinting and jumping, when the knee is extended and the ankle is dorsiflexed, placing the muscle under tension in its lengthened position. This type of strain is the typical sudden, sharp onset of pain that is often described with muscle strains.

Soleus strains are more common in endurance-based runners, middle aged demographics and poorly conditioned athletes. This type of strain can feel more like a gradual onset, rather than an acute episode, worsening with running/activity.

Calf involvement in force production:

Did you know that 50% of running force propulsion comes from plantar flexor musculature? A common misconception is that our hip muscles are the primary driver for running – whilst important, they actually only contribute to 5-10% of force production in running. In terms of peak muscle force, the soleus generates 6.5-8 x body weight, whilst the gastrocnemius generates peak forces of up to 3.5-4.0 x body weight. Calves are often neglected or an overthought in training regimes, but they play a big role in healthy, efficient, and injury-free running.

Age-Related Changes:

Between the ages of 20 and 60 years, our plantarflexors are largely affected in the following ways:

- 15% reduction in cross sectional area, which is the size of our calf muscle

- 17.1% reduction in Achilles tendon stiffness (our ability to store and release energy to produce force)

- 31% less power during running

This is happening due to a process called sarcopenia, which is the medical term used to describe the musculoskeletal changes related to the aging process. It is even more important to incorporate calf conditioning into our active populations to slow down this process and preserve and restore as much healthy function of our calves as we can.

Self-Screening Tool:

If you’re a runner, a quick check of your own calf capacity can be simply screened by looking at how many good-quality single leg calf raises you can complete to fatigue. These need to be slow and controlled, full range of motion and with your pressure directed over your first and second toe (no rolling out towards little toe). The below table gives age based normative values that are satisfactory for running or active populations:

Table sourced from Herbert-Losier et al., 2017

Seek Advice:

It is estimated that 60% of running injuries are attributable to training errors (Hreljac, 2005). This can be reviewed and personalised to your current level and goals by seeking professional advice around structured and gradual loading programs to minimise your risk of training related errors and injuries.

If you do injure your calf, it is important to have it assessed clinically, as there are an array of other clinical presentations that can often present as a calf like strain which is important to have these ruled out and your type of calf strain be diagnosed. This will also ensure your rehab program is tailored to function specific demands of the muscle injured and the demands of the activities you wish to return to.

Proper rehab is integral in reducing risk of recurrence for calf-related injuries. Capacity to load and exposure to load are two integral parts to success in rehab that require understanding of pathology, tissue healing and functional property of the tissue.

Watch out for a follow up blog on how to build calf capacity and minimise the risk of injury.

Evolved Physio is a welcoming physio clinic located in Footscray/Maribyrnong in Melbourne's inner west. Our experience physios are experts in assessing and diagnosing musculo-skeletal injuries and our 45 minute treatment times allow us to fully assess, treat and rehabilitate your injuries. find out more at


Counsel P, Comin J, Davenport M, et al. Pattern of fascicular involvement in midportion Achilles tendinopathy at ultrasound. Sports Health. 2015; 7:424–8.

Green, B., & Pizzari, T. (2017). Calf muscle strain injuries in sport: a systematic review of risk factors for injury. British journal of sports medicine, 51(16), 1189-1194.

Hébert-Losier K, Wessman C, Alricsson M, Svantesson U. Updated reliability and normative values for the standing heel-rise test in healthy adults. Physiotherapy. 2017;103(4):446–452. doi:10.1016/

Hreljac A. Etiology, prevention, and early intervention of overuse injuries in runners: a biomechanical perspective. Phys Med Rehabil Clin N Am. 2005;16(3):651–vi. doi:10.1016/j.pmr.2005.02.002

Taunton JE, Ryan MB, Clement DB, et al (2002). A retrospective case-control analysis of 2002 running injuries. J. Sports Med. 36:95–101.

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