Muscles of the calf complex
The lower leg is an important biomechanical element during movement, especially in sports that require power and endurance.  The calf complex is an important component during locomotor activity and weight bearing. Injuries to this area can affect a variety of sports and sports crowd.  Calf muscle strain (CMSI) typically occurs during sports that involve acceleration and deceleration from high-speed running or increased running loads, and under fatigued conditions during competition or performance. 
A calf strain is a common muscle injury that, if not treated properly, carries the risk of re-injury and prolonged recovery time. Muscle strains usually occur at the medial head of the gastrocnemius or near the tendon junction. The gastrocnemius is more prone to injury because it is Interarticular muscles that extend to the knee and ankle. Sudden acceleration can lead to injury as well as sudden eccentric overstretching of the muscles involved. 
Clinically Relevant Anatomy
The calf refers to the muscles at the back of the lower leg.
It is composed of three muscles:
- Gastrocnemius – Together with the soleus, primarily provides plantar flexion of the ankle and flexion of the knee.  Plantar flexion provides propulsion during gait. Although it spans two joints, the gastrocnemius cannot develop its maximum strength at both joints at the same time. If the knee is bent, the gastrocnemius cannot generate maximum force at the ankle, and vice versa. 
- Soleus – Located below the gastrocnemius muscle in the superficial posterior compartment of the calf. Its primary function is plantar flexion of the ankle and stabilization of the tibia over the calcaneus, limiting forward sway. 
- Plantaris – Located in the rear surface compartment of the lower leg. Functionally, the plantaris is not a major contributor, acting alongside the gastrocnemius as the knee flexor and plantar flexor of the ankle 
These muscles come together to form the Achilles tendon, and all three muscles insert into the heel bone.
Muscle strains most commonly occur in bijoint muscles such as the hamstrings, rectus femoris, and gastrocnemius. So when we refer to a calf strain, we’re usually referring to a gastrocnemius strain.
During physical activities such as sprinting, these long double-joint muscles must cope with high internal forces and rapid changes in muscle length and contraction patterns, resulting in a higher risk of strain injuries.
Nonetheless, calf muscle strains have also been reported to occur during slow, prolonged muscle movements, such as ballerina moves, but also during everyday activities. 
A strained calf muscle can affect a variety of sports including football, tennis, track and field, and dance. In football, 92% of injuries are muscular injuries, of which 13% are calf injuries.  In Australian Rules Football, CMSI represents one of the highest rates of soft tissue injury (3.00 per club per year) and had a 16% recurrence rate. 
It is important to differentiate muscle strains within the calf complex in order to develop a correct prognosis, appropriate treatment plan, and prevent recurrent injury. 
Calf strains most commonly occur on the medial head of the gastrocnemius muscle.  Sudden pain in the lower leg, and patients often report an audible or palpable popping sound on the inside of the back of the lower leg, or they have a sensation as if someone has kicked them in the back of the leg. Severe pain and swelling usually develop within the next 24 hours.  A gastrocnemius strain is also known as “tennis leg” because the classic presentation is a middle-aged tennis player suddenly straightening his knee. 
The gastrocnemius muscle is considered at high risk for strain because it crosses two joints (knee and ankle) and has a high density of type II fast-twitch fibers.  Tears of the medial head of the gastrocnemius muscle result from eccentric forces exerted on the muscle during knee flexion Extend and dorsiflex the ankle. The gastrocnemius muscle tries to contract while already stretched, causing the muscle to tear. 
Symptoms of a gastrocnemius strain include subjective reports of sudden, severe pain or a tearing sensation in the back of the calf, usually at the medial belly of the gastrocnemius muscle or at the tendon junction. 
An objective assessment would have :
- Tenderness at the injured point
- Bruising may appear within hours or days
- Stretching the muscle reproduces the pain
- Pain on resisted plantarflexion
The soleus muscle is injured when the knee is flexed. A strain of the proximal medial tendon junction is the most common type of soleus injury. Unlike the gastrocnemius, the soleus is considered a lower risk of injury. It only goes through the ankle and consists mainly of one type slow-twitch fibers. Soleus muscle strains also tend to be less clinically pronounced and more subacute than gastrocnemius injuries.  This condition frequently occurs in middle-aged patients who are in poor physical condition and/or are physically active. 
The presentation may resemble a gastrocnemius strain, but the pain may be slightly more distant and subjectively feel deeper. Soleus muscle injuries may be underreported due to misdiagnosis as thrombophlebitis or confusion of soleus muscle strains with gastrocnemius strains.  a A soleus strain causes pain when the calf muscle is activated or puts pressure on the Achilles tendon about 4 cm above the insertion point of the calcaneus or higher up the calf muscle. Stretching the tendon and walking on tiptoe can also worsen the pain. 
Although the plantaris also crosses the knee and ankle, it is considered primarily degenerative and is rarely involved in calf strains.  Plantaris rupture may occur at the tendon junction with or without associated hematoma or partial tear of the medial plantar head gastrocnemius or soleus.  Injuries to the plantaris can present with clinical features similar to those of the gastrocnemius and soleus muscles. 
Depending on the extent of the injury, individuals may be able to continue exercising despite some discomfort and/or tension during or after the activity. Where the injury is more severe, the exact mechanism of the injury is easier to recall and/or the individual may not be able to walk to excruciating pain.
Grading of calf strains
Muscle strains are graded from I to III, with grade III being the most serious. Treatment and rehabilitation depend on the severity of the muscle strain.
Grade Symptoms Signs Average time to return to activity I Severe pain during or after activity May be tight May be able to continue activity with no pain or slight discomfort Tightness and/or pain after activity Tightness and/or pain unilateral calf raising or pain when jumping 10- 12 Days II Severe Pain Calf movement time Unable to move around Significant pain after walking Muscles may swell Mild to moderate bruising may occur Pain with active plantar flexion Pain and weakness when plantar flexion is blocked Loss of dorsiflexion Painful calf elevation bilaterally 16 – 21 Day III Immediate severe pain often in the calf at the musculotendinous junction Cannot move further May be markedly bruised and swollen within hours of injury Cannot contract calf muscle May have significant defect Positive Thomson test 6 months after surgery
- Medial tibial stress syndrome (shin splints)
- Achilles tendinopathy
- Plantar fasciopathy
- Muscle strains and/or joint sprains due to decreased ankle ROM. 
- Other sports-related lower leg injuries that share the same symptoms and treatment as calf strains are discussed below.
- Chronic compartment syndrome (CECS).  CECS begins with mild pain during training that may go away after training. In later stages, pain comes on earlier, becomes more painful, and lasts longer, forcing activity to stop. Common complaints are; Cramps The calf feels unusually numb and weak. CECS is caused by increased intramuscular blood flow during exercise, so intercompartmental pressure rises, capillaries are compressed and ischemia develops.
- Popliteal artery compression syndrome (PAES). Abnormal relationship between popliteal artery and surrounding myofascial structures. Functional PAES is caused by muscle contraction, usually active plantarflexion of the ankle, compressing the arteries between the muscle and the underlying bone. 
- Baker’s cyst
- Subjective assessment and a thorough medical history should be performed at the point of initial assessment
- Objective assessment:
- Observation of the ankle while standing and lying on the back
- Ankle AROM
- Ankle PROM
- Calf palpation and symptom replication
- Resistance Strength Testing of the Foot and Ankle Complex
- Thompson test: rule out Achilles tendon rupture
- Knee AROM and resisted testing
- Ultrasound (US) is considered the gold standard. It can also be used to assess the extent and extent of muscle damage and to rule out other pathologies such as ruptured Baker’s cyst and deep vein thrombosis. 
Calf muscle tears are most common in sports that require rapid acceleration and changes in direction, such as running volleyball and tennis. Muscle strains are graded from grades I to III. The greater the stress, the longer the recovery time. Typical symptoms are stiffness, discoloration and surrounding bruising Pulled muscle. 
Grade I: Grade I or mild injuries are the most common and mildest. Severe pain from injury or pain with activity. With less than 10% muscle fiber destruction, there is little or no loss in strength and range of motion. Expect to return to motion within 1 to 3 minutes week. [twenty two]
Grade II: A grade II or moderate injury is when part of the muscle is torn and stops moving. Significant loss of strength and range of motion.  Accompanied by marked swelling pain and bruising. Between 10% and 50% muscle fiber disruption. 3 to 6 weeks is the usual recovery period to return to full condition Activity. 
Grade III: Third-degree or severe injury resulting in complete rupture of the muscle, usually with a hematoma.  Pain, swelling, tenderness, and bruising are usually present. Recovery is highly individualized and may take several months to fully recover and fully recover Activity. 
Rupture: Usually associated with the presence of fluid between the soleus muscle and the medial head of the gastrocnemius muscle. This may or may not be accompanied by bleeding. Measurement of fluid collection informs the extent of the lesion. Degree of disease (partial or complete rupture) can be defined by the distance between two muscles. Axial US scans are most useful for differentiating partial from complete ruptures because they can delineate the entire muscle belly in a single image. 
Calf strains rarely require surgery, but may be required when they rupture completely.
Conservative management includes:
- Soft tissue injury management
- Steroid injection
- If a hematoma is present, it must be removed as soon as possible or complications such as myositis ossificans may develop.
- If the injury is more severe, temporary heel pads can be used to shorten the calf muscles, reducing muscle tension while the muscles heal. However, it is recommended to have a heel pad on both shoes to avoid creating an unbalanced gait.
Physical Therapy Management
The mainstays of treatment for a calf strain include rest and allowing enough time to heal, but in severe cases, surgery may be necessary.
Conservative treatment consists of gentle passive isometric stretching followed by concentric exercises.  Massage and electrotherapy can be used in the later stage. 
Initial treatment aims:
- to limit bleeding
- prevent complications.
A soft tissue injury management program should begin immediately after the injury occurs. The principles of peace and love should be applied. [twenty four]
Other physical therapy modalities may be used, such as:
- Tape or compression wraps can be used and the leg can be elevated where possible. [twenty three]
- If major bleeding occurs, the use of NSAIDs must be carefully controlled because they have antiplatelet effects and can increase bleeding, as can premature application of heat and massage. 
- Gentle passive stretches that are painless and maintain the range of motion of the plantar flexors.  At later stages, once inflammation subsides, simultaneous application of surface heat and low-load static stretching can improve muscle flexibility. [twenty three]
- Isotonic exercises are recommended for the tibialis anterior and peroneal muscles, and light exercises for injured muscles. Gentle movement within pain limits in the first few days after injury will help promote healing 
- Low heel shoes are recommended to encourage improved heel gait. 
- When the calf muscles can be fully stretched without pain, it is possible to switch from gentle passive stretches to active stretches in the bent knee position (soleus) and straight knee position (gastrocnemius). [twenty three]
- Gradual loading/strengthening exercises should be given to the calf muscles to allow for full recovery. The earlier loading exercises are started, the faster recovery will be.
- Recovery exercises and specific plyometrics should begin prior to a full return to exercise.
Despite adequate early treatment, the strain can cause long-term pain. Treatment outcomes are successful when: Pain resolves Calf muscles can be fully stretched Strength returns to normal Knee and ankle ROM is normal and excessive tenderness disappears. [twenty three]
- LEFS: Lower Extremity Functional Scale
- VAS: Visual Analogue Scale
- NPRS: Numeric Pain Rating Scale
- Muscle Strength testing
Clinical Bottom Line
Calf muscle pain is often due to a strain, but there are other conditions that can cause similar symptoms, including deep vein thrombosis and Achilles tendinopathy or rupture. Healing time varies widely, depending on the severity of the strain and the individual’s response to treatment.
Conservative management consisting of a graded exercise program usually has satisfactory results for Grade I and II strains, but surgery is required in cases of rupture. Strength and conditioning training is essential to reload tissues and facilitate recovery activities.
- ↑ Wikimedia Commons contributors, “File:1123 Muscles of the Leg that Move the Foot and Toes b.png,” Wikimedia Commons, the free media repository, https://commons.wikimedia.org/w/index.php?title=File:1123_Muscles_of_the_Leg_that_Move_the_Foot_and_Toes_b.png&oldid=276846515 (accessed July 25, 2018).
- ↑ Jump up to:2.0 2.1 2.2 2.3 Green B, Pizzari T. Calf muscle strain injuries in sport: a systematic review of risk factors for injury. British journal of sports medicine. 2017 Aug 1;51(16):1189-94.
- ↑ Abe T , Fukashiro S , Harada Y , et al . Relationship between sprint performance and muscle fascicle length in female sprinters. J Physiol Anthropol Appl Human Sci 2001;20:141–7.
- ↑ Jump up to:4.0 4.1 Bengtsson H, Ekstrand J, Hägglund M. Muscle injury rates in professional football increase with fixture congestion: an 11-year follow-up of the UEFA Champions League injury study. British journal of sports medicine. 2013 Aug 1;47(12):743-7.
- ↑ Jump up to:5.0 5.1 5.2 5.3 Brukner P, Khan K. Clinical sports medicine.3rd ed. Sydney: McGraw Hill, 2006.
- ↑ Jump up to:6.0 6.1 Palastanga N, Field D, Soames R. Anatomy and human movement: structure and function. 5th Ed.Edinurgh: Elsevier,2006.
- ↑ Jump up to:7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 Dixon JB. Gastrocnemius vs. soleus strain: how to differentiate and deal with calf muscle injuries. Current reviews in musculoskeletal medicine. 2009 Jun 1;2(2):74-7.
- ↑ Jump up to:8.0 8.1 8.2 Spina AA. The plantaris muscle: anatomy, injury, imaging, and treatment. The Journal of the Canadian Chiropractic Association. 2007 Jul;51(3):158.
- ↑ Pull MR, Ranson C. Eccentric muscle actions: Implications for injury prevention and rehabilitation. Physical Therapy in Sport. 2007 May 1;8(2):88-97.
- ↑ Bryan Dixon J. Gastrocnemius vs. soleus strain: how to differentiate and deal with calf muscle injuries. Current Reviews in Musculoskeletal Medicine. 2009;2(2):74-77. doi:10.1007/s12178-009-9045-8. [L1b]
- ↑ Kwak H-S, Han Y-M, Lee S-Y, Kim K-N, Chung GH. Diagnosis and Follow-up US Evaluation of Ruptures of the Medial Head of the Gastrocnemius (“Tennis Leg”). Korean Journal of Radiology. 2006;7(3):193-198.
- ↑ Watura C, Harries W. Isolated tear of the tendon to the medial head of gastrocnemius presenting as a painless lump in the calf. Case Reports. 2009 Jan 1;2009:bcr0120091468.
- ↑ Jump up to:13.0 13.1 13.2 Flecca D, Tomei A, Ravazzolo N, Martinelli M, Giovagnorio F. US evaluation and diagnosis of rupture of the medial head of the gastrocnemius (tennis leg). Journal of ultrasound. 2007 Dec 1;10(4):194-8.
- ↑ Jump up to:14.0 14.1 14.2 14.3 Ellen, Mark I., Jeffrey L. Young, and James L. Sarni. “3. Knee and lower extremity injuries.” Archives of physical medicine and rehabilitation 80.5 (1999): S59-S67.
- ↑ Meininger, Alexander K., and Jason L. Koh. “Evaluation of the injured runner.” Clinics in sports medicine 31.2 (2012): 203-215.
- ↑ Knight CA., et al. (juni 2001). “Effect of Superficial Heat, Deep Heat, and Active Exercise Warm-up on the Extensibility of the Plantar Flexors.” Physical Therapy, Vol 81 (6), pp. 1206-1214.
- ↑ Ellen, Mark I., Jeffrey L. Young, and James L. Sarni. “3. Knee and lower extremity injuries.” Archives of physical medicine and rehabilitation 80.5 (1999): S59-S67.
- ↑ Stager, Andrew, and Douglas Clement. “Popliteal artery entrapment syndrome.” Sports Medicine 28.1 (1999): 61-70.
- ↑ Marc Roig Pull and Craig Ranson, Eccentric muscle actions: Implications for injury prevention and rehabilitation, Physical Therapy in Sport 8 (2007), no. 2, 88 – 97.
- ↑ Dixon JB. Gastrocnemius vs. soleus strain: how to differentiate and deal with calf muscle injuries. Current reviews in musculoskeletal medicine. 2009 Jun 1;2(2):74-7.
- ↑ prohealthsys. Gastrocnemius Muscle Test Vizniak. Available from: https://www.youtube.com/watch?v=kDU1J1kCMhk last accessed [19.09.2017]
- ↑ Jump up to:22.0 22.1 22.2 Nsitem V. Diagnosis and rehabilitation of gastrocnemius muscle tear: a case report. The Journal of the Canadian Chiropractic Association. 2013 Dec;57(4):327.
- ↑ Jump up to:23.0 23.1 23.2 23.3 23.4 23.5 23.6 Pedret C, Rodas G, Balius R, Capdevila L, Bossy M, Vernooij RW, Alomar X. Return to play after soleus muscle injuries. Orthopaedic journal of sports medicine. 2015 Jul 22;3(7):2325967115595802.
- ↑ Dubois B, Esculier JF. Soft-tissue injuries simply need PEACE and LOVE.
- ↑ Jump up to:25.0 25.1 Bartholdy C, Zangger G, Hansen L, Ginnerup‐Nielsen E, Bliddal H, Henriksen M. Local and systemic changes in pain sensitivity after 4 weeks of calf muscle stretching in a nonpainful population: A randomized trial. Pain Practice. 2016 Jul;16(6):696-703.
- ↑ AskDoctorJo. Calf pain or strain stretches & exercises. Available from: https://www.youtube.com/watch?v=XibsfBav_04 Last accessed [29.09.2017]