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Gastrocnemius and soleus
The two calf muscles that share the Achilles tendon and push you off the ground at every step.
Latin name: Musculus gastrocnemius et musculus soleus. In plain English, the calf muscles. It is filed here under lower leg and foot.
Reference information, not a diagnosis. Where a symptom is described below, it is there so you can describe your own more precisely to a clinician — not so you can name what you have.
Where it is
Gastrocnemius is the superficial calf muscle with the visible two-headed bulge; it arises above the knee, from the back of the femur. Soleus lies underneath it, broader and flatter, arising from the tibia and fibula below the knee. The two join into the Achilles tendon, which attaches to the back of the heel bone. Together they are sometimes called triceps surae, the three-headed muscle of the calf.
The difference in origin has a practical consequence you can feel. Because gastrocnemius crosses the knee, bending the knee slackens it, and a calf raise with a bent knee therefore shifts the load onto soleus. Straight-knee and bent-knee calf raises are genuinely different exercises for that reason.
| Feature | Detail |
|---|---|
| Gastrocnemius | Two heads from the posterior surfaces of the medial and lateral femoral condyles; crosses the knee as well as the ankle |
| Soleus | From the soleal line of the tibia and the posterior head and upper shaft of the fibula; crosses only the ankle |
| Insertion | Calcaneal (Achilles) tendon into the posterior calcaneus |
| Nerve | Tibial nerve (S1-S2) |
| Main actions | Plantarflexion of the ankle; gastrocnemius also flexes the knee; soleus is a key postural muscle in standing |
What it does
They push the foot down against the ground, which is the propulsive phase of every step, run and jump. Forces here are large: the Achilles tendon transmits several times body weight during running. They also decelerate the body — in each stance phase the calf lengthens under load before it shortens, storing and returning elastic energy through the tendon.
Soleus does the quieter work. It is rich in slow-twitch fibres and works continuously in standing to stop the body toppling forward over the ankles, which is why it fatigues in long standing rather than in sprinting. It is also part of the muscle pump that helps return venous blood from the leg, and it is by far the more heavily loaded of the two during running.
Exercises that load it
| Exercise | Category | Muscles the exercise library lists |
|---|---|---|
| Jump rope | Conditioning | Calves, shoulders, heart |
| Easy running (8 km/h) | Cardio | Legs, heart, lungs |
| Brisk walking (5.5 km/h) | Cardio | Legs, heart |
| Stair climbing | Cardio | Quads, glutes, calves, heart |
| Cycling (19-22 km/h) | Cardio | Quads, glutes, calves, heart |
Calf raises are the direct load: straight-knee for gastrocnemius, seated or bent-knee for soleus. Skipping and hopping load the tendon-muscle unit elastically at speed. Running loads it repeatedly at high force, and calf capacity is often the limiting factor for runners increasing their mileage. Heavy slow calf work is one of the better-supported interventions in Achilles tendon rehabilitation, but the specific protocol belongs to a clinician.
How it is lengthened
For gastrocnemius, a standing lunge against a wall with the back knee straight and the heel down. For soleus, the same position with the back knee bent. Both should be felt in the calf rather than under the heel; sharp pain at the heel or in the Achilles is a reason to stop and get advice.
When it goes wrong
| Problem | What it typically feels like | Usual setting |
|---|---|---|
| Calf strain | A sudden sharp pain in the calf, classically at the inner side, sometimes as if kicked | A push-off or sprint start; the medial head of gastrocnemius is the common site |
| Achilles tendinopathy | Morning stiffness and pain in the tendon a few centimetres above the heel, easing as it warms then returning after activity | A rapid increase in running volume, speed work, or a change of footwear |
| Calf cramp | A sudden involuntary painful contraction, often at night or late in exercise | Poorly understood; associated with fatigue and with new or intense exercise |
| Deep vein thrombosis | Unilateral calf pain with swelling, warmth and redness, not linked to any injury | A medical emergency, not a training problem |
Calf pain with swelling of the whole leg, warmth, or breathlessness needs urgent medical assessment — that pattern can mean a deep vein thrombosis. So does a sudden loud pop at the back of the ankle with an inability to push off, which can mean a ruptured Achilles tendon.
Nothing on this page is a treatment plan. If a problem is limiting what you do, is not improving, or is getting worse, the right next step is an assessment by a doctor or a physiotherapist who can examine you.
Sources: descriptive anatomy from Gray's Anatomy of the Human Body, 20th US edition (1918), which is in the public domain; Latin names follow Terminologia Anatomica, published by the Federative International Programme for Anatomical Terminology. Nerve root levels are the conventional ranges taught from those sources and vary between individuals and between textbooks. Exercise cross-links use the TempoLife exercise library. Checked 2026-09-06.
Frequently asked questions
What is the difference between gastrocnemius and soleus?
Gastrocnemius crosses the knee and the ankle and is the visible superficial muscle; soleus lies underneath, crosses only the ankle, and is the postural workhorse. Bending the knee slackens gastrocnemius and shifts load to soleus.
Why do I get calf cramps at night?
Nocturnal calf cramps are common and their cause is not well established. They are associated with fatigue and with age, and the popular explanations involving dehydration and electrolytes are not as well supported as commonly claimed.
Do I need to stretch my calves for running?
Static stretching before running has not been shown to prevent injury, and calf capacity matters more than calf length. Progressive calf strengthening is the better-supported approach to tolerating running load.
Nearby in this reference
Tibialis anterior
The shin muscle that lifts the foot
Deltoid
The cap of the shoulder
Rotator cuff
The four small muscles that hold the shoulder in its socket
Trapezius
The big diamond across the upper back and neck
Rhomboids
The straps that pull the shoulder blades together
Serratus anterior
The finger-like muscle on the ribs that pins the shoulder blade down
All 34 body parts · Exercise library · Body map
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