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A runner’s guide to calf strain injury: Part 1

Calf strain injury
Kim Van Deventer
Kim Van Deventer
Aug 16, 2021
This 2-part series provides a complete rundown of calf strain, including what symptoms you shouldn’t ignore, how to grade a calf injury, and a step-by-step guide on how to treat it.

What is a calf strain?

A calf strain is when some of the muscles at the back of your lower leg tear. This usually happens during activities like running, jumping, changing directions, or in some cases, miss-stepping on uneven surfaces.

Which muscles get injured in calf strain?

Your calves consist of deep and superficial muscles. In calf strain, the focus is on the superficial muscles. These include:

  • The Gastrocnemius muscle – its main function is to bend your knee and point your foot down.
  • Soleus muscle – its main function is to stabilize your lower leg and point your foot down.

Anatomy of the calf muscles and Achilles tendon.

The Gastrocnemius gets injured more often than the Soleus because it crosses over more joints and takes on more of the load during movement.

The Gastrocnemius and Soleus muscles taper down to the base of your calf and join to form a single structure, the Achilles tendon, which inserts into your heel bone.

This muscle-tendon complex acts as a pulley system – pulling your heel up, pointing your foot down, and moving your body forward.

What happens inside the muscle when it’s strained?

Skeletal muscles (the ones that move you) are made up of muscle cells, bunched together to form muscle fibers.

Skeletal muscle structure

When you strain a muscle, it means the muscle fibers are stretched or torn, either partially or completely.

In a partial tear, some fibers stay intact and the muscle can still function to some degree. In complete tears, the muscles can’t contract properly because the fibers are no longer joined.

What does a calf strain feel like?

Many people report feeling a sudden sharp pain in the calf, like something hitting them on the back of their leg, and not being able to continue with activity straight after the injury.

Common signs and symptoms of calf strain are:

  • A tight, tender or weak calf muscle
  • Spasms or cramping sensations in the calf muscle
  • A snapping or popping sound when the injury occurred
  • A sudden sharp pain in the back of the lower leg that gets worse with movement
  • Pain in your calf when you’re at rest
  • Bruising in the calf muscles
  • Swelling in the calf

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When should you see a doctor for your calf strain?

You should get your injury assessed by a medical professional if:

  • You heard a pop or felt a heavy blow to the back of the heel
  • You have pins and needles or tingling in your leg after your injury
  • You have severe pain, swelling or bruising
  • Your symptoms keep getting worse
  • Your symptoms keep you awake at night or disturb your sleep
  • Your injury isn’t getting better in the expected healing timeframes
  • Your leg is swollen, red, hot to touch or throbbing

See a doctor immediately if:

If your leg is hot to touch, swollen, red or throbbing – with or without history of injury – you should see a doctor immediately to rule out a DVT (blood clot).

How do we grade calf muscle strain?

Calf strains are graded in the same way as we grade any other muscle strain. There are a few different grading systems that you can use, but for most people the simplest (described below) works best.

Grades of muscle Strain

Muscle strains are classified as mild, moderate or severe (grade1, 2, and 3) according to the number of muscles fibers involved, severity of your symptoms, and how the injury affects your function.

By understanding these grades, you’ll be able to make better treatment or training choices.

Grades of muscle strain

    • 1st degree, mild
    • Mild pain, spasm, localised tenderness, swelling
    • Minimal loss of function
    • Able to continue activity
    • 3rd degree, severe
    • Immediate severe pain, palpable defect or mass
    • Complete loss of muscle function
    • Disability
    • 2nd degree, moderate
    • Moderate pain, spasm, tenderness, bruising, swelling
    • Clear loss of function
    • Unable to continue activity

What’s the difference between a pulled calf, calf strain or torn calf?

Clinically, there’s no clear link between a pulled calf, calf strain or a torn calf and the grades of muscle injury.

Many people describe a minor calf injury as a ‘pulled calf’ or ‘calf strain’, and a more severe injury, as a ‘torn calf’. We like to avoid confusion and name injuries according to their grades (I, II or III).

How and why do calf muscles get injured?

Calf muscles get injured in the same way as any other skeletal muscle. When pushed beyond their limits of stretch or strength, their muscle fibers tear.

For example, if you move too quickly, change direction suddenly, or add too much weight during exercise – your muscles will be overstretched or overloaded, causing injury.

The British Medical Journal reviewed the risk factors for developing calf injuries and found that age and previous calf injury are the highest risk factors for calf strain injury. 

Common causes of calf strain include:

  • Overtraining
  • Fatigue
  • Sudden increases in running intensities and volume
  • Weak calf, lower back and core muscles
  • Previous calf strain
  • Insufficient warm-ups
  • Increased age

Now that we’ve answered the ‘why and how’ behind the causes of calf strain, we can move onto how muscles heal, how to treat calf strain effectively and prevent it from happening again.

How long does it take for a calf muscle to heal?

Depending on the severity of your calf injury, and the treatment you receive, it can take between four weeks and six months, for a calf strain to heal completely.

A muscle strain healing time guide:

Depending on the severity of your calf injury, and the treatment you receive, your calf strain may need a few weeks to heal.
Grade I
4 – 6 weeks
Grade II
8 – 12 weeks
Grade III
4+ months


It’s important to remember that everyone is different, and every injury is unique. Timelines vary according to your case history and how many muscles and tendons are involved.

How do calf strains heal?

Research shows that skeletal muscles heal in a well-coordinated way. The three main phases of muscle healing are:

  1. Inflammatory Phase – The body cleanses the injury site of injured cells
  2. Regeneration Phase – New muscle cells are formed
  3. Remodeling Phase – The new muscle cells grow stronger

We explain this process in more detail in this article about how muscle strains heal.

The main point to remember when treating calf strain is treatment should support each phase of the healing process. If you push a muscle to work too hard before it’s healed, it may not be strong enough and you will be vulnerable to re-injury.

Start your rehab

The Exakt Health app aligns your calf strain recovery with the phase of healing your injury is in, and helps you progress safely and effectively through each stage.

What is the best way to treat calf strain?

Calf strains respond well to a careful balance of relative rest and progressive exercises. The trick is knowing what to do and when!

Relative rest

Relative rest means that you don’t necessarily have to stop all your activities. You just have to reduce their volume or intensity to a level that does not aggravate your injury. By how much you have to reduce it, will depend on the severity of your calf strain.

Progressive exercise program

Following a carefully graded exercise program is the other key component of any successful calf strain rehab plan, because it is only through strength training that your muscles can rebuild the strength they had before they got injured.

Because injured muscles aren’t very strong, the exercise program has to start out easy. However, to regain full strength, the exercises must progress in intensity and complexity as your calf strain heals. We discuss this process in detail and provide examples of exercises in the second article of this series, Calf Strain Part 2.

To ensure that your rehab exercises are set at the right intensity, the Exakt Health app asks for feedback about pain and effort after each workout.

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What more can you do to help heal calf strains?

The following modalities aren’t essential, but can be used to support your recovery alongside your progressive strengthening program:

  • Sports Massage helps with mental wellness, reduces pain and keeps muscles relaxed
  • Foam rolling can reduce muscle stiffness
  • Electrotherapy may help with reducing pain
  • Medications (avoid NSAIDs) help manage pain
  • Kinesiology Taping can reduce pain, bruising and swelling

How can you prevent calf strains?

A calf muscle strains when you load it with more force than it can bear. The British Journal of Sports Medicine produced this video explaining the concepts of Load vs. Capacity and how this relates to injuries.

It shows how we can prevent injuries by preparing the muscles better for activity, managing the forces that go through our bodies better, and allowing enough time for recovery.

Our 5 tips for preventing calf muscle strains:

Top tips for preventing a calf injury

Do a thorough warm-up before more intense training sessions.
Strength training
Add regular strength training to your schedule.
Training intensity
Avoid sudden changes in training volume and intensity.
Core strength
Maintain a strong core.
Add proper rest and recovery time to your training schedule.

What now?

Now that you have a good understanding of what a calf strain is and what the best treatment is, we suggest that you dive into Part 2 and learn how a progressive exercise plan works.

How to treat your calf strain?

Kim Van Deventer
Kim Van Deventer
Kim Van Deventer is a freelance healthcare writer and digital content strategist for healthcare businesses and medical content agencies. She has a BSc in Physiotherapy and worked as a physiotherapist for more than 14 years, specializing in sports injury rehabilitation, chronic pain management, and women's health. Kim combines her clinical experience and digital marketing skills to create relevant and helpful content that improves patients' lives.
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