Achilles tendon injuries

Think of the Achilles tendon as a shock absorber for your body when running, helping your foot move with the demand of body weight and activity. The faster your running speed, the greater the force developed – up to five times your body weight. The Achilles slows the descent of the heel as your body weight forces the load through the tendon while your calf muscles contract.

Breakdown occurs when the demand exceeds the tissue’s ability to adapt. In the case of the Achilles, this is known as tendinitis.

When the fibers of the Achilles become over-stressed, they can come apart, releasing chemicals that result in inflammation. When all of these fibers fail, the Achilles tendon ruptures and will no longer function.

What causes an Achilles tendon injury in runners?

  • Overtraining. Increasing mileage too quickly, or excessively loading the tendon with high intensity training when performing interval or sprint sessions.
  • Changing footwear. Changing types of running shoes can impact how you run such as when you switch to a minimalist shoe from a more supportive platform.
  • Changing running surfaces. Switching from hard pavement to a forest trail can create different stressors for your muscles.

The Achilles tendon is the extension of soft tissue covering the calf muscles, gastrocnemius and soleus; it consists of fibers that form its structure.

What are the signs and symptoms of an Achilles injury for runners?

  • Stiffness.
  • Pain when pushing-off walking or running.
  • Tenderness when applying finger pressure.
  • Symptoms decrease after warming up.
  • Symptoms increase the day after the aggravating activity such as a long run or high intensity run.

When to Seek Care for an Achilles Injury

It’s important to seek care when you notice pain and symptoms do not improve. Continued stressors can aggravate tendon fibers, cause chemical substances to accumulate, increase inflammation and irritate nerve endings; all of which can significantly impact running both short and long term.

The Achilles initiates healing by laying down scar tissue to repair the damage. However, scar tissue is not as strong as the original tendon tissue. When force is applied to an Achilles tendon with scar tissue, the nerve endings produce additional pain.

After the inflammation has dissipated, the tendon must be strengthened. This is generally best performed under the supervision of a healthcare provider such as a physical therapist familiar with Achilles tendon injuries.

How to Prevent and Protect the Achilles Tendon

  • Stretch. Develop a routine before and after you run, taking time to stretch.
    Tip: Try heel raises and calf stretches.
  • Cross train. Vary your routine by adding activities such as strength training, yoga or swimming. Cross-training can increase areas of fitness for running such as flexibility, balance, mobility and strength.
    Tip: Try this quick, high-intensity workout -- no membership or fee required.
  • Recover. Adequate recovery following long or high intensity runs is essential for your muscles. When you don’t allow adequate recovery time, tissues will break down faster than your body can recover.
    Tip: Plan easy days after long runs or high intensity workouts.
  • Increase mileage gradually. Gradually increase mileage and training intensity to adapt to new stresses.
    Tip: Increase mileage or training intensity by no more than 5 percent of your training level each week.
  • Select smart shoes. Allow time to adapt to new shoes and surfaces. A temporary reduction in mileage will allow gradual adaptation without derailing your training.
    Tip: Don’t use your long run to try out a pair of new shoes.

Run happy, run smart, run injury-free.


May 13, 2016 | by James McGavin PT, MSc, DipMDT