What is the Achilles Tendon?

What is the Achilles Tendon?

The Achilles tendon is the tough connective tissue that attaches the calf muscles to the heel bone. The Achilles tendon is the strongest tendon in the body, making it possible for people to walk, run, and jump. The Achilles tendon can be overused, injured, or even torn if it is overstretched.

Types of Achilles Tendon Pain


The two different types of Achilles injuries are:

  • Acute Achilles tendon rupture. If the Achilles tendon ruptures, you may hear a popping sound, followed by a sharp pain in the back of the ankle that travels up your calf
  • Chronic Achilles tendonitis. Tendonitis of the Achilles tendon happens from overuse or damage. It causes pain, inflammation, and swelling of the Achilles tendon.
    • Non-insertional Achilles tendonitis. The tendon begins to break down because of small tears in the middle fibers. Runners are commonly affected by this type of tendonitis if they suddenly increase their distance or duration of running.
    • Insertional Achilles Tendonitis. This type of tendonitis occurs when the tendon connects to the heel bone. Bone spurs (excessive bone growth) are common with this condition.

Signs & Symptoms of Achilles Tendon Pain


Achilles tendon injuries among young people are usually a result of overuse—long-distance walking, running or participating in recreational sports. Tight calf muscles and weak ankles may play a role as well. Often, middle-aged adults with arthritis may develop tendonitis.

Typical symptoms of Achilles tendon injuries include:

  • Pain in the back of the leg or above the heel after physical activities
  • Pain and tenderness, especially in the morning and wearing flat shoes or barefoot
  • Pain in the Achilles tendon when touched
  • Swelling in the tendon area
  • Difficulty standing or putting weight on the leg

More to explore

What Causes Achilles Tendon Pain?


Achilles tendon pain can occur when a person suddenly increases doing an activity that requires intense or repetitive physical motion. This abrupt increase in movement, especially without proper stretching exercises, can strain the Achilles tendon excessively.

Overuse and strain can be caused by increased walking, running, or any activity that requires the calf muscle and tendon to push off motion.

Risk Factors for Achilles Tendon Pain

Risk Factors

Possible risk factors could make a person more susceptible to developing Achilles tendonitis. These include:

  • Age. Older adults who participate in recreational sports, as in “weekend warriors”
  • Prior injury to the leg. Having a previous fracture or injury to the lower leg
  • Weight. Being overweight can increase a person’s risk of Achilles tendon disorders
  • Alcohol use. Moderate to high alcohol use can increase the risk of Achilles tendonitis
  • Smoking. People who smoke have an increased risk for poor healing of tendonitis, making them more susceptible to ruptured Achilles tendon
  • Physical activity. Suddenly increasing physical activity without proper warm-up exercises or overexertion playing sports when normally having a sedentary lifestyle can increase a person’s risk for Achilles tendon injuries
  • Flat feet. Being flat-footed can increases the risk of Achilles tendon injuries
  • Antibiotic use. Some high-dose antibiotics have been associated with acute tendon injuries

Sports that require running and jumping, such as tennis, basketball, soccer, and other high-intensity sports, can increase a person’s risk of developing Achilles tendon pain. Men have a higher risk of Achilles tendonitis than women. This difference is possibly gender-related. Female hormones, such as estrogen, may reduce the chance of Achilles tendon ruptures in women.

Certain medications, such as oral steroids used to treat rheumatoid arthritis, lupus, gout, and chronic renal failure, increase a person’s risk of acquiring tendonitis. In addition, certain antibiotics, such as ciprofloxacin, are associated with drug-induced tendonitis.



Preventing an Achilles tendon injury relies on a person honestly evaluating their true abilities before participating in strenuous activities. Some ways to avoid Achilles tendonitis include:

  • Stretch your calf muscles before exercising and playing sports
  • Vary your workout. Change up between high-impact exercise like running to low-impact exercise like swimming or walking. Avoid running uphill or jumping, which puts stress on the tendon.
  • Wear the right shoes. Running on hard surfaces, especially during cold weather, can aggravate your tendons. Wear well-fitting shoes with proper cushioning.
  • If you are experiencing pain during an activity—stop. Take a rest or discontinue the activity altogether.
Get Care

Trust NewYork-Presbyterian for Achilles Tendon Care

If you are experiencing pain in your calf or ankle area, it could be an indication of Achilles tendonitis. NewYork-Presbyterian and Columbia Orthopedics retain some of the most brilliant doctors in orthopedic medicine. Our physicians specialize in Sports Medicine and orthopedic treatments for professional athletes and everyday people.

Learn about the treatments available when dealing with an Achilles tendon injury or any other orthopedic condition you may be concerned about.