What Is Achilles Tendonitis?

The Achilles tendon is the largest tendon in the body, linking the calf muscles to the heel bone. It plays a vital role in walking, running, jumping, and standing on tiptoe. Achilles tendonitis (or tendinopathy) occurs when this tendon becomes irritated or inflamed, usually due to repetitive stress or sudden increases in physical activity.

Types

There are two main forms of Achilles tendonitis:

  • Noninsertional tendonitis: Small tears develop in the middle portion of the tendon, leading to swelling and thickening. This type is more common in younger, active individuals.

  • Insertional tendonitis: Involves the lower portion of the tendon where it attaches to the heel bone. Bone spurs may also form in this area, and it can affect both active and less active people.

Symptoms

Typical signs include:

  • Pain and stiffness along the back of the leg or above the heel

  • Swelling and tenderness around the tendon

  • Morning stiffness that improves with mild activity

  • Pain that worsens after running, climbing stairs, or sprinting

Causes and Risk Factors

Achilles tendonitis is usually caused by overuse or sudden increases in activity. Contributing factors include:

  • Running or jumping sports

  • Poor footwear or worn-out shoes

  • Tight calf muscles or flat feet

  • Age-related tendon weakening

  • Certain medications (such as fluoroquinolone antibiotics)

  • Medical conditions like diabetes or high cholesterol

Diagnosis

Diagnosis is based on a physical exam and may be supported by imaging tests such as X-rays, ultrasound, or MRI to assess tendon damage.

Treatment Options

Most cases can be managed without surgery:

  • Rest and activity modification (switching to low-impact exercise)

  • Ice, compression, and elevation (RICE method) to reduce swelling

  • Supportive footwear, heel lifts, or orthotics

  • Stretching and strengthening exercises for calf muscles

  • Physical therapy to improve flexibility and tendon health

  • Anti-inflammatory medications for pain relief

If symptoms persist for more than six months, surgical options such as tendon debridement, repair, or tendon transfer may be considered.

Outlook

With early treatment, most people recover well. However, untreated tendonitis can progress to Achilles tendinosis (degeneration) or even tendon rupture, which is a serious injury requiring surgery.

Prevention

Ways to reduce risk include:

  • Gradually increasing exercise intensity

  • Stretching calf muscles daily

  • Wearing supportive shoes and replacing worn-out footwear

  • Cross-training with low-impact activities like swimming or cycling

  • Allowing adequate rest between workouts