In Greek mythology, the hero Achilles was killed by an arrow to his heel, the only vulnerable spot on his otherwise invincible body. The story explains both his legendary death during the Trojan War and why we still use “Achilles heel” to describe a critical weakness. It also gave its name to the largest tendon in the human body, one that remains surprisingly prone to injury today.
The Myth: Thetis, the River Styx, and One Fatal Mistake
Achilles was the son of Thetis, a sea goddess, and Peleus, a mortal king. Thetis knew her son would be mortal because of his father’s bloodline, so she sought a way to protect him. She carried her infant son to the River Styx, the boundary between the world of the living and the underworld, and plunged him into its waters. The river’s power made his body immortal and invulnerable to weapons.
But Thetis had to hold him by something. She gripped him by the ankle, and that small patch of skin never touched the water. It remained ordinary, mortal flesh. This single overlooked spot became the most famous vulnerability in Western literature.
How Achilles Died at Troy
Achilles was the greatest warrior of the Greek army during the Trojan War, virtually unstoppable on the battlefield. He killed Hector, Troy’s champion, and fought his way to the very gates of the city. But in his final battle, Paris (a Trojan prince and far less skilled fighter) launched an arrow that struck Achilles directly in his unprotected heel. The god Apollo guided the arrow to its target. The mightiest warrior of the age was brought down not by a superior opponent, but by a single shot to his one weak point.
The story carried a deliberate moral: no one, however powerful, is without vulnerability. That theme resonated so deeply that by the 1830s, English speakers had turned “Achilles heel” into a common idiom. The earliest recorded use appeared in 1839, in the writing of Hartley Coleridge, and the phrase has been in steady use ever since.
The Tendon That Shares Its Name
The Achilles tendon runs down the back of your lower leg, connecting your calf muscles to your heel bone. It is the strongest and largest tendon in the human body, capable of bearing loads exceeding 3,500 newtons (roughly 787 pounds of force) during activities like running, jumping, and pushing off the ground. Its elastic, spring-like properties deliver the explosive propulsion behind nearly every movement that involves your feet.
Yet despite that tremendous strength, the Achilles tendon is frequently injured. The name turns out to be fitting: like the mythological hero, this powerful structure has a surprising vulnerability.
Who Gets Injured and Why
Achilles tendon ruptures have been rising in frequency. In 2024, the rate of surgical repairs in the United States was about 7.3 per 100,000 patients, a significant increase from 2015. Men aged 25 to 29 experience the highest rate of ruptures overall (about 61 per 100,000), while the peak for women occurs between ages 45 and 49 (about 23 per 100,000).
Several factors raise the risk. Middle-aged people face a peak incidence because the tendon gradually weakens as physical activity declines over the years. Obesity, high cholesterol, diabetes, and musculoskeletal disorders all contribute. Poor calf flexibility, stiff shoes, and muscle fatigue that causes the tendon to overstretch can trigger mechanical damage. Men are injured at roughly twice the rate of women.
Certain antibiotics in the fluoroquinolone family (commonly prescribed for urinary tract and respiratory infections) carry a well-documented risk of tendon damage. Patients over 60 who take these medications are nearly three times more likely to experience a tendon rupture compared to younger patients. Corticosteroid use compounds that risk further.
What a Rupture Feels Like
People who rupture their Achilles tendon typically describe a sudden pop or snap in the back of the lower leg, often during a quick push-off movement like sprinting or jumping. It can feel like being kicked or hit from behind. Walking becomes immediately difficult, and pointing the foot downward loses most of its strength. A doctor can confirm the injury with a simple calf-squeeze test (squeezing the calf muscle while the patient lies face down). If the foot doesn’t move, the tendon is likely torn. This test is highly accurate, catching about 96% of complete ruptures.
Surgery vs. Non-Surgical Recovery
Treatment for a complete Achilles rupture falls into two camps, and the best choice depends on the individual. A large meta-analysis of nearly 36,000 patients found clear tradeoffs between the two approaches.
Surgery cuts the re-rupture risk by more than half and increases the likelihood of returning to sports by about 32%. For competitive athletes or anyone whose livelihood depends on explosive lower-leg power, those numbers often tip the scale toward the operating room.
Non-surgical treatment (functional rehabilitation with a walking boot and structured physical therapy) carries a higher chance of re-rupturing the tendon. But it avoids the complications that come with surgery, including a nearly five-fold higher rate of superficial infection, a nearly two-fold increase in deep infection, and a 3.7-fold higher rate of nerve injury. For less active patients or those with health conditions that make surgery risky, conservative treatment produces similar long-term functional scores.
What Recovery Looks Like
Whether treated surgically or not, full recovery from an Achilles rupture takes 6 to 9 months, with return to sport often requiring 9 to 12 months. The process moves through distinct phases that gradually increase the demands on the healing tendon.
For the first two weeks after surgery, you bear no weight on the injured leg. By week two, you transition into a walking boot with heel lifts and begin putting weight on the foot with crutches. Most people ditch the crutches around week four. By week eight, you start weaning out of the boot entirely and walking in a supportive shoe, beginning standing heel raises (both legs at first, then progressing to the injured leg alone).
The real test comes around weeks 12 to 16, when running and jumping can begin, but only after meeting specific benchmarks: near-symmetrical range of motion compared to the uninjured side, normalized walking and jogging mechanics, and the ability to perform 25 single-leg heel raises at close to normal height. Return to competitive sport requires at least 90% symmetry between limbs on balance and hop testing, plus physician clearance. Rushing this timeline is one of the most common reasons people re-injure the tendon.