Achilles tendinopathy is most often caused by:

• Overuse or repeated movements during sports, work, or other activities. In sports, a change in how long, intensely, or often you exercise, or a change in your environment (such as going from a flat surface to a hill or from a paved road to a dirt road) can cause microtears in the tendon that are unable to heal quickly and will eventually cause pain.
• Injury from repeated push-offs or a stop-and-go motion, common in such activities as running, basketball, tennis, or ballet dancing.
• Poor conditioning or warm-up (as when you start a new activity or have not stretched before and after an activity).
• Shoes with poor arch support or rigid heels that do not cushion the heel.

Achilles tendon rupture is most often caused by:

• Sudden, forceful motion that stresses the calf muscle, such as during an intense athletic activity or even during simple running or jumping, especially in middle-aged adults. A rupture most often occurs in sports such as basketball, racket sports (including tennis), soccer, and softball.¹
• Overstretching the tendon during any activity when the tendon is already damaged because of Achilles tendinopathy or another condition.
• Previous corticosteroid injections (in the past, a common treatment for overuse tendon injury). Corticosteroids can weaken or break down tendon tissue, making it more likely to rupture.