It often starts quietly. The back of your heel feels stiff for the first few minutes of the morning, then loosens up. A few weeks later the stiffness lasts longer, stairs start to ache, and the thick cord above your shoe feels tender when you squeeze it. That pattern is typical of Achilles tendinopathy, one of the most common causes of pain at the back of the heel in active adults over 40.
What is happening inside the tendon
The Achilles is the largest tendon in the body. It connects your calf muscles to your heel bone and takes several times your body weight with every step, more on stairs and hills. When it is loaded harder or more often than it can adapt to, small areas of the tendon start to break down faster than they repair. The tendon can thicken, lose some of its organized structure, and become sore and stiff.
This is less about a sudden injury and more about a mismatch between demand and recovery. That is why it so often appears after a change: a new walking routine, a vacation with miles on hard pavement, a new job on your feet, or a return to a sport after time away.
Two places it tends to hurt
- Midportion tendinopathy: pain and sometimes a firm swelling a couple of inches above the heel, in the body of the tendon itself.
- Insertional tendinopathy: pain right where the tendon attaches to the back of the heel bone, often worse with shoes that press on that spot. It can come with a bony bump or an irritated fluid sac (bursa) nearby.
The difference matters, because the exercises and shoe changes that help one type can aggravate the other. Sorting out which you have is one of the first things a podiatrist will do.
Who is more likely to develop it
- Adults in their 40s, 50s and 60s, as tendons become less elastic.
- People with tight calves or flat or high-arched feet.
- Anyone who has recently increased walking, running or standing time.
- People with diabetes, high cholesterol or inflammatory arthritis.
- Those who have taken a class of antibiotics called fluoroquinolones, which can affect tendons. Do not stop a prescribed medication on your own, but do mention it at your visit.
A warning sign not to ignore
A sudden pop or the feeling of being kicked in the back of the leg, followed by difficulty pushing off or standing on your toes, can mean the tendon has torn. That needs prompt evaluation, ideally the same day, rather than a wait-and-see approach.
What helps
Tendons respond to the right kind of load. Complete rest tends to leave them weaker, while too much activity keeps them irritated. Treatment aims for the middle ground:
- A guided strengthening program for the calf and tendon, built up gradually over weeks. This is the backbone of care for most people.
- Adjusting activity rather than stopping it: shorter walks, flatter routes, fewer stairs for a while.
- Heel lifts or supportive shoes that reduce strain on the tendon, chosen to suit the type you have.
- Orthotics when foot mechanics are adding to the load.
- A walking boot for a short period during a painful flare.
- Other office-based therapies in selected cases. Injections directly into the Achilles are generally avoided because of the risk to the tendon.
Tendons heal slowly, and a realistic timeline is often a few months of steady work. Individual results vary, but people who stay consistent with their program tend to see the stiffness and soreness gradually loosen their grip.
When the pain will not move
Some cases stall despite good care, particularly long-standing insertional pain. Before anyone talks about surgery, your Heelex podiatrist can walk you through further non-surgical options, including low-dose radiation therapy through our affiliated radiation clinic, which is sometimes considered for persistent tendon and bursa pain that has not responded to standard treatment. Your podiatrist will help you weigh whether it fits your situation.
If the back of your heel has been stiff and sore for more than a few weeks, schedule a visit with our podiatry team in Knoxville. Getting the type and the plan right early can save you months of frustration.