The most likely reason your heel hurts after running is plantar fasciitis, a condition where the thick band of connective tissue along the bottom of your foot develops small tears and becomes inflamed. It accounts for up to 31% of running-related injuries. But several other conditions cause heel pain in runners, and the location and timing of your pain can help you figure out which one you’re dealing with.
Plantar Fasciitis: The Most Common Cause
Plantar fasciitis produces a stabbing pain on the bottom of your heel, slightly toward the inner edge. The hallmark symptom is pain with your first steps in the morning. You get out of bed, put your foot down, and feel a sharp jab that gradually loosens up as you walk around. The pain often improves during activity, then returns worse at the end of the day or after long periods of sitting.
What’s happening inside the foot is more wear-and-tear than inflammation, despite the name. The tissue where your plantar fascia attaches to your heel bone breaks down at a microscopic level. Repetitive impact from running, especially on hard surfaces like concrete or a treadmill, overloads the fascia faster than it can repair itself. The result is fragmentation and degeneration of the tissue at the attachment point.
Your shoe choice matters more than you might think. Shoes with a higher heel-to-toe drop (8 to 12mm) reduce tension on the plantar fascia, while minimalist or zero-drop shoes (0 to 4mm) increase it. If you recently switched to a lower-drop shoe or started running in worn-out trainers, that change alone could explain your pain. Podiatrists generally recommend shoes with at least 7mm of heel elevation for runners dealing with this condition.
Achilles Tendonitis: Pain at the Back of the Heel
If your pain is at the back of your heel rather than the bottom, the problem is more likely your Achilles tendon. This is the thick cord connecting your calf muscles to your heel bone, and it takes enormous force with every running stride. Runners are especially prone to overloading it.
There are two types. Insertional Achilles tendonitis causes pain right where the tendon meets the heel bone, low on the back of your foot. Non-insertional tendonitis hits higher up, in the middle portion of the tendon, a few inches above the heel. Both types tend to hurt more the day after a run rather than during it, and the pain gets progressively worse with continued activity over days and weeks. You may also notice stiffness and swelling along the back of the heel.
The key difference from plantar fasciitis: Achilles pain is behind the heel, plantar fasciitis pain is underneath it. If you can pinpoint the sore spot by pressing the back of your ankle just above the shoe line, that’s your Achilles.
Calcaneal Stress Fracture: Pain That Builds Over Weeks
A stress fracture in the heel bone is less common but more serious. The pain develops gradually over days to weeks, not overnight. It can show up along the bottom, sides, or back of the heel, which makes it easy to confuse with other conditions early on.
One way to check at home: squeeze both sides of your heel with your hand, compressing it like you’re pinching a hamburger bun. If that squeeze produces sharp pain, a stress fracture is a real possibility. This is called the squeeze test, and it’s one of the first things a clinician will do during an exam. Unlike plantar fasciitis, stress fracture pain doesn’t have that classic “worse in the morning, better after walking” pattern. It tends to hurt consistently with any weight-bearing activity and gets worse the more you run on it.
Stress fractures need imaging to confirm and require a genuine break from running, typically six to eight weeks. Continuing to train through one risks turning a hairline crack into a complete fracture.
Fat Pad Syndrome: A Bruised Feeling in the Center
Your heel has a built-in cushion: a pad of fatty tissue that absorbs shock every time your foot hits the ground. Over time, repetitive pounding can thin this pad or cause it to lose elasticity. Running on hard surfaces, wearing shoes without enough cushioning, or simply logging high mileage over years can all wear it down.
Fat pad syndrome feels like a deep bruise right in the center of your heel. This location is one of the clearest ways to distinguish it from plantar fasciitis, which sits closer to the inner edge of the heel and may extend into the arch. Fat pad pain also behaves differently. It tends to worsen with prolonged standing and high-impact activities, gets aggravated when you walk barefoot on hard floors, and is more likely to show up in both feet. Some people notice the pain more at night or at rest, which is the opposite of plantar fasciitis.
Bursitis: Swelling Behind the Heel
Bursae are small fluid-filled sacs that cushion the joints in your foot. When the bursa near your heel bone becomes irritated, it swells and creates a tender, bruise-like sensation at the back of the heel. This typically happens after spending a lot of time on your feet or from friction caused by stiff-backed shoes pressing against the heel. The area may feel warm or look slightly puffy compared to the other foot.
How to Tell These Conditions Apart
- Bottom of heel, inner side, worst first thing in the morning: plantar fasciitis
- Back of heel or just above it, worse the day after running: Achilles tendonitis
- Center of heel, deep bruise feeling, worse barefoot on hard floors: fat pad syndrome
- Diffuse heel pain that built up over weeks, hurts when you squeeze the sides: stress fracture
- Back of heel, puffy or warm, tender to touch: bursitis
What Helps Runners Recover
For plantar fasciitis, most people see improvement within 4 to 12 weeks with conservative measures. Acute cases (under six weeks of symptoms) often respond well to rest, stretching, and switching to better-cushioned shoes. If your pain has lasted longer than three months, it’s considered chronic and typically requires a more structured approach: physical therapy, custom orthotics, or other interventions.
One of the most effective exercises for plantar fasciitis is a heavy, slow heel raise. You stand on a step with your toes on the edge and a rolled towel under them to increase the stretch on the fascia, then slowly lower and raise your heel. Research on 12-week programs using this exercise, performed with progressively heavier loads (like wearing a backpack), shows significant improvements. The key is consistency and gradual loading, doing as many sets as you can manage with enough weight that you can complete no more than eight repetitions per set.
For Achilles tendonitis, the approach is similar: controlled loading through eccentric exercises (slowly lowering your heel off a step), reducing your running volume, and addressing any calf tightness. Both conditions respond poorly to complete rest with no exercise at all. The tendon and fascia need controlled stress to remodel and heal.
What to Reduce or Avoid
Running through worsening pain is the single biggest mistake. A small amount of discomfort during a run that doesn’t get worse and clears up within 24 hours is generally manageable. Pain that escalates during the run or lingers for days means you’re exceeding what the tissue can handle.
If steroid injections come up as a treatment option for plantar fasciitis, know the tradeoff. They can provide short-term relief, but they carry a 2.4% risk of plantar fascia rupture, typically after an average of about three injections. A ruptured fascia is a much longer recovery than the original problem.
Shoes and Surface Changes That Help
If you’re running primarily on concrete or asphalt, switching some runs to softer surfaces like trails, grass, or a track can reduce the repetitive load on your heel. This is especially relevant for fat pad syndrome and plantar fasciitis, where impact forces are the primary driver.
Check the mileage on your running shoes. Most trainers lose meaningful cushioning between 300 and 500 miles. If you can’t remember when you bought them, they’re probably due for replacement. For plantar fasciitis specifically, look for shoes in the 8 to 12mm heel drop range, which reduces tension on the fascia compared to flatter options. Avoid walking barefoot on hard floors at home, particularly first thing in the morning when the fascia is at its tightest. Keeping a pair of supportive sandals or slippers by the bed can make a noticeable difference in that morning pain.