Achilles Tendonitis vs Plantar Fasciitis: Two Common Causes of Heel Pain
Understanding the key differences between Achilles Tendonitis and Plantar Fasciitis
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⚡ Quick Summary
Achilles tendonitis = pain at the BACK of the heel/lower calf (thickened tendon, worst after activity, treated with eccentric heel drops — NEVER inject the tendon). Plantar fasciitis = pain at the BOTTOM of the heel (sharp first-step morning pain, treated with calf stretching and supportive shoes — injection is a valid option). Both share a root cause: tight calf muscles. Stretching the calves helps both conditions.
Overview
[Achilles tendonitis](/condition/achilles-tendonitis) and [plantar fasciitis](/condition/plantar-fasciitis) are the two most common causes of heel pain, and they are anatomically connected — the Achilles tendon, calf muscles, and plantar fascia form a continuous biomechanical chain. Tight calf muscles contribute to BOTH conditions. The key distinction: Achilles tendonitis causes pain at the BACK of the heel, while plantar fasciitis causes pain at the BOTTOM of the heel. Understanding which condition you have is essential because some treatments help one but can worsen the other.
Key Differences at a Glance
| Feature | Achilles Tendonitis | Plantar Fasciitis |
|---|---|---|
| Pain Location | BACK of the heel and lower calf — along the Achilles tendon (2-6 cm above the heel for mid-portion; at the heel attachment for insertional) | BOTTOM of the heel — at the medial calcaneal tubercle, where the plantar fascia attaches to the heel bone; may extend along the arch |
| Morning Pattern | Morning stiffness in the tendon — first few steps are stiff, loosens quickly; pain may WORSEN as the day progresses with activity | HALLMARK: intense stabbing pain with first morning steps — worst pain of the day; IMPROVES after a few minutes of walking as the fascia warms up |
| Activity Response | "Warm-up phenomenon" — pain at the START of exercise, temporarily improves during activity, then worsens AFTER stopping (next-morning pain is common) | Pain improves during activity (after initial start-up pain) but worsens after PROLONGED standing or walking; pain after rest periods (post-static dyskinesia) |
| Palpation | Tenderness when SQUEEZING the Achilles tendon between fingers (pinch test); thickened, nodular tendon compared to the other side | Tenderness when PRESSING on the bottom of the heel (medial calcaneal tubercle); no tendon thickening; pain with toe dorsiflexion stretching the fascia |
| Who Is Most Affected | Active individuals — runners (6-17% lifetime incidence), men 6x more than women, ages 30-50 ("weekend warriors") | Both active and sedentary individuals — runners AND people who stand all day; equal sex distribution; peak ages 40-60; obesity (BMI >30) is major risk factor |
| Key Treatment Difference | Eccentric heel DROPS (Alfredson protocol — lowering below step level) are the gold standard; AVOID corticosteroid injection into the tendon (rupture risk) | Calf STRETCHING is the gold standard; corticosteroid injection is a valid treatment option (into the fascia, not tendon); night splints effective |
Symptoms Comparison
Symptoms Both Share
- • Heel pain that affects walking and running
- • Morning stiffness in the foot/ankle area
- • Pain worsened by activity and prolonged weight-bearing
- • Associated with tight calf muscles
- • Common in runners and active individuals
- • Gradual onset — rarely from a single injury
Achilles Tendonitis Specific
- • Pain at the BACK of the heel and lower calf
- • Thickened, swollen, nodular tendon visible and palpable
- • Pain with calf raises — rising on toes
- • Crepitus (creaking) when moving the ankle
- • Pain may INCREASE throughout the day with activity
- • Pain after exercise — "morning after" stiffness
Plantar Fasciitis Specific
- • Pain at the BOTTOM of the heel — sharp, stabbing quality
- • Worst pain with first morning steps — the hallmark symptom
- • Pain IMPROVES with walking after initial start-up
- • Pain after sitting for prolonged periods then standing
- • No visible tendon swelling
- • Pain with dorsiflexion of the toes (stretching the fascia)
Causes
Achilles Tendonitis Causes
- • Sudden increase in running mileage or intensity (>10% weekly)
- • Tight calf muscles restricting ankle dorsiflexion
- • Age-related tendon degeneration (peak 30-50)
- • Male sex — 6x higher risk than women
- • Running on hard surfaces or cambered roads
- • Previous Achilles injury (27-50% recurrence rate)
- • Fluoroquinolone antibiotics increasing tendon vulnerability
Plantar Fasciitis Causes
- • Tight calf muscles — the #1 modifiable risk factor (shared with Achilles tendonitis)
- • Excessive body weight — BMI >30 increases risk 5-6x
- • Prolonged standing or walking on hard surfaces
- • Flat feet or very high arches altering plantar fascia loading
- • Sudden increase in weight-bearing activity
- • Age-related degeneration of the plantar fascia (peak 40-60)
- • Worn-out or unsupportive footwear
Treatment Options
Achilles Tendonitis Treatment
- ✓ Eccentric heel drops (Alfredson protocol) — 3x15 reps, 2x daily, 12 weeks; gold standard (60-90% success)
- ✓ Reduce running volume by 50%+ — don't stop completely (controlled loading > complete rest)
- ✓ Heel lifts (1-1.5 cm) in both shoes to reduce tendon strain
- ✓ Ice after activity — 15-20 minutes
- ✓ Calf stretching — 30-second holds, 3x daily (straight AND bent knee)
- ✓ AVOID corticosteroid injection into the Achilles tendon — increases rupture risk 3-5x
- ✓ Shockwave therapy for chronic cases >3 months (60-80% effective)
Plantar Fasciitis Treatment
- ✓ Calf stretching — the MOST important treatment; 3x30 seconds, 3 times daily
- ✓ Plantar fascia-specific stretch — pull toes back to stretch the arch before getting out of bed
- ✓ Supportive footwear with cushioned heel and arch support
- ✓ Night splints — maintain plantar fascia stretch during sleep
- ✓ Corticosteroid injection — a valid option (into the fascia insertion, not the Achilles tendon)
- ✓ NSAIDs and ice after prolonged standing for pain relief
- ✓ Shockwave therapy for chronic cases >6 months (70-80% effective)
How Long Does It Last?
Achilles Tendonitis
Acute: 2-6 weeks with load management and eccentric exercises. Chronic tendinopathy: 3-6 months of structured rehabilitation. 75-80% resolve conservatively. Chronic cases (20-25%) may need surgery.
Plantar Fasciitis
80-90% resolve within 6-12 months with consistent conservative treatment. Most improve significantly within 6-8 weeks of stretching. About 5-10% become chronic (>12 months). Surgery is a last resort.
When to See a Doctor
Seek medical attention if you experience any of the following:
- ⚠️ Heel pain lasting more than 2-3 weeks despite home treatment
- ⚠️ A sudden "pop" at the back of the ankle with inability to push off (possible Achilles rupture — emergency)
- ⚠️ Pain preventing normal walking or daily activities
- ⚠️ Heel pain not responding to stretching and activity modification after 4-6 weeks
- ⚠️ Visible swelling, bruising, or deformity of the heel or tendon area
- ⚠️ Pain in both heels simultaneously — may suggest systemic cause
- ⚠️ Taking fluoroquinolone antibiotics with new Achilles pain — contact doctor immediately
Frequently Asked Questions
Frequently Asked Questions about Achilles Tendonitis vs Plantar Fasciitis
Click on a question to see the answer.
Yes — and this is the key biomechanical connection. The calf muscles (gastrocnemius/soleus), [Achilles tendon](/condition/achilles-tendonitis), and [plantar fascia](/condition/plantar-fasciitis) form a continuous chain. Tight calves increase strain on BOTH the Achilles tendon (pulling on it from above) and the plantar fascia (increased forefoot loading from restricted dorsiflexion). This is why calf stretching is a cornerstone treatment for both conditions. You can actually have both simultaneously — about 10-15% of runners with one condition develop the other.
**Touch test**: Squeeze the Achilles tendon between your fingers 2-6 cm above the heel — if tender and thickened, it's [Achilles tendonitis](/condition/achilles-tendonitis). Press on the BOTTOM of your heel (where the arch meets the heel) — if that's where it hurts, it's [plantar fasciitis](/condition/plantar-fasciitis). **Morning test**: If first-step stabbing pain that quickly improves → plantar fasciitis. If general stiffness that loosens then worsens with activity throughout the day → Achilles. **Calf raise test**: Pain going up on toes → Achilles.
Be cautious. The Alfredson eccentric heel drops (lowering the heel BELOW step level) deeply stretch the calf AND plantar fascia. If you have primarily [Achilles tendonitis](/condition/achilles-tendonitis), this is the gold standard treatment. But if you also have active [plantar fasciitis](/condition/plantar-fasciitis), the deep stretch at the bottom position may aggravate it. Solution: do the eccentric drops but DON'T lower below the step level initially — keep the heel level with the step until the plantar fascia calms down. Then gradually increase the range.
Medical Disclaimer
The information on this page is for educational purposes only and is not intended as medical advice. It should not be used for self-diagnosis or self-treatment. Always seek the guidance of a qualified healthcare professional with any questions you have regarding a medical condition. If you are experiencing a medical emergency, call your local emergency services immediately.