That nagging pain at the back of your ankle? Don't ignore it. Here's everything you need to know.

What Is Achilles Tendinitis?

The Anatomy

The Achilles tendon:

• Largest and strongest tendon in your body
• Connects calf muscles (gastrocnemius, soleus) to heel bone
• Handles forces of 6-8x body weight during running
• Essential for push-off and propulsion

Tendinitis vs. Tendinopathy

What we used to think: The tendon gets inflamed (tendinitis)

What we now know: Most Achilles issues involve tendon degeneration, not inflammation (tendinopathy)

Why this matters:

• Anti-inflammatory medications alone don't fix it
• The tendon needs load to heal, not just rest
• Active rehabilitation (eccentric exercises) is essential

Types of Achilles Issues

Insertional:

• Pain where tendon attaches to heel bone
• Often associated with bone spur
• More common in older runners

Midportion:

• Pain 2-6 cm above heel
• More common overall
• Often develops nodule or thickening

Both respond to similar treatment, though insertional may be more stubborn.

Causes and Risk Factors

Why the Achilles Fails

Training errors (most common):

• Sudden increase in mileage
• Adding hills or speed work too quickly
• Returning too fast after time off
• Not enough recovery between hard efforts

Biomechanical factors:

• Tight calf muscles
• Weak calf muscles
• Overpronation
• Limited ankle mobility

Equipment:

• Worn-out shoes
• Sudden shoe changes (especially drop height)
• Transitioning too fast to minimalist shoes

Who's at Risk

Higher risk if you:

• Are male (more common in men)
• Are over 40 (tendon becomes stiffer)
• Have had previous Achilles issues
• Recently increased training
• Have tight or weak calves
• Run on hills frequently

Symptoms and Diagnosis

Early Warning Signs

Don't ignore:

• Stiffness in the morning (first steps)
• Pain at start of run that "warms up"
• Tenderness when you squeeze the tendon
• Mild swelling around tendon

These are signals to reduce training and start prevention measures.

Progressive Symptoms

Getting worse:

• Pain during running that doesn't warm up
• Pain that persists after running
• Thickening or nodule in tendon
• Difficulty walking normally

This requires active treatment and likely time off from running.

Red Flags

See a doctor immediately if:

• Sudden sharp pain (possible tear)
• Popping sound with sudden onset pain
• Inability to point toes
• Significant swelling
• Gap you can feel in the tendon

These may indicate partial or complete rupture requiring urgent evaluation.

Self-Assessment

The pinch test:

Pinch the tendon between thumb and forefinger along its length. Tenderness at a specific spot suggests tendinopathy.

Morning stiffness:

If the first few steps each morning are painful or stiff for more than a week, take it seriously.

Treatment

Phase 1: Reduce Load (Weeks 1-2)

Modify activity:

• Stop running or reduce significantly
• Avoid activities that aggravate
• Walking should be pain-free; if not, consider heel lift

Pain management:

• Ice after activity (15-20 min)
• Over-the-counter pain relief if needed
• Avoid prolonged anti-inflammatory use (may impair healing)

Protect but don't immobilize:

• Heel lifts can reduce tendon strain
• Avoid barefoot walking initially
• Keep moving—complete rest slows healing

Phase 2: Load the Tendon (Weeks 2-12)

Eccentric heel drops—the gold standard:

Research strongly supports eccentric loading for Achilles tendinopathy.

Protocol (Alfredson protocol):

1. Stand on a step, heels hanging off
2. Rise up on both feet
3. Transfer weight to injured leg
4. Slowly lower heel below step level (3 seconds)
5. Rise back up on both feet

Dosage:

• 3 sets of 15 repetitions
• Twice daily
• Both straight leg (targets gastrocnemius) and bent knee (targets soleus)
• Progress by adding weight when pain-free

Expect mild discomfort during exercises (pain up to 5/10 is acceptable). Avoid if pain is severe.

Phase 3: Progress Loading (Weeks 6-12)

As symptoms improve:

• Bilateral calf raises → single leg calf raises
• Slow controlled → faster movements
• Bodyweight → weighted
• Flat ground → step edge

Add complementary exercises:

• Ankle mobility work
• Calf stretching (gentle)
• Hip strengthening (reduces compensations)
• Hamstring strengthening

Professional Treatment Options

Physical therapy:

A PT can assess biomechanics, provide manual therapy, and progress exercises appropriately. Highly recommended.

Shockwave therapy:

Some evidence for chronic cases. May stimulate healing.

Injection therapies:

PRP (platelet-rich plasma) has mixed evidence. Cortisone injections are generally avoided for Achilles (can weaken tendon).

Surgery:

Rarely needed. Reserved for cases that fail 6+ months of conservative treatment.

Prevention

Training Management

Progress gradually:

Increase weekly volume by max 10%. Less if you've had Achilles issues before.

Hill caution:

Hills load the Achilles heavily. Add gradually. Downhill is particularly stressful.

Shoe transitions:

Changing to lower-drop shoes? Transition over months, not weeks.

Recovery time:

Older runners especially need adequate recovery between hard efforts.

Calf Strength

Regular calf strengthening prevents issues:

Single leg calf raises:

• 3 sets of 15-20
• Progress to edge of step
• Build to weighted

Include bent-knee calf raises:

Targets soleus specifically. Both muscles matter.

Flexibility and Mobility

Calf stretching:

• Gastrocnemius stretch (straight leg)
• Soleus stretch (bent knee)
• Hold 30 seconds, multiple times daily

Ankle mobility:

• Ankle circles
• Knee-to-wall stretch
• Important for preventing excess tendon strain

Equipment

Shoes:

• Replace at 300-500 miles
• Adequate cushioning
• Appropriate drop height for you

If prone to Achilles issues:

• Higher drop shoes (10-12mm) reduce tendon load
• Consider heel lifts during recovery
• Avoid very flat or minimalist shoes

Return to Running

When You're Ready

Signs you can start returning:

• Minimal morning stiffness (under 1 minute)
• No pain with walking, stairs, single leg calf raises
• Eccentric exercises pain-free
• Been consistent with rehab for 4-6+ weeks

Return Protocol

Week 1:

• Walk/run 1 min run : 2 min walk
• Total 15-20 minutes
• Every other day
• Continue eccentric exercises

Week 2:

• Walk/run 2 min run : 1 min walk
• Total 20-25 minutes
• Every other day

Week 3:

• Walk/run 3 min run : 1 min walk
• Building toward continuous running

Progress if:

• No increase in symptoms during or after
• Morning stiffness not increasing
• No pain the day after

Regress if:

• Symptoms increase
• Pain during running that doesn't resolve

Maintaining Tendon Health

After returning:

• Continue calf strengthening 2-3x/week
• Regular calf stretching
• Gradual mileage progression
• Monitor for warning signs

The tendon is "remodeled" but vulnerable. Maintenance work is ongoing.

Achilles tendinopathy is one of running's most stubborn injuries—but it's treatable. The key is catching it early, loading the tendon appropriately (not just resting), and being patient with recovery. Most runners return to full activity with proper treatment. Ignore it, and you risk months or years of problems.

For more on injury prevention and recovery, see the Complete Running Injuries Guide.

Track your return to running on your dashboard.