Achilles Tendinopathy: Eccentric Protocol & Running

Understanding Achilles Tendinopathy in Runners

Achilles tendinopathy is one of the most common running injuries, presenting as pain, stiffness, and localized swelling in the Achilles tendon. The underlying pathology involves micro-tearing and degeneration of the tendon's collagen matrix. In runners, it is typically caused by rapid increases in training mileage, excessive hill running, or poor calf muscle capacity.

Successful recovery relies on a structured program of physiotherapy and sports rehabilitation. Passive treatments like ice, rest, and orthotics may manage temporary discomfort, but targeted progressive tendon loading is the only intervention that restores the tendon's structural integrity and load tolerance.

Mid-Portion vs. Insertional Achilles Tendinopathy

Before starting rehabilitation, a clinician must determine if the injury is mid-portion or insertional, as the loading exercises are performed differently:

• Mid-Portion Tendinopathy: Pain is localized 2 to 6 cm above the heel bone. Exercises are performed off the edge of a step, allowing the heel to drop below the level of the forefoot (full range of motion).
• Insertional Tendinopathy: Pain is localized directly at the attachment site on the heel bone (calcaneus). Performing heel drops off a step compresses the tendon against the calcaneal bone, worsening symptoms. Therefore, insertional tendinopathy exercises must be performed on flat ground.

The Alfredson Eccentric Protocol

The Alfredson protocol is a highly researched, evidence-based eccentric training program for chronic Achilles tendinopathy. It targets the calf complex (gastrocnemius and soleus muscles) and the tendon itself, promoting collagen remodeling and increasing tendon stiffness.

The Exercises

1. Gastrocnemius Eccentric Heel Drop (Straight Knee): Stand on the edge of a step with your heels hanging off. Lift up onto your toes using both feet. Lift the uninjured foot, and slowly lower yourself down on the injured foot until your heel is slightly below the step. Return to the starting position using only your uninjured leg.
2. Soleus Eccentric Heel Drop (Bent Knee): Perform the exact same movement, but keep the knee of the loaded leg bent to approximately 30 degrees during the descent. Bending the knee relaxes the gastrocnemius and isolates the deep soleus muscle.

Protocol Parameters

• Frequency: 3 sets of 15 repetitions of both variations, performed twice daily (totaling 180 repetitions per day).
• Duration: Consistent daily performance for 12 weeks.
• Pain Guide: Moderate pain during the exercise (up to 3-4/10) is normal and acceptable. Once the exercises become pain-free, add weight (using a backpack filled with books or holding a dumbbell) to continue stimulating tendon remodeling.

Running Modifications and the Pain Monitoring Model

Complete rest is rarely recommended for runners with Achilles tendinopathy. Instead, physical therapists use a "Pain Monitoring Model" to allow continued running while the tendon recovers. Under this model, running is permitted if the following criteria are met:

• During Activity: Pain must remain at or below a 3 out of 10 on a visual analog pain scale.
• After Activity: Any increase in pain must settle back to baseline within 24 hours.
• Morning Stiffness: There should be no increase in pain or stiffness in the Achilles tendon the morning after a run.

If these criteria are met, running is considered safe. If pain spikes or morning stiffness increases, training volume or intensity must be reduced.

Comparison Table: Mid-Portion vs. Insertional Rehab Protocols

| Attribute | Mid-Portion Achilles Tendinopathy | Insertional Achilles Tendinopathy | | :--- | :--- | :--- | | Pain Location | 2 to 6 cm above the heel attachment | Directly on the calcaneus (heel bone) | | Exercise Surface | Off the edge of a step (eccentric heel drops) | Flat ground only (no heel drops below horizontal) | | Biomechanical Rationale | Full excursion stretches and strengthens tendon | Avoids calcaneal impingement/compression at attachment | | Ancillary Modalities | Foam rolling, shockwave therapy, eccentric loading | Heel lifts in shoes, shockwave therapy, isometric holds | | Target Running Surface | Flat asphalt or track (avoid steep hills) | Flat surfaces (avoid hills and soft sand) |

Comprehensive Calf and Ankle Biomechanics

While eccentric exercises are the foundation of treatment, a comprehensive program must address other biomechanical factors. Weakness in the gluteal muscles and poor ankle dorsiflexion mobility can alter gait mechanics, placing excessive strain on the Achilles tendon. Targeted hip strengthening and ankle mobility drills help distribute force evenly throughout the lower extremity during the running cycle. For patients with high pain levels, clinical pain management modalities, such as manual therapy and shockwave treatment, can be integrated to facilitate compliance with loading exercises.