Achilles Tendinopathy: An Evidence-Based Loading Framework for Clinical Practice

Achilles tendinopathy (AT) remains one of the most common and frustrating overuse injuries encountered in both athletic and general populations. Despite its prevalence, management often suffers from outdated inflammatory models, inconsistent loading strategies, or fear-based activity restriction. This article outlines a modern, evidence-based loading approach to Achilles tendinopathy, following the structure of a recent in-service presentation from a long time friend of the program, Dawson Beeler. Mr. Beeler is a hell of an orthopedic mind and decent Apex Legends player.

Epidemiology and Functional Anatomy

Achilles tendinopathy is particularly common in running populations, with prevalence estimates ranging from 6–18%. The condition most frequently affects adults aged 30–50 years and is strongly associated with training errors, such as rapid increases in volume or intensity, as well as metabolic factors including obesity, hypertension, and diabetes. Importantly, AT can significantly limit athletic participation and daily function if not managed appropriately

The Achilles tendon is formed by the confluence of the gastrocnemius and soleus, transmitting extremely high loads, up to 6–12 times body weight during running and jumping activities. A well-documented watershed zone exists approximately 2–6 cm proximal to the calcaneal insertion, an area of reduced vascularity that corresponds closely with common midportion symptoms.

Insertionally, the tendon is exposed not only to tensile load but also compressive forces against the calcaneus, which has important implications for exercise selection and joint positioning during rehab.

Pathophysiology: Moving Beyond Inflammation

Achilles tendinopathy is not primarily inflammatory. Instead, it reflects a continuum of tendon pathology characterized by:

• Collagen disorganization

• Tendon thickening

• Neovascularization

• Reduced mechanical load tolerance

This progression is commonly described using the tendon continuum model:
Reactive → Tendon Disrepair → Degenerative

As pathology advances, the tendon’s capacity to tolerate load decreases, making how and when load is applied the central clinical question.

Pain in AT is closely linked to exceeding the tendon’s current load capacity, rather than tissue damage alone. Clinically:

• Insertional AT is often aggravated by compression (e.g., deep dorsiflexion)

• Midportion AT tends to worsen with poor or inconsistent tensile loading

This distinction directly informs early exercise prescription and range-of-motion constraints.

Common Clinical Presentation

Common features include:

• Morning stiffness

• Pain with loading activities (heel raises, hopping, running)

• A “warm-up phenomenon” where symptoms ease during activity and return at greater intensity later

• Palpable tendon thickening

These hallmark signs should guide, not alarm, both clinician and patient when paired with appropriate education and load management 

Midportion AT

• Pain 2–6 cm proximal to insertion

• Typically responds well to progressive tensile loading

Insertional AT

• Pain at the calcaneal attachment

• Early avoidance of dorsiflexion beyond neutral, may drag feet

• Highly compression-sensitive

This distinction is non-negotiable when selecting exercises and progression strategies

Similar Pathologies to Keep in Mind

Key differentials to consider include:

• Partial Achilles tear

• Retrocalcaneal bursitis

• Haglund’s deformity

• Posterior ankle impingement

• Sever disease (in pediatric populations)

Accurate localization and symptom behavior remain critical to ruling these in or out.

What To Do and When: Load Progression Framework

A pain-monitoring model is recommended:

• Pain ≤5/10 during activity is acceptable

• Symptoms should not worsen the following day

• Pain and stiffness should not progressively increase week to week

Rehabilitation should follow a logical sequence:
Strength → Energy Storage → Sport-Specific Loading

Rehabilitation Progressions: Inflammatory → Maturation/Remodeling

Successful Achilles tendinopathy rehabilitation hinges on appropriate load progression, not rigid timelines. While phases are often described by weeks, progression should be criteria-based, guided by symptom response, strength capacity, and functional tolerance.

Below is a practical progression framework clinicians can use to guide decision-making from early rehab through return to sport.

Phase 1: Symptom Modulation & Load Introduction

Typical timeframe: Weeks 0–2 (variable)

Primary goals:

• Reduce pain sensitivity

• Introduce tolerable tendon load

• Educate on pain-monitoring model

• Establish movement confidence

Key interventions:

• Isometric plantarflexion holds (midrange)

• Double-leg heel raises (floor-based)

• Seated heel raises

• Gentle ankle ROM and circulation exercises

Clinical emphasis:

• Pain during exercise is acceptable up to ≤5/10

• Symptoms should not worsen the next morning

• In insertional AT, avoid dorsiflexion past neutral

Criteria to progress to Phase 2:

• Pain remains ≤5/10 during loading

• No increase in morning stiffness week to week

• Able to perform 10–15 double-leg heel raises with good control

• Improved confidence with daily activities

Phase 2: Strength Development

Typical timeframe: Weeks 2–5

Primary goals:

• Improve plantarflexion strength and endurance

• Increase tendon load tolerance

• Transition toward unilateral loading

Key interventions:

• Single-leg heel raises (floor → step as tolerated)

• Eccentric heel raises

• Introduction of tempo-controlled isotonic loading

• Begin Heavy Slow Resistance if appropriate

Clinical emphasis:

• Slow tempo (6–8 seconds per rep)

• Prioritize quality and load, not volume

• Monitor next-day symptom response closely

Criteria to progress to Phase 3:

• Able to tolerate single-leg heel raises without symptom flare

• Pain ≤5/10 during exercise and ≤5/10 the following day

• Morning stiffness stable or improving

• Demonstrates improving unilateral strength symmetry

Phase 3: Energy Storage & Elastic Loading

Typical timeframe: Weeks 6–12 (or longer as needed)

Primary goals:

• Prepare the tendon for elastic demands

• Bridge strength to dynamic function

• Restore confidence in impact activities

Key interventions:

• Quick rebounding heel raises

• Submaximal hopping and pogo jumps

• Skipping and low-level plyometrics

• Continued heavy resistance loading 2–3×/week

Clinical emphasis:

• Progress intensity before volume

• Maintain symptom-guided loading

• Ensure adequate recovery days between higher-load sessions

Criteria to progress to Phase 4:

• Pain ≤2/10 during and after plyometric tasks

• Full or near-full plantarflexion strength symmetry

• Able to tolerate repeated hopping without symptom escalation

• No delayed symptom flare the following day

Phase 4: Return to Running & Sport-Specific Loading

Typical timeframe: 3–6 months+

Primary goals:

• Restore sport-specific capacity

• Build load tolerance under fatigue

• Reduce reinjury risk

Key interventions:

• Progressive return-to-running program

• Higher-level plyometrics

• Sport-specific drills (cutting, sprinting, acceleration)

• Maintenance strength loading 2–3×/week

Clinical emphasis:

• Gradual exposure to speed and volume

• Avoid sudden spikes in weekly load

• Reinforce long-term load management strategies

Return-to-sport readiness indicators:

• Pain ≤2/10 with sport-specific tasks

• Symptom-free or minimal next-day stiffness

• Confident, symmetrical hopping and running mechanics

• Ability to tolerate training loads similar to pre-injury levels

Parting Words

Achilles tendinopathy rehab is not about eliminating pain, but about progressively expanding the tendon’s load capacity. When symptoms are monitored appropriately and load is progressed intentionally, most patients can remain active throughout rehab and return to meaningful activities and sport successfully.

References

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2. Li HY, Hua YH. Achilles Tendinopathy: Current Concepts about the Basic Science and Clinical Treatments. Biomed Res Int. 2016;2016:6492597. doi:10.1155/2016/6492597

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6. Habets B, van Cingel RE. Eccentric exercise training in chronic mid-portion Achilles tendinopathy: a systematic review on different protocols. Scand J Med Sci Sports. 2015;25(1):3-15. doi:10.1111/sms.12208

7. Cooper MT. Common Painful Foot and Ankle Conditions: A Review. JAMA. 2023;330(23):2285-2294. doi:10.1001/jama.2023.23906

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9. Reiter AJ, Martin JA, Knurr KA, Adamczyk PG, Thelen DG. Achilles Tendon Loading during Running Estimated Via Shear Wave Tensiometry: A Step Toward Wearable Kinetic Analysis. Med Sci Sports Exerc. 2024;56(6):1077-1084. doi:10.1249/MSS.0000000000003396

10. Pringels L, Capelleman R, Van den Abeele A, et al. Effectiveness of reducing tendon compression in the rehabilitation of insertional Achilles tendinopathy: a randomised clinical trial. Br J Sports Med. 2025;59(9):640-650. Published 2025 Apr 24. doi:10.1136/bjsports-2024-109138

11. Tu P. Heel Pain: Diagnosis and Management. Am Fam Physician. 2018;97(2):86-93. 

12. Silbernagel KG, Thomeé R, Eriksson BI, Karlsson J. Continued sports activity, using a pain- monitoring model, during rehabilitation in patients with Achilles tendinopathy: a randomized controlled study. Am J Sports Med. 2007;35(6):897-906. doi:10.1177/0363546506298279

13. Kakavas G, Forelli F, Korakakis V, Malliaropoulos N, Maffulli N. Neuroplastic periodization in tendinopathy. Br Med Bull. 2025;154(1):ldaf006. doi:10.1093/bmb/ldaf006

Disclaimer

We are current Doctor of Physical Therapy (DPT) students sharing information based on our formal education and independent studies. The content presented in this newsletter is intended for informational and educational purposes only and should not be considered professional medical advice. While we strive to provide accurate and up-to-date information, our knowledge is based on our current academic and clinical rotations and ongoing learning, not extensive clinical practice.