Updated May 2026. Written by the Upwell Health Collective clinical team. Clinically reviewed May 2026. Next review due November 2026. For educational purposes only.
Here is the conversation that happens in clinics across Australia every week. A runner comes in with Achilles pain. They’ve been resting for 6 weeks on the advice of their GP. The pain has settled. They’re ready to run. They go for their first run back. Two kilometres in, the Achilles fires up again. They come back to the clinic confused and frustrated. “I rested. Why is it back?”
Because rest is not the treatment for Achilles tendinopathy. Rest is the management of symptoms in the short term. The treatment — the actual biological intervention that changes what is happening in the tendon — is progressive mechanical loading. And a tendon that has been rested for 6 weeks, then immediately subjected to running load without a structured return, is a tendon that has been perfectly prepared for a flare-up.
Achilles tendinopathy is one of the most common overuse injuries in runners, triathletes, and endurance athletes. It is also one of the most mismanaged. The combination of persistent rest, passive treatments, and inadequate loading programmes keeps runners in a pain-and-rest cycle for months — sometimes years — when the evidence-based answer is to load the tendon progressively from the beginning.
This article explains what Achilles tendinopathy actually is, why the tendon responds to load rather than rest, what the current evidence says about treatment, and how to build a programme that gets runners back to training properly.
The Achilles tendon is the largest and strongest tendon in the body. It connects the calf muscles — the gastrocnemius and soleus — to the heel bone (calcaneus) and is responsible for the powerful plantarflexion that propels the foot off the ground with every step of every run. In an average kilometre of running, the Achilles tendon may absorb and return forces equivalent to 6 to 8 times body weight thousands of times.
Achilles tendinopathy is not tendon inflammation in the classical sense. Despite the historical term “tendinitis,” the pathological process in established Achilles tendinopathy is not primarily inflammatory. It is a failed healing response — a degenerative change in the tendon’s internal structure, characterised by disruption of the normally parallel collagen architecture, increased ground substance, failed vascular ingrowth, and in some cases, partial degenerative tearing.
This distinction matters because it changes the treatment logic entirely. Inflammation is managed with rest and anti-inflammatories. Tendinopathy is treated with mechanical loading — because the tendon’s mechanotransduction pathway (the mechanism by which it converts mechanical signals into biological adaptation) is the primary driver of tendon remodelling. You cannot heal a tendon by avoiding the stimulus it needs to remodel.
There are two main presentations of Achilles tendinopathy:
Achilles tendinopathy is fundamentally a load management failure. The tendon has been asked to adapt faster than it can. The most common triggers are:
The Achilles tendon responds to mechanical load through a process called mechanotransduction: tenocytes (tendon cells) detect mechanical strain and respond by producing collagen, modulating matrix metalloproteinases, and initiating remodelling of the tendon’s internal architecture. Without sufficient mechanical stimulus, this remodelling process stalls and the tendon remains in its degenerative state.
Heavy mechanical loading — specifically, slow, progressive, high-load calf exercise — provides the stimulus that drives tendon remodelling. A randomised crossover trial (Pringels et al., Med Sci Sports Exerc, 2025) confirmed that loading speed and intensity in calf training impact acute changes in Achilles tendon thickness and stiffness, with implications for how progressive loading should be structured. The fundamental mechanism: controlled mechanical strain stimulates collagen synthesis and promotes the structural remodelling that restores tendon function.
This is why the evidence for Achilles tendinopathy treatment is so consistent in pointing toward exercise. The 2024 AOPT/APTA Clinical Practice Guideline (third revision) — the most comprehensive and current evidence-based guidance for Achilles tendinopathy management — states explicitly: “Clinicians should use mechanical loading, which can be eccentric, concentric, isometric, isotonic, and plyometric use of the plantar flexors.” Exercise improved function by 20 points on the VISA-A (95% CI: 11 to 30) more than a wait-and-see approach, across 13 RCTs included in the most recent network meta-analysis.
The Alfredson eccentric protocol was the landmark intervention that shifted Achilles tendinopathy management toward loading. First published in 1998, it involves eccentric-only heel drops performed on a step (through the full range, allowing the heel to drop below step level), progressing to weighted eccentric work, performed twice daily for 12 weeks.
Success rates of 60 to 80% were reported in the original work and confirmed in subsequent studies. The protocol works because eccentric loading places the tendon under significant tensile strain during the lengthening phase, providing the mechanical stimulus needed for remodelling.
Limitations: the eccentric-only approach is painful in the early stages, requires strict twice-daily compliance, and is not suitable for insertional tendinopathy (where heel-drop range provokes compression at the insertion).
The Heavy Slow Resistance protocol (Beyer et al., JOSPT, 2015) uses slow, high-load bilateral and unilateral calf raises through the full range, performed three times per week for 12 weeks. The “slow” component (6-second repetitions) maximises time under tension and tendon strain. Load progresses from 15RM to 6RM over 12 weeks.
The pivotal RCT comparing eccentric-only and HSR found both produced equally positive clinical results at 12 weeks and 1-year follow-up, with HSR associated with greater patient satisfaction. A 2023 systematic review and meta-analysis found eccentric exercise more effective than other exercise types for midportion Achilles tendinopathy, but subsequent network meta-analyses found that multiple loading modalities — eccentric, concentric, and isotonic combined — produced equivalent outcomes.
The 2024 CPG concludes: exercise frequency, total sessions, and care duration did not significantly influence clinical outcomes across the included RCTs. What matters most is that the tendon is progressively loaded with sufficient intensity, regardless of the specific protocol used.
Isometric calf contractions — held for 30 to 45 seconds at 70 to 80% of maximum voluntary contraction, performed 4 to 5 times per set — have emerged as a valuable early-phase Achilles loading tool, particularly during periods when isotonic loading is too painful to perform. The evidence for isometric loading as an immediate analgesic in tendinopathy was established in patellar tendinopathy research (van Ark et al., 2016) and has been extended to Achilles presentations.
Isometric loading is particularly useful in the reactive phase (early flare-up with a hot, swollen, painful tendon) where the goal is to provide a mechanical stimulus without the tissue strain of through-range loading. It is a bridge, not an endpoint.
Silbernagel’s combined eccentric-concentric approach allows athletes to continue training during Achilles rehabilitation — a significant advantage over complete rest protocols. It uses pain-monitoring guidelines (allowing pain up to 5/10 during exercise, settling within 24 hours) to guide loading decisions, and integrates isometric, isotonic, and plyometric loading in a progressive framework.
The evidence for symptom-guided loading — staying active while monitoring pain response — is strong and aligns with the current CPG recommendations. An international Delphi consensus on Achilles tendinopathy exercise parameters (BJSM, 2025) found expert consensus on progressive loading as the cornerstone of management, with symptom-guided progression as the preferred monitoring tool.
Understanding what the evidence does not support is as important as understanding what it does.
Rest: As established above, rest manages pain in the short term. It does not treat the underlying tendinopathy. A tendon rested for 6 weeks and then returned to full running load will flare within days. Rest without concurrent loading is not a rehabilitation strategy. It is a delay.
Passive stretching: Stretching the Achilles tendon — particularly aggressive dorsiflexion stretching — is contraindicated in the acute and reactive phases of tendinopathy. Stretching adds compression and tensile stress to an already irritated tendon. For insertional tendinopathy specifically, dorsiflexion stretching directly compresses the tendon at its insertion and will provoke a flare. Calf muscle length should be maintained through range-of-motion work, not aggressive stretch.
Anti-inflammatory medications alone: NSAIDs provide short-term symptom relief and may be appropriate for acute pain management. They do not modify the underlying degenerative process and should not be used as a substitute for the loading programme that treats it.
Corticosteroid injections: Cortisone injections have been consistently associated with short-term symptom relief followed by worse medium-term outcomes in Achilles tendinopathy. The 2024 CPG notes that cortisone is associated with increased risk of tendon rupture and cannot be recommended as a primary treatment. If a patient has had cortisone into the Achilles, the loading programme must be approached with additional caution regarding rupture risk.
Foam rolling and massage as standalone: Soft tissue work to the calf and Achilles can be a useful adjunct for pain management and symptom control. It does not treat the tendinopathy. It is a symptomatic tool, not a structural one.
For runners managing Achilles tendinopathy, the return-to-running framework should follow a structured progression that prevents the boom-and-bust cycle of symptomatic rest and premature return.
The key clinical decision points:
Insertional Achilles tendinopathy requires specific modifications from the midportion protocol because of the additional compression component at the tendon’s insertion point.
Key differences in insertional management:
When an Achilles tendinopathy presentation comes through Upwell’s doors, the assessment covers:
Most runners with midportion Achilles tendinopathy who engage fully with a structured loading programme are back running within 12 weeks. The timeline for insertional presentations is sometimes longer. The critical variable in every case is compliance with the loading programme — not the passive treatments surrounding it.
If your Achilles has been symptomatic for more than 4 to 6 weeks and has not responded to rest, contact our team or book an assessment. You need a loading programme, not more rest.
Achilles tendinopathy is not an inflammatory condition. It is a failed tendon healing response driven by load exceeding the tendon’s capacity to adapt. The treatment is progressive mechanical loading — not rest, not passive treatment, and not stretching.
The evidence hierarchy is clear: heavy slow resistance training and Alfredson eccentric protocols produce equivalent positive outcomes. Isometric loading is useful in the reactive phase. Symptom-guided return to running is safe and preferable to enforced rest. Cortisone should be avoided. Passive treatments are adjuncts, not treatments.
Every runner who has rested for weeks and found their Achilles flares the moment they return to running has learned the hard way what the research has been saying for two decades: the tendon cannot be healed by avoiding the load it needs to remodel. The answer is structured, progressive, supervised loading — and it works.
This article is for educational purposes only. It does not substitute for individual clinical assessment. Information last reviewed May 2026.