Eccentric Training for Tendinopathy: How It Works and When to Use It

Key Takeaways: Eccentric Training for Tendinopathy

Tendon rehabilitation usually takes time. Consistent loading over weeks to months is often more realistic than expecting a quick fix.
Eccentric training for tendinopathy is one of the best-studied loading strategies for Achilles and patellar tendon problems.
Tendinopathy is usually not a simple inflammation problem; it often reflects reduced tendon load tolerance and failed adaptation.
Rest and anti-inflammatory medication may calm symptoms temporarily, but long-term recovery often requires progressive loading.
Eccentric training may help through collagen synthesis, tendon remodeling, pain modulation, and changes in neovascularization.
Heavy slow resistance training can also be effective, suggesting that progressive tendon loading may matter more than the eccentric component alone.
Biomechanics, footwear, training load, sport demands, and physiotherapy assessment can all influence recovery.
Not every painful tendon is uncomplicated tendinopathy; unclear cases may require clinical assessment and sometimes imaging.

Introduction: Eccentric Training for Tendinopathy

Tendinopathy can be one of the most frustrating injuries in sport. The pain often appears during exactly the movements athletes care about most: running, jumping, accelerating, changing direction, and returning to normal training.

I know this not only as a doctor, but also from personal experience. During my own athletic career, I dealt with Achilles tendinopathy for nearly ten years. Some approaches gave temporary relief, but the method that helped me most in practice was eccentric loading.

I also see patients with similar tendon problems in clinical practice. A common pattern is that rest may calm symptoms for a while, but the pain often returns when loading increases again. From a clinical perspective, this is why tendinopathy is not just a “rest until it heals” problem. The tendon usually needs to regain its capacity to tolerate load.

This is also why stretching and eccentric training are not the same thing. Stretching may influence flexibility or short-term symptoms, but eccentric loading provides a more specific mechanical stimulus to the tendon.

In this article, I will explain why eccentric training for tendinopathy can work, what may be happening inside the tendon, when this approach is useful, and where its limitations are.

Why Eccentric Training for Tendinopathy Requires Understanding the Pathology First

Tendinopathy is not simple inflammation. Tendinopathy, a prevalent condition affecting approximately 20% of musculoskeletal complaints, arises from an imbalance between micro-injury accumulation and repair processes [1]. The pathological hallmarks — collagen disorganization, increased ground substance, and neovascularization — reflect a failed or insufficient healing response rather than classic inflammatory tissue damage.

In athletes, this failure is driven by repetitive mechanical overload. Tendinopathies are a major contributor to overuse injuries in sports [3]. The tendons most commonly involved are the Achilles, patellar, rotator cuff tendons, and lateral elbow extensor tendons, reflecting the repetitive high-load demands of running, jumping, throwing, and racquet sports [2]. Achilles tendinopathy is reported in 8–15% of runners [4], while patellar tendinopathy is highly prevalent among elite volleyball players [5].

In my clinical work, I usually see tendinopathy as a problem that has developed gradually rather than as a clear, sudden inflammatory reaction. Patients often do not describe obvious redness, heat, or swelling around the tendon. Instead, the story is usually more subtle: mild discomfort at first, then slowly increasing pain, and finally a level of symptoms that starts to interfere with training, walking, stairs, or ordinary daily activities.

This is often the point where patients come to my practice. Many have already tried resting the tendon or taking anti-inflammatory medication, but the symptoms tend to return when the tendon is loaded again. I also commonly see this background in people who run, jump, or train on hard surfaces, where the tendon is exposed to repeated mechanical stress.

Understanding what goes wrong in the tendon matters because it explains why the solution to tendinopathy involves loading — not avoiding load.

The Biology: What Happens Inside a Tendinopathic Tendon

Tendons are load-bearing structures built around Type I collagen arranged in highly organized parallel fibers. In a healthy tendon, mechanical loading activates a cellular process called mechanotransduction — tendon cells (tenocytes) sense the applied force and convert it into biochemical signals that regulate collagen synthesis and tissue remodeling [1].

Mechanotransduction pathways, mediated by integrins and focal adhesion complexes, activate signaling cascades such as MAPK/ERK and PI3K/Akt, driving tenocyte gene expression and extracellular matrix (ECM) remodeling [1]. In practical terms: appropriate load tells the tendon to rebuild and adapt. Stress shielding or reduced loading disrupts these pathways, leading to matrix disorganization and inflammation, predisposing tendons to degenerative changes [1].

In a tendinopathic tendon, this system has broken down. Collagen fibers are disorganized, there is increased ground substance, and abnormal blood vessel ingrowth (neovascularization) occurs alongside nerve fibers — a combination that is often associated with symptomatic tendinopathy. The key insight is that the tendon does not need less load to recover; it needs the right kind of load, applied progressively and systematically.

In many tendinopathy patients, the most important long-term treatment is not simply rest or medication, but a structured loading program. Eccentric training is one of the best-known examples of this approach. If the situation is very acute or painful, anti-inflammatory medication may sometimes be considered at the beginning, and this is also commonly tried in practice. However, once the initial pain situation allows it, I usually try to move the focus fairly quickly toward rehabilitation and progressive tendon loading.

This is one reason I often involve a physiotherapist early. The goal is not only to guide the exercises, but also to look at the broader mechanics behind the problem. In Achilles tendinopathy, for example, I have seen overpronation appear alongside symptoms in some patients. In other tendinopathies, the relevant factors may come from higher up the kinetic chain, such as hip, knee, or movement-control issues. A good physiotherapist can assess whether there are biomechanical factors that may be worth addressing alongside the loading program.

My own Achilles tendinopathy became noticeably less symptomatic after I started using insoles with pronation support. That personal experience does not mean the same solution applies to everyone. For many patients, the answer is not that simple. But it illustrates an important clinical point: eccentric training may be central, but the best rehabilitation plan often also considers the individual athlete’s mechanics, training load, footwear, surface, and sport-specific demands.

How Eccentric Training Works: The Proposed Mechanisms

Eccentric exercise involves controlled lengthening of a muscle-tendon unit under load. It generates higher tendon tension with lower metabolic cost, making it particularly effective for stimulating tendon remodeling while minimizing fatigue [2].

Unlike stretching, which addresses range of motion but does not stimulate the collagen remodeling required for tendon recovery, eccentric training for tendinopathy targets the underlying tissue pathology directly.

Several mechanisms have been proposed — and the evidence varies in quality across them.

1. Stimulation of Collagen Synthesis

The most direct evidence for a structural mechanism comes from a study by Langberg et al. (2007) on elite soccer players with chronic Achilles tendinosis. After 12 weeks of heavy-resistance eccentric training, collagen synthesis was increased in the initially injured tendon (PICP: pre 3.9±2.5 µg/L to post 19.7±5.4 µg/L, P<0.05) [6]. The collagen synthesis was unchanged in healthy control tendons in response to training [6]. Equally important, collagen degradation was not affected — meaning the training was driving net synthesis, not just turnover. All six injured soccer players were back playing soccer following the eccentric training regime, with VAS pain decreasing from 44±9 before to 13±9 after (P<0.05) [6].

This selective response — collagen synthesis increasing in injured tendon but not in healthy tendon — suggests that eccentric loading may preferentially target pathological tissue. Athletes who begin an eccentric protocol may also notice transiently elevated creatine kinase levels in blood tests, which reflects the expected tissue remodeling stimulus rather than pathological muscle injury.

2. Reduction of Neovascularization

A hallmark of symptomatic tendinopathy is abnormal neovascularization: ingrowth of new blood vessels (and accompanying nerves) into the tendon. Research by Ohberg and Alfredson (2004) examined 30 patients with chronic painful mid-portion Achilles tendinosis before and after 12 weeks of eccentric calf-muscle training. Before treatment, there was a local neovascularization in the area with tendon changes in all tendons. At follow-up, in 34/36 tendons with a good clinical result there was a more normal tendon structure, and in 32/36 tendons there was no remaining neovascularization. In 5/5 tendons with a poor clinical result there was a remaining neovascularization in the tendon [7].

The mechanism behind this vascular reduction is not fully understood, but the correlation with clinical outcome is striking.

3. Mechanical Load as a Pain Modulator

Eccentric exercise may also reduce tendon pain through neural mechanisms independent of structural change. A prospective microdialysis study found that while intratendinous glutamate levels were significantly higher in painful Achilles tendinosis than in normal tendons, successful treatment with eccentric training was not associated with lowered intratendinous glutamate levels despite clear reductions in pain [8]. This dissociation suggests that pain reduction can occur through pathways other than normalization of the local biochemical pain environment.

4. Mechanotransduction and Tendon Remodeling

At the cellular level, eccentric loading may enhance collagen synthesis, tendon matrix organization, and upregulation of growth factors, facilitating tendon healing [2]. The mechanical stimulus activates tenocytes and drives ECM remodeling, promoting realignment of collagen fibers along the direction of tensile forces — which is thought to enhance the mechanical properties of the tendon [9].

The honest caveat: The exact mechanism by which eccentric training for tendinopathy produces its clinical benefits remains incompletely understood. Evidence is strong that it works; the precise reasons why are still debated, and slow concentric loading may activate similar pathways.

From a practical point of view, the exact mechanism behind eccentric training may not always matter to the patient as much as the clinical outcome. If the pain improves, function returns, and the tendon tolerates load better, that is what usually matters most in daily life and sport.

Still, I usually emphasize one important point: tendinopathy is often a long-term condition. Even when symptoms improve, the tendon may remain sensitive to sudden increases in load, changes in training volume, harder surfaces, or long breaks from strengthening work. For that reason, patients may need to prepare for a longer rehabilitation process rather than expecting one quick intervention to solve everything.

Some people are fortunate. In selected cases, correcting a contributing factor such as footwear or insoles may reduce symptoms to a very low level. But in my experience, many patients still need to do the harder work: consistent, progressive loading over weeks and months. That is often the less exciting part of treatment, but it is also where much of the real recovery happens.

The Clinical Evidence for Eccentric Training for Tendinopathy

Achilles Tendinopathy

The foundational clinical evidence comes from Alfredson et al. (1998), whose protocol — heavy-load eccentric calf muscle training, 3×15 repetitions twice daily, 7 days per week for 12 weeks — remains the most widely studied eccentric training for tendinopathy intervention. VAS pain during activity decreased from 81.2 to 4.8 at 12 weeks (P<0.001) in the eccentric group, and 100% of the eccentric training group returned to their pre-injury running level at 12 weeks [12].

A 2023 systematic review and meta-analysis (Prudêncio et al., 8 RCTs) found a mean difference (MD) in pain of −1.21 (95% CI −2.72 to −0.30) in favour of eccentric exercise, identifying a significant positive effect for pain improvement in mid-portion Achilles tendinopathy [10]. The review also found that rest and wait-and-see approaches did not provide significant benefits compared to eccentric exercise [10].

Although Achilles tendinopathy is probably the tendinopathy I encounter most often in clinical practice, it is certainly not the only one. Rotator cuff tendinopathy and lateral elbow tendinopathy are also common presentations, and from time to time I see patients with patellar tendinopathy as well.

Patellar Tendinopathy

Across patellar tendinopathy studies, eccentric training for tendinopathy consistently reduced pain and improved function, with clinically meaningful VISA-P gains reported in nearly all trials, including improvements from approximately 30–55 to 70–90 points within 12–24 weeks [2]. When compared directly with concentric training, eccentric training was superior, as concentric training showed minimal improvement and poor tolerance [2].

Patellar tendinopathy is another condition I see from time to time, especially in athletes whose sport involves repeated jumping. In practice, this often means basketball players, volleyball players, or athletes in other jumping and landing sports. This is also why patellar tendinopathy is commonly called “jumper’s knee” in clinical language, including in Finland.

Eccentric vs. Heavy Slow Resistance (HSR)

An important finding from recent trials is that heavy slow resistance (HSR) training — which combines concentric and eccentric phases — produces outcomes comparable to isolated eccentric training. In Beyer et al. (2015), both ECC and HSR showed significant (P < .0001) improvements in VISA-A and VAS from 0 to 12 weeks, and these improvements were maintained at the 52-week follow-up. Concomitant with the clinical improvement, there was a significant reduction in tendon thickness and neovascularization. None of these clinical and structural improvements differed between the ECC and HSR groups [11]. Patient satisfaction tended to be greater after 12 weeks with HSR (100%) than with ECC (80%; P = .052) [11].

The emerging consensus: eccentric training for tendinopathy works, but it is not uniquely superior to other well-dosed loading strategies. The critical variable is load — sufficient mechanical stimulus applied progressively.

In everyday clinical practice, eccentric training still often feels like the “gold standard” approach for tendinopathy rehabilitation. Part of this may simply be that clinicians and physiotherapists have more experience with it, and many traditional tendon protocols have been built around eccentric loading.

Heavy slow resistance training is also relevant, and some physiotherapists use it successfully. In practice, however, I see it used less often than eccentric-only programs. From my perspective, the key point is not to treat eccentric exercise as a magic method, but to understand the broader principle behind it: the tendon needs a structured, progressive loading stimulus. Eccentric training is one well-established way to provide that stimulus, while heavy slow resistance may be another useful option when it fits the patient, the physiotherapist’s approach, and the training context.

The Alfredson Protocol and Its Variants

The Alfredson protocol for Achilles tendinopathy remains the most widely replicated eccentric training for tendinopathy protocol [12]:

Straight-knee heel drops (3×15 repetitions) — targeting the gastrocnemius Bent-knee heel drops (3×15 repetitions) — targeting the soleus Performed twice daily, 7 days per week, for 12 weeks Load progressed by adding backpack weight when pain allows Exercise is performed into pain — if pain is absent, load is increased

For patellar tendinopathy, the standard eccentric training for tendinopathy protocol uses single-leg decline squats on a 25° board, 3×15 repetitions, twice daily.

Pain monitoring is an integral feature of eccentric protocols. Most protocols allow exercise into moderate discomfort (VAS 4–5/10) as part of progression [2]. This is a key distinction from many rehabilitation approaches: eccentric training for tendinopathy is not pain-free by design.

In my experience, many physiotherapist colleagues in Finland still use the Alfredson protocol widely when treating Achilles tendinopathy, and similar eccentric-loading protocols are used for other tendinopathies as well. This probably reflects both the long history of eccentric training in tendon rehabilitation and the fact that the protocol is relatively simple to teach, monitor, and progress.

The Honest Limits of Eccentric Training for Tendinopathy

Eccentric training for tendinopathy is the best-supported conservative treatment, but it is not a universal solution:

Some patients do not respond adequately to eccentric protocols alone and may require adjunct interventions (such as sports massage for short-term symptom relief) or a progression to HSR
Structural changes in the tendon (e.g., large intratendinous tears, calcification) may not resolve with loading
Very chronic or severely degenerated tendons may require adjunct interventions (ESWT, HSR, PRP) or surgical consultation
The mechanism of benefit is not fully understood — slow concentric loading appears to produce similar outcomes in many studies, suggesting that load magnitude and progressive dosing may matter more than the eccentric component specifically

A careful history is still essential. Not every painful tendon should automatically be treated as uncomplicated tendinopathy. In some cases, it is important to consider whether there has been a partial tear, a more significant traumatic injury, or another pathology that would change the treatment approach.

For that reason, when the clinical picture is unclear or the symptoms suggest a possible structural injury, I may refer the patient for an ultrasound examination to assess the tendon and exclude other relevant pathology. If the findings are consistent with tendinopathy rather than a tear or another condition requiring a different approach, eccentric loading often becomes one of the central components of rehabilitation.

Conclusion: Eccentric Training for Tendinopathy

Eccentric training remains one of the most extensively studied and clinically useful rehabilitation strategies for tendinopathy. The evidence suggests that it can reduce pain, improve function, and stimulate favorable tendon adaptations, even though the exact mechanisms responsible for these benefits are not yet fully understood.

From my own perspective, both as a doctor and as someone who struggled with Achilles tendinopathy for nearly a decade during my athletic career, the practical importance of eccentric loading is difficult to ignore. While the scientific explanations are fascinating, patients are usually interested in a simpler question: does it help them return to training and daily activities with less pain? In many cases, the answer appears to be yes.

At the same time, tendinopathy is rarely solved by a single exercise protocol alone. Successful rehabilitation often requires attention to training load, biomechanics, footwear, recovery, and individual risk factors. Eccentric loading may be a central component of treatment, but it is usually most effective when viewed as part of a broader rehabilitation strategy rather than a standalone cure.

Perhaps the most important lesson is that tendinopathy is generally a problem that responds to appropriate loading rather than complete avoidance of loading. While rest may temporarily reduce symptoms, long-term improvement often requires the tendon to gradually regain its capacity to tolerate mechanical stress. For many athletes, that process demands patience, consistency, and months rather than days.

The encouraging news is that tendons are living tissues capable of adaptation. When loading is applied progressively and intelligently, meaningful improvement is often possible—even in cases that have persisted for a long time.

References

[1] https://doi.org/10.33594/000000743

[2] https://doi.org/10.52082/jssm.2026.34

[3] https://pubmed.ncbi.nlm.nih.gov/31827363/

[4] https://doi.org/10.1186/1757-1146-4-15

[5] https://doi.org/10.1177/03635465030310031401

[6] https://doi.org/10.1111/j.1600-0838.2006.00522.x

[7] https://pubmed.ncbi.nlm.nih.gov/15060761/

[8] https://doi.org/10.1007/s00167-003-0360-0

[9] https://doi.org/10.3389/fbioe.2025.1560025

[10] https://doi.org/10.1186/s13102-023-00618-2

[11] https://pubmed.ncbi.nlm.nih.gov/26018970/

[12] https://journals.sagepub.com/doi/10.1177/03635465980260030301