REF-625 · Alfredson, Pietilä, Jonsson & Lorentzon, 1998 · The American Journal of Sports Medicine, · Paper · PubMed
Heavy-load eccentric calf training returned all 15 recreational athletes with chronic Achilles tendinosis to full running in 12 weeks, while 15 conventionally treated comparison patients all went to surgery
The founding loading protocol
Participants
n=30: 15 recreational athletes (12 men, 3 women; mean age 44.3 ± 7.0 years) with chronic Achilles tendinosis (degenerative changes) and a long duration of symptoms despite conventional non-surgical treatment did the eccentric programme; a comparison group of 15 recreational athletes with the same diagnosis and long symptom duration had been treated conventionally (rest, NSAIDs, shoe/orthosis changes, physiotherapy, ordinary training programmes).
Protocol
Prospective study with a conventionally treated comparison group: 15 recreational athletes (12 men and 3 women; mean age 44.3 ± 7.0 years) with chronic Achilles tendinosis and a long duration of symptoms despite conventional nonsurgical treatment did 12 weeks of heavy-load eccentric calf muscle training (from the abstract).
Comparison group: 15 recreational athletes with the same diagnosis, treated conventionally (rest, nonsteroidal anti-inflammatory drugs, changes of shoes or orthoses, physical therapy and ordinary training programs).
Measures: calf muscle strength and pain during activity (visual analog scale) before training and after 12 weeks; return to running.
Key Findings
At week 0 all patients had Achilles pain that did not allow running, and eccentric and concentric calf strength was significantly lower on the injured side.
After 12 weeks of heavy-load eccentric calf training, all 15 patients were back at their pre-injury level with full running activity; pain during activity (visual analogue scale) decreased significantly, and injured-side calf strength increased significantly to no longer differ from the uninjured side.
In the comparison group conventional treatment was unsuccessful in every case, and all were ultimately treated surgically. Authors' conclusion: a very good short-term effect in athletes in their early forties.
Protocol details (full text; not checked against the abstract): eccentric heel-drops off a step, 3 × 15 repetitions, twice daily, 7 days a week for 12 weeks, both knee-straight (gastrocnemius) and knee-bent (soleus); the concentric return is done with the uninjured leg; load progressed (backpack weight) once the exercise became pain-free.
Practical Application
In 15 recreational athletes with chronic mid-portion Achilles tendinosis, 12 weeks of heavy-load eccentric calf training restored full running in all 15 and normalised calf strength, whereas 15 conventionally treated comparison patients all ended in surgery.For clinician-confirmed chronic mid-portion Achilles pain: support the classic protocol (knee-straight and knee-bent heel-drops, twice daily, about 12 weeks; protocol details are full text), progressing load when pain-free.
It is loading, not rest — done through acceptable pain, and the athlete usually keeps some running. (Not from this paper; the base's own practice, in line with the pain-monitoring model.)
Insertional (low, at the heel) pain responds worse to full below-step drops — limit range to floor level and refer for diagnosis. (Not from this paper; the base's own practice.)
Limitations
Small (15 + 15), non-randomized, historically/conventionally treated comparison group → the effect is overstated relative to later RCTs; a very high time burden (a twice-daily protocol), which is why heavy slow resistance exists (REF-626); mid-portion only.
How this entry was checked and changed
Why this level
(small, seminal)
Content correction 2026-09-27
"All on a surgical waiting list" removed (not in the abstract); the comparison group is described as the abstract does (conventionally treated, all ultimately surgical).
Total sample corrected to n=30 (15 + 15); added age/sex from the abstract; the 3×15 / twice-daily / 180-reps protocol numbers labelled as full text (the abstract gives only "12 weeks").
Sport line normalised; "Silbernagel model" and insertional advice labelled as the base's own practice.
2026-09-28: added Protocol from the abstract (Europe PMC PMID 9617396).