The Mechanical Case for Eccentrics
During an eccentric contraction, muscle fibres lengthen under load. This places greater tensile stress on the musculotendinous junction than concentric work at equivalent loads, triggering the collagen synthesis cascade through mechanotransduction pathways. The Achilles, patellar, and rotator cuff tendons — the most common clinical targets — all show measurable increases in collagen cross-link density after eight weeks of structured eccentric loading.
Three Evidence-Backed Protocols
1. Alfredson Protocol (Achilles Tendinopathy)
The original 1998 Alfredson protocol remains the benchmark for mid-portion Achilles tendinopathy. Patients perform three sets of 15 heel drops on a step — both straight-knee and bent-knee — twice daily for twelve weeks. Critically, the exercise is performed through pain; loading below the symptom threshold does not produce the same structural outcomes. Compliance rates above 80% correlate with full return to running in approximately 82% of the original cohort.
2. Decline Squat for Patellar Tendinopathy
A 25-degree decline board shifts the load curve in favour of the quadriceps-patellar unit by increasing anterior tibial inclination. Compared to flat-surface single-leg squats, decline variants produce 20–30% greater tendon stress at matched knee flexion angles. This makes them the preferred stimulus for mid-tendon patellar pathology, though they should be avoided in insertional cases where compression at end-range exacerbates symptoms.
3. Side-Lying External Rotation for Rotator Cuff
- Start position: side-lying, elbow flexed to 90°, 0.5–2 kg weight in hand
- Concentric phase: external rotation to neutral (1–2 seconds)
- Eccentric phase: slow 4-second return to internal rotation end-range
- Volume: 3 × 15 repetitions daily for 8–12 weeks
- Progression: increase load by 0.5 kg every 2 weeks if pain stays below 3/10 NRS
The pain is your guide, not your enemy — sub-symptom loading is sub-therapeutic loading.
— Alfredson & Lorentzon, 2000 (adapted)
When Eccentrics Are Not Enough
A subset of patients — particularly those with calcific tendinopathy or insertional pathology — do not respond to eccentric-only protocols. For this group, heavy slow resistance (HSR) training has demonstrated equivalent outcomes in multiple RCTs. The key variable appears to be load magnitude, not contraction type. When eccentric protocols plateau at 6–8 weeks without measurable progress, transition to HSR with a 3-second concentric, 3-second eccentric cadence and reassess at 12 weeks with the VISA-A or VISA-P outcome measure.
Comments(3)
The point about insertional vs. mid-portion distinctions is often lost in generic protocol recommendations. Clinicians really need to differentiate before prescribing the Alfredson heel drop — I've seen patients worsen significantly when compressive load isn't accounted for at the calcaneal insertion.
Great summary. One addition worth noting: the HSR vs. eccentric debate often ignores adherence data. Twice-daily Alfredson is theoretically optimal but practically abandoned by most working patients within 3 weeks. The protocol you can get your patient to follow will always outperform the one they don't.
Really helpful breakdown. Question: do you modify the eccentric cadence for older adults (65+) where the neuromuscular control piece is a bigger limiting factor? Or do you just reduce load and keep the same tempo?
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