What eccentric loading protocols involve
Eccentric loading emphasizes the lengthening phase of a contraction under load. The best-known example is the Alfredson protocol for Achilles tendinopathy, which prescribes heel-drop exercises performed slowly, in high daily volume, over a programme of around 12 weeks. The hallmark is that the muscle-tendon unit is loaded as it lengthens, and the work is progressed by adding external weight as tolerance improves.
These protocols are typically used for chronic mid-portion tendinopathy and are applied to other tendons such as the patellar tendon with adapted exercises.
Why slow eccentrics may help tendons
The proposed effect is that controlled, progressive load stimulates tendon cells to remodel the collagen matrix, alongside changes in pain processing and load tolerance. Across the evidence, structured eccentric programmes are associated with reduced pain and improved function in many people with chronic tendinopathy, though responses vary and some discomfort during the exercise is expected and usually permitted.
Tendinopathy management is individual and other loading styles can be comparably effective. This is general educational information, not medical advice; a qualified clinician should confirm the diagnosis and set the appropriate protocol and progression.