The Alfredson protocol is a 12-week exercise program for chronic Achilles tendinosis — two calf exercises, done with the knee straight and bent, loaded to the point of provoking some pain, several sets a day, without surgery.
In the original study, researchers found that all 15 recreational athletes with long-standing Achilles pain who completed the program returned to running at their pre-injury level.[1] That result was striking enough to reshape how tendon injuries are treated more broadly.
It’s still the benchmark other tendon-loading programs are measured against. But the original evidence is a small study — 15 patients, not a large randomized trial — and success there doesn’t mean every tendon responds the same way. Tendinosis at the very bottom of the Achilles, or inside the watershed zone, often needs a different loading angle to avoid irritating the bone.