“Tendinitis” means active inflammation — it was the default label for chronic tendon pain for decades. But when researchers actually looked at the tissue, most long-term, overuse-related tendon pain showed something different: disorganized collagen fibers and new blood-vessel growth, with few inflammatory cells present. That breakdown process is called tendinosis, and it’s not the same thing as tendinitis.
Researchers Cook and Purdam described this as a spectrum, not a yes-or-no switch: a tendon moves between a reactive stage, a “dysrepair” stage, and a degenerative stage, depending on how it’s being loaded.[1]
The distinction matters for treatment. Rest, ice, and anti-inflammatories target inflammation — the wrong target in a degenerative tendon, where gradual loading (mechanotransduction, as used in the Alfredson protocol) is what drives repair. Calling a chronic injury “tendinitis” usually means the underlying biology hasn’t been considered — but that alone doesn’t tell you what treatment is right.