Origins of the 'Alfredson eccentric heel drop protocol' for achilles tendon pain. (It's a good story
Back in the mid 1990's Dr. Alfredson had chronic achilles tendon pain himself and after failed conservative care asked his boss to book him in for surgery. His boss refused because he thought the case wasn't serious enough and the clinic couldn't afford to have him off on sick leave. Frustrated with the ongoing pain, Dr. Alfredson decided to load his achilles aggressively to the point of needing immediate surgical repair. As you may have guessed, the loading strategy he took was eccentric heel drops off the back of a step. To his surprise, his achilles tendinopathy didn't worsen but in fact completely resolved. The 'Alfredson eccentric heel drop protocol' was born. Since then, there have been variations of the protocol developed for for different types of achilles pathology (e.g mid-portion vs. insertional tendinopathies).
Hakan Alfredson is still one of the global leaders in achilles and patella tendon research.
Some research suggests the mechanism behind the effectiveness of the eccentric heel drop is the 'eccentric' (lowering) component of the exercise which creates a fundamental rearrangement of the tendons structure, creating a stronger tendon with a higher proportion of type 1 collagen (the good stuff!).