Eccentric loading for Achilles tendinopathy--strengthening or stretching?

The prescription of eccentric loading is considered as a mainstay of non-operative rehabilitation programmes for mid-substance chronic Achilles tendinopathy. Such exercises have some degree of clinical utility in comparison with concentric training and are often referred to as a strengthening programme. Yet the dose parameters of the eccentric loading do not reflect an optimal strengthening programme and specifically avoid the normal eccentric-concentric coupling typical of the stretch shortening cycle. This manuscript identifies the arguments and counterarguments for why eccentric loading rehabilitation is not an optimal strengthening programme. It is proposed that such exercises reflect a specific stretching programme directed at the passive structures. This has two important clinical implications. Firstly, this reinterpretation of the role of eccentric exercises may direct future research into the underlying mechanisms of tendinopathy and, secondly, it may reinforce the importance of adjunct sports specific strengthening programmes.