| Specificity | |
| The tendo Achilles is loaded during the Stretch Shortening Cycle (SSC) of running and jumping. The eccentric loading regimen is specific to the SSC and optimises the SSC through strengthening the SSC response. | The Achilles tendon is fundamental to lower limb SSC performance. The potentiation of the concentric phase of the SSC is a combination of neurological potentiation and elastic recoil. The eccentric exercises as prescribed specifically avoid a concentric action following the eccentric phase, thereby intentionally negating any concentric potentiation of the SSC. This may dampen the SSC response. Furthermore, the range at which peak loading occurs during these exercises is not specific for running and jumping. |
| Force–velocity advantages | |
| The force–velocity curve clearly shows that greater loads can be achieved with eccentric loading than concentric. Therefore this explains why eccentric training has a benefit over the concentric loading regimen. | Eccentric actions generate a greater load on the musculo-tendinous unit than concentric actions at the same level of drive. There is no clear evidence that the tension in the tendon is any greater during the lowering process than an equivalent concentric action.11 The exercises have patients lower themselves from a plantar flexed position. To achieve a lowering the athlete must reduce the drive to the muscle substantially. Any increase in level of drive to the plantar flexors would actually slow the heel drop substantially and is the prime method of changing the velocity of the heel drop action. |