Force-Velocity, Joint Position and the Minimum Effective Loading Dose

The force velocity curve shows eccentric contractions produce about 50% more force than a maximal isometric, and isometrics produce more than any concentric effort. Eccentric and isometric loading are therefore the best tools for straining the tendon, and they form the basis of Peter's adaptation framework. A 2022 study by McMahon equalized internal patellar tendon forces across two arcs of movement and found more adaptation in the 40 to 90 degree arc, where the tendon is under more pre-stretch. Position matters as much as load. For the Achilles, Peter works through approximate internal forces: in 10 degrees of dorsiflexion a strong isometric push can produce around 2,700 newtons, roughly 3.7 times body weight, and internal force falls as the ankle moves into plantar flexion. On dosage, a study comparing five and 2.5 isometric sessions per week found no difference in stiffness gains, and lower weekly loading volume trended toward better results. Two to three sessions a week may be enough, and doing too much risks tendon fatigue.