Do you think overloading a muscle throughout its range of motion (ROM) best optimises muscle growth? Well there is some truth to the statement, however, some parts of the ROM are more important than others. Overloading the muscle at stretched or long muscle lengths (LML) optimises muscle growth. It can also really help if you can overload a muscle where it is strongest.
So let’s look at the latter here in terms of a strength curve approach, more specifically an ascending strength curve (see figure). These are exercises where the beginning part of the movement (long muscle length – LML) is hard and end ROM is easier (short muscle length - SML) e.g. squat and bench press. In these exercises you can lift more in the last quarter of a movement (partials), however, you are limited by muscle force capability in the first quarter of the concentric contraction.
EBR overcomes this limitation of free weight resistance by progressively increasing resistance throughout the concentric ROM i.e. EBR is less at LML or where the muscle is weak, and more at SML where the muscle is strong (see diagram). EBR in short allows the force-ROM curve to be modified for an exercise, and likely explains many of the performance benefits reported in the research.