BFR is a means of improving sports performance and leg development, for athletes not for general fitness purposes. Hormonally Intelligent Exercise discusses positive and negative as opposing interactive modes of muscle contraction. Lifting represents positive (concentric); lowering represents negative (eccentric). Practically all sports, especially football, hockey, soccer, and basketball involve both positive and negative muscle action.

Positive = acceleration; negative = deceleration. Ask any great linebacker, and he’ll tell you that the ability to stop on a dime is no less important than fast acceleration for making plays. Furthermore, muscle pulls are at least as prevalent when attempting instantaneously to halt muscle-propelled movement as when accelerating. This makes brake force running a relatively high-risk training method – the key is, as always, gradually increasing intensity. It won’t guarantee you won’t pull a muscle when using this method, but you can control the risk more than on the playing field and it may reduce the risk of pulls during competitive play.

With BFR intensity is a function of stopping distance. When running an all-out sprint, how much space do you require to come to a complete stop? When a linebacker perceives, suddenly, that a sweep is really a reverse his legs undergo a maximal negative contraction. Until his legs stop his motion, he cannot accelerate in a different direction. For wideouts and cornerbacks, soccer and basketball players, high-intensity stop-and-go motion is paramount. BFR can by applied most easily when performing wind sprints, but also to multi-directional movement training discussed in HIE.