If movement is the product of unbalanced forces across a joint, what does that mean for traditional agonist-antagonist strength ratios? Dr. Lon Kilgore believes training to conform to hypothetical ratios is impractical and will not result in greater functional fitness.
In most instances during exercise we want to create an unbalanced force across a joint or joints in order to create movement. But when we consider joint integrity during movement, it is often proposed that we need to balance forces across the joint in order to stabilize it. But how do we manage to produce an unbalanced force driving movement and then balance force across a joint?
A balanced force across a joint is not the same as “strength balance” between agonists and antagonists. A precisely balanced force across a single joint would result in an isometric muscle action and produce no movement. Antagonist muscles are not recruited extensively or are inhibited in force production in order to allow the agonist to drive movement.
This renders the 1:1 (or 2:3 or 3:1, etc.) concept of strength balance irrelevant during movement. This does not mean that an antagonist muscle may not be active during agonist contraction. Antagonists are important, but the notion that we can magically determine how strong the multitude of agonist and antagonist muscles need to be is not practical.
A one-size-fits-all statement about optimal strength balance is not possible. It is our charge to develop our trainees to be fully functional, able to both tolerate and produce a complete spectrum of real forces. We need not minimize the forces presented during training or tune force-generation capacity to a hypothetical ratio. The best advice is to strengthen all relevant axes of movement around a joint.