Lockout

In biomechanical terms, lockout occurs when the joint reaches full extension and the weight is supported by the bone structure rather than by active muscular contraction. This transfer of load from the muscle fibers to the skeleton creates a brief unloading moment: the muscle relaxes partially, recovers for an instant, and then the next eccentric phase begins.

In powerlifting, lockout isn't optional: without it the lift isn't approved by the judges. In bodybuilding the question is different. Many athletes deliberately avoid full lockout to maintain continuous tension on the muscle, eliminating that moment of joint unloading where the muscle rests. Not locking out completely means the fibers stay active for the entire set, increasing effective time under tension.

The choice between full lockout and continuous tension depends on the goal. If you train for strength and lifting sports, lockout is an integral part of the technical execution and needs to be practiced. If your goal is purely hypertrophic, you can experiment with sets without lockout to increase metabolic stimulus. In either case, know what you're doing and why. If you have lockout problems on heavy compound lifts, you probably have a specific weakness in the last portion of the ROM that needs to be trained with targeted accessory work.