Plate armor permitted agility. Far from locking its wearer into a steel prison, a fitted fighting harness allowed running and kneeling because its joints followed the body's movements rather than simply enclosing them. The engineering rewarded movement. Overlapping plates, sliding rivets and shaped joint defenses gave elbows and knees room to bend while keeping vulnerable areas covered.
Weight alone misleads badly. A field harness often weighed roughly twenty to thirty kilograms, but that load was distributed across the torso and limbs instead of hanging entirely from the shoulders like a sack. Distribution did not erase effort. Mass attached to moving limbs increased rotational inertia, while the harness added to the metabolic cost of running, so mobility remained possible without becoming effortless. Fit mattered as well. Articulation worked best when the armor's moving parts aligned with the wearer's joints, preserving range of motion without requiring every plate to bend.
Strength was only admission. A knight who could bear the load still needed balance, coordination and endurance to change direction, recover footing and rise after kneeling while an opponent pressed an attack. Training therefore demanded movement. Wrestling, riding and weapons practice developed skills that lifting weight alone could not supply, although individual routines varied and specialized tournament armor could impose different restrictions from equipment intended for battle. The distinction defeats caricature. Inside a fitted harness, the body was neither free of constraint nor condemned to stiffness; the bent knee beneath the steel is the better image of its bargain.
