A trainer is observing a client perform a deadlift.

For a deadlift (a hip‑hinge pattern), NASM emphasizes maintaining trunk stability via isometric contraction of the core to protect the spine. The CPT7 Study Guide states that“Stabilizers… contract isometrically to stabilize the trunk and joints as the body moves”, naming key LPHC stabilizers such as thetransversus abdominis, internal obliques, and multifidus(). Keeping aneutral spineallows these stabilizers to do their job while the hips and knees generate movement, rather than forcing the lumbar spine into excessive flexion or extension. The guide further explains the human movement system’s need to“dampen (eccentrically), stabilize (isometrically), and then accelerate (concentrically)”— NASM’sIntegrated Performance Paradigm(). In a deadlift, you eccentrically load through the hips, maintain isometric trunk stability (neutral spine), and then concentrically extend the hips and knees to stand tall. Cues like“arch your back”or“round your spine”push the lumbar segments away from neutral, compromising the length‑tension relationship of spinal tissues and shifting load to passive structures instead of the intended prime movers. By contrast,“Keep your spine neutral”aligns directly with NASM’s coaching focus on proper stabilization and joint alignment: synergists assist appropriately, stabilizers hold the trunk, and agonists at the hips extend — all while the spine remains braced and neutral for optimal safety and performance (; ).