Resistance Training Biomechanics Flashcards

During the deadlift, which lumbar spine position minimizes compressive and shear forces and is considered biomechanically safest?

Answer: Neutral lumbar spine (maintaining natural lordotic curve)

A neutral lumbar spine (natural lordotic curve with core braced) distributes compressive forces evenly across vertebral endplates and discs while minimizing posterior shear forces on spinal structures.

What is the 'double-knee bend' technique in the power clean, and why does it occur?

Answer: A natural re-flexion of the knees during the transition phase that positions the hips for the explosive second pull

The double-knee bend occurs naturally during the transition phase: after the hips rise during the first pull, the knees temporarily extend, then re-flex as the hips shift forward to position the lifter under the bar for the explosive second pull.

What is the primary biomechanical difference between the high-bar and low-bar back squat?

Answer: Low-bar squat primarily targets the quadriceps compared to the posterior chain in high-bar

In the low-bar squat, the bar rests lower on the trapezius creating a longer hip moment arm and requiring more forward torso lean (hip-dominant). The high-bar squat requires a more upright torso, greater quadriceps demand, and more ankle dorsiflexion.

At which point in the squat is knee extensor torque greatest, and why?

Answer: At or near parallel (90 degrees knee flexion) where the knee external moment arm is maximized

Knee extensor torque peaks at or near parallel because the external moment arm (perpendicular distance from knee joint center to the barbell line of force) is maximized at this depth, requiring maximum quadriceps torque to prevent further descent.

What is the NSCA-recommended bar placement and stance width for a beginner learning the back squat?

Answer: High-bar position, slightly wider than shoulder-width stance, toes angled 30-35 degrees outward

NSCA recommends high-bar placement for beginners (more upright posture, easier to learn), slightly wider than shoulder-width stance to accommodate hip anatomy, and 30-35 degree toe-out to align knees over toes and accommodate natural hip rotation.

What is 'dynamic knee valgus collapse' during landing, and why is it biomechanically dangerous?

Answer: Medial displacement of the knee during landing that simultaneously stresses the ACL and MCL, the primary non-contact ACL injury mechanism

Dynamic knee valgus (knees caving inward) during landing places the ACL and MCL under multi-directional stress — anterior tibial translation, valgus opening, and tibial internal rotation — combining to create the primary mechanism of non-contact ACL injury.