CSCS: Biomechanics of Resistance Flashcards

An athlete performs a bench press with a wide versus narrow grip. The wide grip primarily changes which biomechanical variable?

Answer: Moment arm at the shoulder joint

A wider grip reduces the horizontal distance the bar travels and alters the shoulder moment arm, shifting emphasis toward the pectorals over the triceps.

The coefficient of static friction between an athlete's shoe and the floor is 0.8, and the athlete weighs 800 N. What is the maximum horizontal force the athlete can exert without sliding?

Answer: 640 N

Maximum static friction = μs × Normal force = 0.8 × 800 N = 640 N.

Which type of muscle contraction produces the greatest peak force at a given velocity?

Answer: Eccentric

Eccentric contractions can generate 20–50% more force than isometric contractions because cross-bridges are forcibly stretched, allowing greater tension per bridge.

What is the primary reason the deadlift generates higher lumbar compressive forces compared to many other resistance exercises?

Answer: The load is held far from the body's center of mass, increasing the spinal moment arm

When the barbell is positioned anterior to the spine, its large moment arm relative to the lumbar joints requires enormous erector spinae forces to maintain posture, increasing compressive load.

During a sprint start, an athlete pushes backward and downward against the blocks. According to Newton's third law, the resulting ground reaction force is directed:

Answer: Forward and upward on the athlete

Newton's third law states that the reaction force is equal in magnitude and opposite in direction; pushing backward-downward produces a forward-upward ground reaction force on the athlete.

Which of the following best explains why Bulgarian split squats produce high hip flexor (iliopsoas) eccentric demand on the rear leg?

Answer: The rear leg's hip is in an extended and internally rotated position, elongating the iliopsoas

With the rear foot elevated, the hip is driven into extension and slight internal rotation, placing the iliopsoas on maximal stretch and creating a large eccentric demand.

When analyzing projectile motion of a thrown medicine ball, ignoring air resistance, the horizontal component of velocity:

Answer: Remains constant throughout the flight

In projectile motion without air resistance, there is no horizontal force, so horizontal velocity remains constant by Newton's first law.