CSCS Resistance Training Biomechanics 5 — Questions and Answers
Question 1: A muscle with a high physiological cross-sectional area (PCSA) is best suited for:
- Producing large ranges of joint motion
- Generating high force output (Correct answer)
- Producing rapid shortening velocity
- Improving joint flexibility
Correct answer: Generating high force output
PCSA is directly proportional to maximal force-producing capacity; muscles with greater PCSA can generate more force regardless of fiber length or pennation.
Question 2: Which of the following best describes 'valgus collapse' at the knee during a squat and its biomechanical implication?
- The knee moves laterally, increasing IT-band tension and reducing ACL stress
- The knee caves medially, increasing valgus torque and stress on the medial knee structures and ACL (Correct answer)
- The knee hyperextends, reducing quadriceps demand
- The knee flexes beyond 90°, increasing patellofemoral compressive forces only
Correct answer: The knee caves medially, increasing valgus torque and stress on the medial knee structures and ACL
Knee valgus collapse (medial knee displacement) increases frontal-plane valgus torque, placing harmful stress on the ACL, MCL, and medial compartment of the knee.
Question 3: Which variable most directly determines the mechanical work performed during a resistance exercise set?
- Time under tension
- Force applied multiplied by the displacement of the load (Correct answer)
- Heart rate response during the set
- The number of motor units recruited
Correct answer: Force applied multiplied by the displacement of the load
Mechanical work equals force multiplied by displacement (W = F × d); in lifting, this reflects the load moved and the distance it travels.
Question 4: In a Romanian deadlift (RDL), compared to a conventional deadlift, the hamstrings experience greater mechanical stimulus primarily because:
- The RDL uses a shorter range of motion at the knee
- The hip hinge in the RDL creates a larger moment arm for the hamstrings and allows greater hip flexion under load (Correct answer)
- The RDL eliminates gluteus maximus involvement
- The RDL requires greater knee flexion, stretching the hamstrings distally
Correct answer: The hip hinge in the RDL creates a larger moment arm for the hamstrings and allows greater hip flexion under load
The RDL maintains minimal knee bend and emphasizes hip hinging, placing the hamstrings under a large moment arm and stretching them under significant load.
Question 5: Which principle explains why an athlete can generate more force at the beginning of a concentric contraction after a brief pause (vs. from a static start with no stretch)?
- Principle of specificity
- Length-tension relationship only
- Post-activation potentiation (PAP)
- Stretch reflex and elastic energy utilization from the SSC (Correct answer)
Correct answer: Stretch reflex and elastic energy utilization from the SSC
A controlled eccentric pre-stretch activates the stretch-shortening cycle, utilizing stored elastic energy in tendons and the myotatic reflex to boost subsequent concentric force.
Question 6: When performing a lat pulldown with a wide overhand grip, the primary axis of motion is at the:
- Wrist joint
- Elbow joint
- Shoulder joint (Correct answer)
- Scapulothoracic joint
Correct answer: Shoulder joint
The primary pulling motion in a lat pulldown is shoulder adduction (and extension), with the shoulder joint as the main axis of rotation.
Question 7: The concept of 'joint reaction force' in biomechanics refers to:
- The voluntary force produced by muscles crossing a joint
- The compressive and shear forces acting on joint surfaces as a result of muscle forces and external loads (Correct answer)
- The elastic recoil force generated by ligaments
- The ground reaction force transmitted through the kinetic chain to a joint
Correct answer: The compressive and shear forces acting on joint surfaces as a result of muscle forces and external loads
Joint reaction forces are the net compressive and shear forces at articular surfaces resulting from the combined effects of muscle contractions, body weight, and external loads.
CSCS Resistance Training Biomechanics 5
A muscle with a high physiological cross-sectional area (PCSA) is best suited for: