NSCA-CPT Biomechanics 5 — Questions and Answers
Question 1: When coaching a client on landing mechanics, which cue BEST reduces ACL injury risk by improving biomechanics?
- Land with knees fully extended and hips neutral
- Land stiff-legged to maximize ground contact force transfer
- Land with knees flexed, hips flexed, and soft ankles to absorb impact (Correct answer)
- Land with feet close together to narrow the base of support
Correct answer: Land with knees flexed, hips flexed, and soft ankles to absorb impact
Soft landings with hip and knee flexion distribute impact forces over time and across multiple joints, reducing peak loads on the ACL.
Question 2: Which of the following describes the force–velocity relationship in skeletal muscle?
- As concentric velocity increases, force production increases
- As concentric velocity increases, force production decreases (Correct answer)
- Force remains constant regardless of contraction velocity
- Eccentric force decreases as velocity increases
Correct answer: As concentric velocity increases, force production decreases
The force–velocity curve shows an inverse relationship during concentric contractions: faster shortening velocity results in less force due to reduced cross-bridge cycle time.
Question 3: What is the primary axis around which the forearm pronates and supinates?
- Mediolateral axis through the elbow
- Longitudinal axis through the radius and ulna (Correct answer)
- Anteroposterior axis through the wrist
- Vertical axis through the humerus
Correct answer: Longitudinal axis through the radius and ulna
Forearm rotation (pronation/supination) occurs around a longitudinal axis running from the proximal radioulnar joint to the distal radioulnar joint.
Question 4: A personal trainer notices a client's knee collapses medially during a single-leg squat. This valgus collapse is MOST likely linked to weakness in which muscle group?
- Hip adductors
- Knee extensors
- Hip abductors and external rotators (Correct answer)
- Plantar flexors
Correct answer: Hip abductors and external rotators
Weakness in the hip abductors and external rotators allows the femur to adduct and internally rotate, causing knee valgus during single-leg loading.
Question 5: Which variable in the impulse–momentum theorem directly determines the change in linear momentum?
- Power output
- Velocity alone
- The product of force and time (impulse) (Correct answer)
- The ratio of mass to acceleration
Correct answer: The product of force and time (impulse)
Impulse (F × t) equals the change in momentum (Δmv); applying a larger force or longer time duration produces a greater change in an object's momentum.
Question 6: During the concentric phase of a standing overhead press, what joint action occurs at the scapulae?
- Scapular downward rotation and retraction
- Scapular upward rotation and elevation (Correct answer)
- Scapular depression and abduction
- Scapular tilting and internal rotation only
Correct answer: Scapular upward rotation and elevation
Full shoulder flexion/abduction above 90° requires scapular upward rotation and some elevation to maintain glenohumeral congruence.
Question 7: Which of the following BEST defines 'center of mass' (COM) in human movement?
- The point at the geometric center of the body
- The point where gravitational force acts equally on all body segments
- The point at which total body mass is theoretically concentrated and gravity acts (Correct answer)
- The lowest point of the body closest to the ground
Correct answer: The point at which total body mass is theoretically concentrated and gravity acts
The center of mass is the single theoretical point representing the average location of all the body's mass, and it is the point through which gravity effectively acts.
NSCA-CPT Biomechanics 5
When coaching a client on landing mechanics, which cue BEST reduces ACL injury risk by improving biomechanics?