CSC Biomechanics and Movement Analysis 1 — Questions and Answers
Question 1: What does 'center of mass' (COM) refer to in biomechanical analysis of an athlete?
- The heaviest body segment
- The point where the body's total mass can be considered to be concentrated for movement analysis (Correct answer)
- The joint around which all rotation occurs
- The muscle with the highest force output
Correct answer: The point where the body's total mass can be considered to be concentrated for movement analysis
The center of mass is the theoretical point where total body mass is concentrated; its position and movement are central to analyzing balance and stability during exercise.
Question 2: In the squat, which joint angle change most increases compressive force on the patellofemoral joint?
- Hip extension beyond neutral
- Increasing knee flexion beyond 90 degrees (Correct answer)
- Ankle dorsiflexion
- Shoulder elevation
Correct answer: Increasing knee flexion beyond 90 degrees
Patellofemoral compressive forces increase with greater knee flexion angles as the quadriceps pull becomes more mechanical disadvantaged and patella contact area shifts.
Question 3: What is the principle of 'force-velocity relationship' in muscle mechanics?
- Muscles produce the most force at the highest velocities
- As contraction velocity increases, the maximum force a muscle can produce decreases (Correct answer)
- Force and velocity are unrelated
- Eccentric contractions produce the least force
Correct answer: As contraction velocity increases, the maximum force a muscle can produce decreases
The force-velocity curve demonstrates that peak force production decreases as movement velocity increases — explaining why maximal strength and speed training require different loads.
Question 4: What is 'valgus collapse' of the knee and why is it biomechanically problematic during landing?
- Outward bowing of the knee, which is safe during sport
- Inward collapse of the knee medially, increasing ACL strain and patellofemoral stress (Correct answer)
- Hyperextension of the knee during landing
- Lateral rotation of the tibia under load
Correct answer: Inward collapse of the knee medially, increasing ACL strain and patellofemoral stress
Knee valgus collapse (medial knee displacement) during landing or squatting increases ACL and medial knee structure stress and is a major ACL injury risk factor.
Question 5: What does 'torque' mean in the context of biomechanical joint analysis?
- The linear speed of a limb
- The rotational force produced around a joint axis (force × moment arm) (Correct answer)
- The total body mass of the athlete
- The stiffness of a tendon
Correct answer: The rotational force produced around a joint axis (force × moment arm)
Torque is the product of force and its perpendicular distance (moment arm) from the axis of rotation; it determines the rotational effect of muscular forces on joints.
Question 6: In analyzing a deadlift, an excessively long moment arm at the lumbar spine most likely results from:
- Standing too close to the barbell with a vertical torso
- A horizontal back angle placing the bar far from the spine's axis of rotation (Correct answer)
- Gripping the bar too wide
- Wearing a weightlifting belt
Correct answer: A horizontal back angle placing the bar far from the spine's axis of rotation
When the back is excessively horizontal in the deadlift, the bar moves far anterior to the lumbar spine, creating a long moment arm and greatly increasing lumbar extensor torque demands.
CSC Biomechanics and Movement Analysis 1
What does 'center of mass' (COM) refer to in biomechanical analysis of an athlete?