CSCS CSCS: Biomechanics of Resistance 2 — Questions and Answers
Question 1: What is the mechanical advantage of a muscle-joint system when the moment arm of the muscle force is shorter than the moment arm of the external load?
- Greater than 1.0
- Less than 1.0 (Correct answer)
- Equal to 1.0
- Indeterminate without mass data
Correct answer: Less than 1.0
Mechanical advantage equals the ratio of the effort moment arm to the load moment arm; when the muscle arm is shorter, this ratio is less than 1.
Question 2: During a barbell back squat, which joint experiences the greatest compressive patellofemoral force at approximately 90° of knee flexion?
- Hip joint
- Lumbar spine
- Patellofemoral joint (Correct answer)
- Ankle mortise
Correct answer: Patellofemoral joint
Patellofemoral compressive force peaks near 90° of knee flexion because quadriceps tension and knee contact area interact to maximize joint reaction force.
Question 3: The stretch-shortening cycle (SSC) enhances force production primarily because of energy stored in which tissue?
- Myosin heavy chains
- Actin filaments
- Elastic connective tissue (tendons and fascia) (Correct answer)
- Sarcoplasmic reticulum
Correct answer: Elastic connective tissue (tendons and fascia)
During the eccentric phase, elastic energy is stored in tendons and fascia and subsequently released during the concentric phase to augment muscular force.
Question 4: If an athlete increases the velocity of a concentric muscle contraction, what generally happens to the force the muscle can produce?
- Force increases proportionally
- Force remains constant
- Force decreases (Correct answer)
- Force first increases then decreases
Correct answer: Force decreases
According to the force–velocity relationship, concentric force output decreases as contraction velocity increases due to reduced cross-bridge cycling time.
Question 5: Which term describes the rotational effect produced by a force acting at a perpendicular distance from an axis of rotation?
- Impulse
- Work
- Torque (Correct answer)
- Power
Correct answer: Torque
Torque (moment of force) is defined as the product of force magnitude and its perpendicular moment arm distance from the axis of rotation.
Question 6: In a first-class lever system, where is the fulcrum positioned relative to the effort and resistance?
- At the same end as the resistance
- At the same end as the effort
- Between the effort and resistance (Correct answer)
- Beyond the resistance
Correct answer: Between the effort and resistance
In a first-class lever, the fulcrum (axis) lies between the effort force and the resistance, as seen with a seesaw.
Question 7: What does the term 'stiffness' refer to in the context of musculotendinous biomechanics?
- The ability of a muscle to resist fatigue
- The ratio of force to deformation in a structure (Correct answer)
- The maximum force a tendon can absorb before rupture
- The rate of calcium release from the sarcoplasmic reticulum
Correct answer: The ratio of force to deformation in a structure
Stiffness is defined as the slope of the force-deformation (stress-strain) curve, representing resistance to deformation per unit of applied force.
CSCS CSCS: Biomechanics of Resistance 2
What is the mechanical advantage of a muscle-joint system when the moment arm of the muscle force is shorter than the moment arm of the external load?