NCBTMB Kinesiology and Biomechanics Questions and Answers — Questions and Answers
Question 1: A client is performing a standing calf raise, pushing their body weight up onto the balls of their feet. This action at the ankle joint represents which class of lever?
- First-class lever
- Second-class lever (Correct answer)
- Third-class lever
- Fourth-class lever
Correct answer: Second-class lever
In a standing calf raise, the axis (fulcrum) is the metatarsophalangeal joints, the resistance is the body's weight acting through the ankle, and the force is applied by the gastrocnemius and soleus muscles to the calcaneus. Since the resistance is located between the fulcrum and the force, this is a second-class lever.
Question 2: During the swing phase of the gait cycle, a client's foot catches the ground. Weakness in which muscle group is most likely contributing to this issue, commonly known as 'foot drop'?
- Plantar flexors
- Hip flexors
- Knee extensors
- Dorsiflexors (Correct answer)
Correct answer: Dorsiflexors
The swing phase of gait requires the foot to clear the ground. This is accomplished by dorsiflexion at the ankle, primarily by the tibialis anterior and other dorsiflexor muscles. Weakness in these muscles can lead to an inability to lift the foot sufficiently, causing it to drag or catch, a condition known as foot drop.
Question 3: A massage therapist is working with a client to increase shoulder abduction range of motion. The therapist notes that for smooth, full-range movement to occur, the deltoid and the rotator cuff muscles must work together synergistically. What is this biomechanical relationship called?
- Agonist-antagonist pairing
- Reciprocal inhibition
- Force-couple (Correct answer)
- Length-tension relationship
Correct answer: Force-couple
A force-couple is when two or more muscles pull in different directions on an object to produce rotation. During shoulder abduction, the deltoid pulls the humerus upward, while the rotator cuff muscles (subscapularis, infraspinatus, and teres minor) pull the humeral head downward and into the glenoid fossa. This coordinated action allows for smooth rotation and prevents impingement.
Question 4: Which of the following describes a closed kinetic chain exercise?
- Bicep curl with a dumbbell
- Leg extension on a machine
- Push-up (Correct answer)
- Lateral raise with a resistance band
Correct answer: Push-up
In a closed kinetic chain exercise, the distal segment of the limb (the hand or foot) is fixed and stationary against a surface. During a push-up, the hands are fixed to the floor, and the body moves around them. The other options are open kinetic chain exercises because the hand or foot is free to move.
Question 5: A therapist is instructing a client on an exercise to strengthen their rhomboids. The client is asked to slowly pull a resistance band towards their chest while squeezing their shoulder blades together. What type of muscle contraction are the rhomboids performing during this pulling phase?
- Isometric
- Eccentric
- Concentric (Correct answer)
- Isokinetic
Correct answer: Concentric
A concentric contraction occurs when a muscle shortens while generating force. In this scenario, the rhomboids are the prime movers for scapular retraction. As the client pulls the band, the rhomboids shorten to bring the scapulae closer to the spine, thus performing a concentric contraction.
Question 6: The articulation between the first carpal (trapezium) and the first metacarpal of the thumb is a classic example of which type of synovial joint, allowing for flexion, extension, abduction, adduction, and opposition?
- Hinge joint
- Ball-and-socket joint
- Pivot joint
- Saddle joint (Correct answer)
Correct answer: Saddle joint
A saddle joint is where two bones, each with a concave and convex surface, articulate with each other, fitting together like a rider on a saddle. This structure allows for biaxial movement (flexion/extension and abduction/adduction) as well as circumduction and opposition. The carpometacarpal joint of the thumb is the primary example of a saddle joint in the human body.
NCBTMB Kinesiology and Biomechanics Questions and Answers
A client is performing a standing calf raise, pushing their body weight up onto the balls of their feet.
This action at the ankle joint represents which class of lever?