Massage and Bodywork Licensing Examination MBLEx Test Kinesiology and Biomechanics 1 — Questions and Answers
Question 1: When the biceps brachii flexes the elbow joint, with the elbow acting as the fulcrum and a weight held in the hand as the load, which class of lever is demonstrated?
- First class
- Second class
- Third class (Correct answer)
- Fourth class
Correct answer: Third class
In elbow flexion, the muscle force (effort) is applied at the biceps insertion on the radius, which lies between the fulcrum (elbow joint) and the load (weight in hand). This arrangement defines a third-class lever, the most common lever type found in the human body.
Question 2: Which sensory receptor detects rapid changes in muscle length and initiates the stretch reflex arc?
- Golgi tendon organ
- Pacinian corpuscle
- Muscle spindle (Correct answer)
- Ruffini ending
Correct answer: Muscle spindle
Muscle spindles are proprioceptors embedded within the muscle belly that monitor changes in muscle length. When a muscle is suddenly lengthened, spindle activation sends afferent signals to the spinal cord, triggering a reflexive contraction of the same muscle to resist the stretch.
Question 3: A muscle that assists the prime mover by contributing to the same joint action is classified as a:
- Antagonist
- Fixator
- Neutralizer
- Synergist (Correct answer)
Correct answer: Synergist
A synergist aids the agonist (prime mover) by performing the same or a supporting joint action, or by stabilizing proximal joints so the prime mover can work efficiently. Antagonists, by contrast, produce the opposite motion.
Question 4: During a closed kinetic chain exercise such as a standing squat, what best characterizes the distal segment?
- It moves freely through space
- It is fixed against an immovable surface (Correct answer)
- It acts as the primary axis of rotation
- It undergoes only eccentric contractions
Correct answer: It is fixed against an immovable surface
In a closed kinetic chain, the distal segment (e.g., the foot in a squat) is fixed against a surface, causing the proximal segments to move around it. This contrasts with an open kinetic chain, where the distal segment swings freely through space.
Question 5: Which type of muscle contraction occurs when the muscle generates tension but neither the joint angle nor the muscle length changes?
- Eccentric
- Concentric
- Isometric (Correct answer)
- Isokinetic
Correct answer: Isometric
An isometric contraction ('iso' = same, 'metric' = length/measure) produces force without any shortening or lengthening of the muscle or movement at the joint. It is commonly seen in postural stabilization and static holds.
Question 6: Movements occurring in the sagittal plane, such as flexion and extension, rotate around which axis of motion?
- Vertical (longitudinal) axis
- Mediolateral (frontal) axis (Correct answer)
- Anteroposterior (sagittal) axis
- Oblique axis
Correct answer: Mediolateral (frontal) axis
Each plane of motion is paired with a perpendicular axis of rotation. Sagittal plane movements (flexion and extension) occur around the mediolateral axis, which runs horizontally from side to side through the body. The axis is always perpendicular to its corresponding plane.
Massage and Bodywork Licensing Examination MBLEx Test Kinesiology and Biomechanics 1
When the biceps brachii flexes the elbow joint, with the elbow acting as the fulcrum and a weight held in the hand as the load, which class of lever is demonstrated?