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NESTA Biomechanics Specialist study materials
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NESTA Biomechanics Specialist practice questions

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Question 1Anatomical and Biomechanical Foundations

In anatomical position, which plane divides the body into equal left and right halves?

  1. Midsagittal plane Correct answer.
  2. Transverse plane
  3. Frontal plane
  4. Oblique plane

Explanation

The midsagittal (median) plane passes vertically through the midline and creates equal left and right halves. Sagittal planes generally divide the body into left and right portions, but only the midsagittal plane bisects it equally. Frontal and transverse planes divide the body along different axes entirely.

Question 2Anatomical and Biomechanical Foundations

A lever in which the fulcrum lies between the applied force and the resistance is classified as which class?

  1. Fourth class
  2. Third class
  3. First class Correct answer.
  4. Second class

Explanation

A first-class lever places the fulcrum between the effort and the load, like a seesaw. The arrangement of the three points determines the class, and only first-class levers have the axis in the middle. Second- and third-class levers place the resistance and effort between the other components respectively.

Question 3Anatomical and Biomechanical Foundations

Which connective tissue structure attaches muscle to bone and transmits contractile force to the skeleton?

  1. Ligament
  2. Tendon Correct answer.
  3. Bursa
  4. Fascia

Explanation

Tendons are dense regular connective tissues that connect muscle to bone and transmit tensile force generated by the muscle. Their collagen alignment along the line of pull makes them well suited to withstand tension. Ligaments connect bone to bone, while fascia and bursae serve different mechanical roles.

Question 4Anatomical and Biomechanical Foundations

During a biceps curl, the elbow flexes while the hand moves toward the shoulder. What is the role of the biceps brachii in this action?

  1. Neutralizer
  2. Agonist Correct answer.
  3. Stabilizer
  4. Antagonist

Explanation

The muscle producing the desired movement is the agonist (prime mover); the biceps brachii generates the flexion torque here. Antagonists oppose the movement, while stabilizers and neutralizers serve other roles. Identifying the agonist depends on the specific joint action being performed.

Question 5Anatomical and Biomechanical Foundations

Which type of muscle contraction produces tension while the muscle lengthens?

  1. Isometric
  2. Eccentric Correct answer.
  3. Isokinetic
  4. Concentric

Explanation

An eccentric contraction occurs when the muscle develops tension while lengthening, often to control or decelerate a load. Concentric contractions shorten the muscle, and isometric contractions hold length constant. Isokinetic refers to constant angular velocity rather than a lengthening action.

Question 6Anatomical and Biomechanical Foundations

According to the sliding filament theory, what directly causes sarcomere shortening?

  1. Titin filaments contracting actively
  2. Actin filaments lengthening
  3. Myosin heads pulling actin filaments toward the sarcomere center Correct answer.
  4. Z-lines moving farther apart

Explanation

Myosin cross-bridges bind actin and undergo a power stroke, sliding actin filaments toward the sarcomere center and shortening the sarcomere. The filaments themselves do not change length during contraction. The Z-lines move closer together as a result of this sliding.

Question 7Anatomical and Biomechanical Foundations

Which muscle fiber type is characterized by a high oxidative capacity and resistance to fatigue?

  1. Type IIa
  2. Type I Correct answer.
  3. Type IIb
  4. Type IIx

Explanation

Type I (slow-twitch) fibers have abundant mitochondria, high myoglobin content, and rich capillary supply, giving them strong oxidative capacity and fatigue resistance. Type II fibers rely more on glycolytic metabolism and fatigue faster. Type IIa is intermediate but less fatigue-resistant than Type I.

Question 8Anatomical and Biomechanical Foundations

In the standard anatomical position, the palms of the hands face which direction?

  1. Laterally
  2. Anteriorly Correct answer.
  3. Inferiorly
  4. Posteriorly

Explanation

Anatomical position places the body upright with arms at the sides and palms facing forward, which is anteriorly. This reference orientation standardizes descriptions of movement and location. Deviating from it, such as palms facing backward, changes how terms like supination and pronation are described.

Question 9Anatomical and Biomechanical Foundations

A force of 200 N is applied at a perpendicular distance of 0.25 m from a joint axis. What torque is produced about that axis?

  1. 500 N·m
  2. 800 N·m
  3. 50 N·m Correct answer.
  4. 25 N·m

Explanation

Torque equals force multiplied by the perpendicular moment arm, so 200 N × 0.25 m = 50 N·m. The moment arm must be measured perpendicular to the line of action. Dividing or multiplying the two values incorrectly produces the other options.

Question 10Anatomical and Biomechanical Foundations

Why do most human limb muscles operate as third-class levers?

  1. They maximize force output at the expense of speed
  2. They eliminate the need for a fulcrum
  3. They place the effort between the fulcrum and the load, favoring speed and range of motion Correct answer.
  4. They place the load between the fulcrum and the effort

Explanation

In most limb joints the muscle insertion lies between the joint axis and the load, making the effort the middle component of a third-class lever. This arrangement favors speed and range of motion at the distal segment while requiring greater muscle force. It is mechanically disadvantageous for force but advantageous for movement velocity.

Question 11Anatomical and Biomechanical Foundations

As a muscle shortens from its resting length toward a very short length, what generally happens to its active force-producing capacity?

  1. It stays constant regardless of length
  2. It increases continuously
  3. It increases only at the shortest lengths
  4. It decreases due to reduced actin-myosin overlap Correct answer.

Explanation

Active tension depends on cross-bridge formation, which is greatest at an optimal overlap of actin and myosin. At very short lengths, filaments overlap excessively and interfere with cross-bridge cycling, reducing active force. The length-tension relationship therefore peaks near resting length and declines at extremes.

Question 12Anatomical and Biomechanical Foundations

Which factor increases the moment arm of a muscle about a joint?

  1. Increasing the perpendicular distance from the joint axis to the muscle's line of action Correct answer.
  2. Shortening the bone segment distal to the joint
  3. Reducing the muscle's cross-sectional area
  4. Decreasing the angle between the tendon and the bone to zero

Explanation

The moment arm is the perpendicular distance from the joint axis to the line of action of the muscle force. Increasing that perpendicular distance increases torque for a given force. When the tendon angle approaches zero or 180 degrees, the moment arm shrinks toward zero.

Question 13Anatomical and Biomechanical Foundations

Which statement correctly describes the role of the antagonist muscle during a controlled movement?

  1. It has no mechanical influence during movement
  2. It generates the primary torque for the action
  3. It often lengthens under tension to control and refine the movement Correct answer.
  4. It always relaxes completely to allow movement

Explanation

Antagonists frequently undergo eccentric lengthening under tension, which helps control joint motion and add stability. This coactivation refines movement rather than simply opposing it. Complete relaxation of antagonists is not required and would reduce control.

Question 14Anatomical and Biomechanical Foundations

A runner lands with the knee flexed and the hip flexed. How does this positioning affect the ground reaction force attenuation compared with a stiff, extended leg landing?

  1. It increases peak impact forces because of greater muscle activation
  2. It increases the time over which the body decelerates, reducing peak forces Correct answer.
  3. It has no effect on force attenuation
  4. It eliminates ground reaction forces entirely

Explanation

Greater joint flexion during landing lengthens the deceleration phase, which lowers the peak ground reaction force for a given change in momentum. This is an application of the impulse-momentum relationship. A stiff landing shortens the deceleration time and raises peak forces.

Question 15Anatomical and Biomechanical Foundations

Which term describes a movement of the forearm that turns the palm to face downward?

  1. Supination
  2. Inversion
  3. Pronation Correct answer.
  4. Eversion

Explanation

Pronation rotates the forearm so the palm faces downward or posteriorly, driven by the pronator teres and pronator quadratus. Supination is the opposite motion, turning the palm upward. Inversion and eversion describe foot movements.

Question 16Anatomical and Biomechanical Foundations

Which structure primarily resists excessive anterior translation of the tibia relative to the femur?

  1. Patellar tendon
  2. Posterior cruciate ligament
  3. Medial collateral ligament
  4. Anterior cruciate ligament Correct answer.

Explanation

The anterior cruciate ligament restrains anterior tibial translation and limits excessive internal rotation. The posterior cruciate ligament resists posterior tibial translation. Collateral ligaments and the patellar tendon serve different stabilizing roles.

Question 17Anatomical and Biomechanical Foundations

According to Newton's third law, what happens when a sprinter pushes backward against the ground?

  1. The ground pushes the sprinter forward with an equal and opposite force Correct answer.
  2. The ground exerts no reaction force
  3. The reaction force is always smaller than the action force
  4. The sprinter's mass decreases

Explanation

Newton's third law states that every action has an equal and opposite reaction. The sprinter's backward push against the ground generates a forward ground reaction force of equal magnitude. This forward force propels the athlete, and the equal magnitude is not reduced by the reaction.

Question 18Anatomical and Biomechanical Foundations

During a squat, the quadriceps and hamstrings co-contract. What is a primary biomechanical consequence of this co-contraction at the knee?

  1. It increases joint compression while improving joint stability Correct answer.
  2. It reduces joint compression and increases shear equally
  3. It eliminates all joint reaction forces
  4. It prevents any muscle force generation

Explanation

Co-contraction increases compressive joint reaction forces because both muscle groups pull across the joint, but it also enhances stability and control. The net effect involves a trade-off between stability and loading. It does not eliminate joint forces.

Question 19Anatomical and Biomechanical Foundations

Which property of viscoelastic tissue describes its tendency to deform gradually under a sustained constant load?

  1. Anisotropy
  2. Thixotropy
  3. Elastic recoil
  4. Creep Correct answer.

Explanation

Creep is the progressive deformation of a viscoelastic material under constant sustained load. Elastic recoil is the return to original shape after load removal. Thixotropy and anisotropy describe different time- and direction-dependent behaviors.

Question 20Anatomical and Biomechanical Foundations

A muscle's force-generating capacity is best estimated by which anatomical measure?

  1. Joint angle
  2. Physiological cross-sectional area Correct answer.
  3. Tendon length
  4. Muscle length

Explanation

Physiological cross-sectional area reflects the number of sarcomeres in parallel and correlates strongly with maximum force production. Muscle length influences excursion and the length-tension relationship rather than peak force capacity. Tendon length and joint angle affect leverage and motion, not intrinsic force capacity.

Question 21Anatomical and Biomechanical Foundations

A muscle with a pennate fiber arrangement compared with a fusiform muscle of equal volume typically demonstrates which trade-off?

  1. Greater force output and shorter fiber excursion Correct answer.
  2. Greater excursion and greater force output
  3. Equal force and equal excursion
  4. Greater excursion and lower force output

Explanation

Pennate muscles pack more fibers at an angle to the line of pull, increasing physiological cross-sectional area and force capacity. The angled arrangement, however, reduces the distance the tendon travels, limiting excursion and contraction velocity. Fusiform muscles favor excursion over force.

Question 22Anatomical and Biomechanical Foundations

During the stance phase of gait, the center of pressure typically moves in which pattern beneath the foot?

  1. From the toes directly to the heel
  2. From the heel, along the lateral border, across the forefoot, and toward the medial toes Correct answer.
  3. From the heel laterally to the toes in a straight line
  4. It remains fixed at the midfoot

Explanation

The center of pressure progresses from the heel at initial contact, along the lateral midfoot, then medially across the metatarsal heads toward the great toe during push-off. This path reflects the transfer of load through the foot. It does not remain stationary or move in reverse.

Question 23Anatomical and Biomechanical Foundations

Why does a muscle's torque-generating ability vary across joint range even when activation is maximal?

  1. Because muscle force and moment arm both change with joint angle Correct answer.
  2. Because muscle mass changes with joint angle
  3. Because tendon stiffness is constant at all angles
  4. Because gravity is absent at certain angles

Explanation

Joint torque is the product of muscle force and moment arm, and both vary with joint angle. The length-tension relationship alters force, while changing the angle of the tendon relative to the bone alters the moment arm. Their interaction produces a torque-angle curve that peaks at an intermediate joint position.

Question 24Anatomical and Biomechanical Foundations

In a two-dimensional free-body analysis of a held dumbbell at the shoulder, which combination correctly represents the moments about the glenohumeral joint?

  1. Moments need not balance because the arm is stationary
  2. Only the muscle force creates a moment
  3. The dumbbell weight and the muscle force both create moments that must balance for static equilibrium Correct answer.
  4. Only the dumbbell weight creates a moment

Explanation

For static equilibrium, the sum of moments about the joint must equal zero, so the moment from the dumbbell weight is balanced by the opposing moment from the shoulder muscles. Both forces act at perpendicular distances from the joint axis. Ignoring either moment violates rotational equilibrium.

Question 25Anatomical and Biomechanical Foundations

Which statement best explains why eccentric contractions can generate greater force than concentric contractions at the same angular velocity?

  1. The moment arm increases only during eccentric actions
  2. Fewer active cross-bridges are required to produce force
  3. Cross-bridges are forcibly detached by external load, and elastic elements contribute to force Correct answer.
  4. Muscle temperature drops during lengthening

Explanation

During eccentric action, external load stretches the muscle, forcibly detaching cross-bridges and allowing repeated high-force attachments, while elastic elements store and return energy. These factors allow greater force than concentric action at matched velocity. Moment arm changes are not specific to eccentric contraction.

Question 26Anatomical and Biomechanical Foundations

In a biomechanical analysis, a movement is described as occurring in the sagittal plane. About which axis does this motion primarily take place?

  1. Mediolateral axis Correct answer.
  2. Frontal (coronal) axis
  3. Anteroposterior axis
  4. Vertical (longitudinal) axis

Explanation

Each anatomical plane is defined by the axis perpendicular to it. The sagittal plane divides the body into left and right portions, and motion within it (flexion, extension) rotates about a mediolateral axis running side to side. The frontal axis is the same structure described differently, so candidates must recognize the standard term for the axis perpendicular to the sagittal plane.

Question 27Anatomical and Biomechanical Foundations

A therapist wants to reduce the external flexion torque created by a handheld load on the shoulder. Holding the load mass and the joint angle constant, which change achieves this most directly?

  1. Rotating the load so its mass is distributed more distally
  2. Moving the load closer to the shoulder joint Correct answer.
  3. Extending the elbow to lengthen the lever arm
  4. Increasing the speed of the lifting movement

Explanation

External torque equals force multiplied by the perpendicular moment arm from the joint axis. With load mass and joint angle fixed, the only way to lower torque is to shorten the horizontal distance between the load and the joint, which moving it closer to the shoulder accomplishes. Speed and mass distribution along the segment do not change the perpendicular distance of the load's center of mass.

Question 28Anatomical and Biomechanical Foundations

Two muscles cross the same joint with identical peak force capability, but muscle A has a larger physiological cross-sectional area while muscle B has a longer fiber length. Which interpretation best reflects the trade-off between these architectural properties?

  1. Both muscles generate equal force and velocity because peak force depends only on muscle volume
  2. Muscle A favors greater excursion because larger cross-sectional area increases fiber shortening distance
  3. Muscle B can produce greater peak force because longer fibers contain more sarcomeres in series
  4. Muscle A can produce greater peak force, while muscle B favors greater shortening velocity and excursion Correct answer.

Explanation

Physiological cross-sectional area reflects the number of sarcomeres in parallel and therefore sets force-generating capacity, whereas fiber length reflects sarcomeres in series and sets maximum shortening velocity and excursion. Thus the muscle with greater cross-sectional area is biased toward force and the longer-fibered muscle toward speed and range. Volume alone does not determine either property independently.

Question 29Kinesiology and Functional Anatomy

In the sagittal plane, which joint action describes decreasing the angle between the anterior thigh and the anterior trunk?

  1. Hip external rotation
  2. Hip flexion Correct answer.
  3. Hip abduction
  4. Hip extension

Explanation

Hip flexion moves the femur anteriorly toward the pelvis in the sagittal plane, reducing the angle between the thigh and trunk. This action is produced concentrically by the iliopsoas, rectus femoris, and sartorius during movements such as a knee lift.

Question 30Kinesiology and Functional Anatomy

A lever system in which the effort is applied between the fulcrum and the load is classified as which class?

  1. Third class Correct answer.
  2. Fourth class
  3. First class
  4. Second class

Explanation

In a third-class lever the effort force lies between the axis (fulcrum) and the resistance, so the effort arm is always shorter than the load arm. Most human limb motions, such as elbow flexion by the biceps brachii, follow this arrangement, which favors speed and range of motion over force magnification.

Question 31Kinesiology and Functional Anatomy

Which muscle acts primarily as a hip extensor during the stance-to-push-off phase of running?

  1. Gluteus maximus Correct answer.
  2. Tensor fasciae latae
  3. Pectineus
  4. Iliacus

Explanation

The gluteus maximus is the largest and most powerful hip extensor, generating the propulsive extension seen near toe-off in running. Its broad origin on the ilium and posterior sacrum gives it a long moment arm for extension.

Question 32Kinesiology and Functional Anatomy

Which structure is the primary restraint to anterior translation of the tibia relative to the femur?

  1. Medial collateral ligament
  2. Patellar tendon
  3. Posterior cruciate ligament
  4. Anterior cruciate ligament Correct answer.

Explanation

The anterior cruciate ligament runs from the anterior tibial plateau to the posterior medial femoral condyle, resisting anterior tibial translation and internal tibial rotation. It is the structure loaded during deceleration and cutting tasks that stress the knee.

Question 33Kinesiology and Functional Anatomy

During a biceps curl, the biceps brachii shortens while producing tension. Which contraction type is occurring?

  1. Concentric Correct answer.
  2. Isometric
  3. Eccentric
  4. Isokinetic

Explanation

A concentric contraction produces force while the muscle shortens, which is the phase that lifts the load against gravity in a curl. The elbow flexors generate tension and their attachments move closer together.

Question 34Kinesiology and Functional Anatomy

Which muscle group constitutes the primary dynamic stabilizers that prevent excessive valgus collapse of the knee during a single-leg squat?

  1. Knee flexors
  2. Hip abductors and external rotators Correct answer.
  3. Ankle dorsiflexors
  4. Hip adductors

Explanation

The gluteus medius and associated external rotators control femoral adduction and internal rotation, keeping the knee aligned over the foot. When these muscles are weak, the femur collapses inward and dynamic valgus stress rises.

Question 35Kinesiology and Functional Anatomy

Which term describes the angle between a muscle's line of pull and the bone it moves, measured at the joint?

  1. Angle of insertion
  2. Angle of torsion
  3. Angle of pennation
  4. Angle of pull Correct answer.

Explanation

The angle of pull is the angle formed between the muscle's line of action and the lever (bone) at the joint. It determines how much of the muscle force contributes to rotation versus joint compression or distraction.

Question 36Kinesiology and Functional Anatomy

A client performs a lateral lunge and the coach notes the moving femur travels away from the midline in the frontal plane. Which axis is this motion occurring about?

  1. Anteroposterior axis Correct answer.
  2. Longitudinal axis
  3. Vertical axis
  4. Mediolateral axis

Explanation

Frontal-plane abduction and adduction rotate about an anteroposterior axis running front to back through the joint. Because the segment sweeps side to side, the axis of rotation must point forward and backward.

Question 37Kinesiology and Functional Anatomy

Why does the patella increase the extension torque available at the knee?

  1. It increases the physiologic cross-sectional area of the quadriceps
  2. It reduces the distance from the knee axis to the tibial tuberosity
  3. It converts the quadriceps into a second-class lever
  4. It increases the moment arm of the quadriceps about the knee axis Correct answer.

Explanation

By holding the quadriceps tendon away from the femoral condyles, the patella increases the perpendicular distance from the knee axis to the line of pull. A larger moment arm yields greater torque for the same muscle force, which is why patellectomy reduces extension strength.

Question 38Kinesiology and Functional Anatomy

A lifter holds a 30 kg barbell 0.30 m from the elbow axis while the forearm is horizontal. Ignoring forearm mass, what is the flexion moment created by the load?

  1. 9 N·m
  2. 900 N·m
  3. 88 N·m Correct answer.
  4. 0.9 N·m

Explanation

Moment equals force times perpendicular distance, so 30 kg × 9.81 m/s² ≈ 294 N multiplied by 0.30 m gives about 88 N·m. The elbow flexors must produce an equal and opposite internal moment to hold the position statically.

Question 39Kinesiology and Functional Anatomy

As a joint moves through its range, the moment arm of a muscle changes. What torque profile does a muscle with a short moment arm typically display?

  1. Torque that peaks only at end range
  2. High torque at low muscle force
  3. Torque independent of muscle force
  4. Low torque even at high muscle force Correct answer.

Explanation

Torque is the product of muscle force and moment arm, so a short moment arm limits torque output regardless of how much tension the muscle develops. This explains why muscles with small moment arms rely on high force or larger cross-sectional area to contribute meaningful joint torque.

Question 40Kinesiology and Functional Anatomy

Which change best explains why older adults often show reduced peak power during a chair-rise task?

  1. Increased tendon compliance only
  2. Increased muscle pennation angle
  3. Increased type II fiber recruitment
  4. Decreased rate of force development Correct answer.

Explanation

Peak power depends on how quickly force can be produced, and aging is associated with reduced rate of force development and preferential loss of fast-twitch motor units. Slower force rise means the chair-rise is completed with less explosive hip and knee extension.

Question 41Kinesiology and Functional Anatomy

Which muscle is a two-joint hip flexor and knee extensor whose action is affected by simultaneous movement at both joints?

  1. Vastus lateralis
  2. Rectus femoris Correct answer.
  3. Gluteus medius
  4. Biceps femoris

Explanation

The rectus femoris crosses both the hip and knee, so its length change depends on the combined joint angles, a phenomenon called active insufficiency when it shortens over both joints. This is why full hip flexion plus knee extension reduces its capacity to generate knee extension force.

Question 42Kinesiology and Functional Anatomy

During the lowering phase of a squat, which combination of contraction types occurs at the knee extensors?

  1. Passive shortening with no active tension
  2. Concentric shortening while resisting gravity
  3. Isometric tension with no length change
  4. Eccentric lengthening while resisting gravity Correct answer.

Explanation

In the descent, the quadriceps lengthen under tension to control the rate of knee flexion against gravity, which is an eccentric contraction. This braking action dissipates energy and is a common source of delayed-onset muscle soreness.

Question 43Kinesiology and Functional Anatomy

A runner exhibits excessive contralateral pelvic drop during single-leg stance. Which muscle is the most likely primary contributor to this fault?

  1. Gastrocnemius of the stance limb
  2. Rectus abdominis
  3. Iliopsoas of the swing limb
  4. Gluteus medius of the stance limb Correct answer.

Explanation

The gluteus medius on the stance side contracts to keep the pelvis level in the frontal plane. When it is weak or poorly timed, the opposite side of the pelvis drops, a pattern known as Trendelenburg gait.

Question 44Kinesiology and Functional Anatomy

Which statement correctly describes the relationship between muscle force and joint angle during an isometric contraction?

  1. Force is unrelated to sarcomere overlap
  2. Force peaks only at full flexion
  3. Force is constant across all joint angles
  4. Force varies with the length-tension relationship and moment arm Correct answer.

Explanation

Isometric force changes with joint angle because sarcomere length alters actin-myosin overlap and because the moment arm varies through the range. The resulting joint torque reflects both the length-tension curve and the changing moment arm.

Question 45Kinesiology and Functional Anatomy

Which biomechanical principle explains why a longer bat can increase swing speed at the barrel but also increase the difficulty of controlling the swing?

  1. Poiseuille's law
  2. Conservation of angular momentum
  3. Moment of inertia and angular acceleration Correct answer.
  4. Hooke's law

Explanation

A longer implement increases its moment of inertia about the rotation center, so more torque is needed to accelerate it, but the greater radius raises linear speed at the tip once rotation is achieved. This trade-off between speed potential and control underlies implement selection in striking sports.

Question 46Kinesiology and Functional Anatomy

Which structure provides the primary restraint against anterior humeral head translation in the abducted, externally rotated shoulder?

  1. Long head of the biceps tendon
  2. Coracoacromial ligament
  3. Anterior band of the inferior glenohumeral ligament Correct answer.
  4. Supraspinatus tendon

Explanation

In abduction and external rotation, the anterior band of the inferior glenohumeral ligament becomes the key static restraint to anterior translation, a position used in apprehension testing. Its failure contributes to anterior instability in throwing athletes.

Question 47Kinesiology and Functional Anatomy

Which factor most directly determines the mechanical advantage of the calf muscles during a heel raise?

  1. The length of the tibia
  2. The width of the foot
  3. The angle of the knee only
  4. The moment arm of the Achilles tendon at the ankle Correct answer.

Explanation

Mechanical advantage depends on the ratio of the effort moment arm to the resistance moment arm, and for the plantar flexors the Achilles tendon moment arm at the talocrural joint is the effort arm. A larger tendon moment arm reduces the muscle force needed to support the same body weight.

Question 48Kinesiology and Functional Anatomy

A therapist observes that a client cannot fully extend the knee when the hip is fully flexed. Which concept best explains this limitation?

  1. Active insufficiency of the quadriceps
  2. Passive insufficiency of the hamstrings Correct answer.
  3. Eccentric failure of the gastrocnemius
  4. Reciprocal inhibition of the gluteals

Explanation

The hamstrings cross both the hip and knee, so full hip flexion already lengthens them proximally, limiting further lengthening at the knee and blocking terminal knee extension. This is passive insufficiency, where the muscle cannot stretch enough to permit the combined joint positions.

Question 49Kinesiology and Functional Anatomy

During sprinting, the swing leg flexes at the hip while extending at the knee. What effect does this combined motion have on the rectus femoris?

  1. It lengthens over the hip and shortens over the knee, keeping length relatively stable Correct answer.
  2. It shortens at both joints, producing active insufficiency
  3. It remains isometric at both joints
  4. It lengthens at both joints, producing passive tension

Explanation

Because the rectus femoris crosses the hip as a flexor and the knee as an extensor, hip flexion lengthens it while knee extension shortens it, so the net length change can be small. This offset lets the muscle contribute at both joints without extreme shortening during the swing phase.

Question 50Kinesiology and Functional Anatomy

A jump-landing assessment shows the knees reaching 60 degrees of flexion while the hips remain nearly extended. Which biomechanical consequence is most likely?

  1. Increased reliance on the quadriceps and greater patellofemoral stress Correct answer.
  2. Increased hip extensor demand with unchanged knee load
  3. Reduced ground reaction force through the entire limb
  4. Decreased anterior tibial translation due to hip position

Explanation

Landing with limited hip flexion shifts the absorption demand to the knee, requiring larger quadriceps forces and raising patellofemoral joint stress. A more hip-dominant strategy distributes the load across larger hip extensors and reduces strain on the knee.