This practice set contains high-yield board review questions covering key concepts in Physiology & Rehabilitation. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 121
Topic: Physiology & Rehabilitation
Delayed-onset muscle soreness (DOMS) is initially evident at the muscle tendon junction and can spread throughout the entire muscle. It is primarily associated with what type of exercise? Review Topic
Correct Answer & Explanation
. Concentric
Explanation
DOMS is primarily associated with eccentric exercise because fiber lengthening occurs during muscle contraction. Muscle injury occurs very early during eccentric exercise, with structural disruption of the cytoskeleton. A significant increase in creatine kinase levels occurs 24 to 48 hours after exercise and may peak between 3 to 6 days after exercise. All other choices are not strongly associated with delayed muscle soreness.
Question 122
Topic: Physiology & Rehabilitation
During the stance phase of the normal human gait cycle, the joint reaction force across the hip joint typically peaks at approximately what multiple of body weight?
Correct Answer & Explanation
. 1 times body weight
Explanation
During normal walking, the hip joint reaction force peaks at approximately 2.5 to 3 times body weight during the stance phase. This force is the vector sum of body weight acting on a longer lever arm and the substantial counterbalancing pull of the abductor musculature acting on a shorter lever arm.
Question 123
Topic: Physiology & Rehabilitation
Endurance training stimulates which of the following physiologic adaptations in the athlete? Review Topic
Correct Answer & Explanation
. Increased storage and utilization of intramuscular lipids
Explanation
Endurance training causes selective hypertrophy of type I muscle fibers. It stimulates an increase in the enzymes of the Krebs cycle which increases the capacity for aerobic ATP resynthesis during exercise. There is a decrease in the rate of glycogen depletion. Depletion of glycogen has been linked to fatigue during endurance exercise. Endurance training blunts the catecholamine response and may contribute to the reduction in heart rate observed for the same exercise intensity following training. The greater use of lipid reduces the contribution of carbohydrate to ATP resynthesis and preserves muscle glycogen.
Question 124
Topic: Physiology & Rehabilitation
A 28-year-old marathon runner presents with lateral knee pain that worsens after 3 miles of running. Examination reveals tenderness over the lateral femoral epicondyle, particularly when the knee is flexed to 30 degrees. The underlying pathophysiology of this condition involves friction of the iliotibial band over the lateral epicondyle during which phase of the gait cycle?
Correct Answer & Explanation
. Foot strike (early stance phase)
Explanation
Iliotibial (IT) band friction syndrome occurs as the IT band passes back and forth over the lateral femoral epicondyle. Maximum friction typically occurs at approximately 30 degrees of knee flexion. During running, the knee is at roughly 30 degrees of flexion at foot strike (early stance phase), which is when the impingement and pain are most pronounced.
Question 125
Topic: Physiology & Rehabilitation
What is the primary goal of the initial (acute) rehabilitation phase of an overhead athlete's shoulder?
Correct Answer & Explanation
. Improve flexibility
Explanation
The goal in the initial phase of shoulder rehabilitation is to improve flexibility, reestablish baseline dynamic stability, normalize muscle balance, and restore proprioception. In the advanced strengthening and final phase, the goals are to initiate aggressive strengthening drills, enhance power and endurance, perform functional drills, and to gradually initiate throwing activities.
Question 126
Topic: Physiology & Rehabilitation
A college football player performs bicep curls as part of his weight lifting routine. During the flexion phase of the curl, what term defines the type of muscle contraction?
Correct Answer & Explanation
. Isotonic
Explanation
DISCUSSION: Muscle contractions can be classified by tension, length, and velocity. Isometric contractions involve changing tension in the muscle while the muscle stays at a constant length. An example would be pushing against a wall. Isokinetic contractions occur when the muscle maximally contracts at a constant velocity. Isotonic contractions involve constant tension throughout the range of motion. Eccentric contraction is when the muscle lengthens during contraction. Eccentric contractions have the highest risk of injury. Plyometrics are eccentric contractions at a rapid rate. REFERENCES: Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 89-125. Evans WJ: Effects of exercise on senescent muscle. Clin Orthop 2002;403:S211-S220.
Question 127
Topic: Physiology & Rehabilitation
A 10-year-old boy with spastic diplegic cerebral palsy walks in a crouched position with the hips and knees flexed. Maximum knee flexion is 15 degrees during early swing phase. Instrumented gait analysis shows quadriceps activity from terminal stance throughout swing phase. Treatment should consist of:
Correct Answer & Explanation
. transfer of the distal rectus femoris tendon.
Explanation
The rectus femoris muscle spans two joints and is active during running, sprinting, and walking at a fast pace during the preswing and early swing phase of gait. In these situations, the muscle helps to generate power to initiate hip flexion while absorbing or controlling the rate of knee flexion during early swing phase. Quadriceps activity, including the rectus femoris, is not normally needed when walking at a routine cadence. However, rectus femoris activity is commonly noted during preswing and the swing phase in patients with cerebral palsy, particularly those with diplegia. In an effort to initiate swing phase, the rectus femoris is overactive. As a result, the knee flexion that commonly occurs at terminal stance and initial swing is restricted. Instead of achieving the normal 50 to 60 degrees of flexion during early swing, this patientโs knee flexion is limited to 15 degrees. The goal of treatment is to retain rectus femoris activity for initiation of hip flexion but to diminish its restraint on knee flexion. Studies have shown that transfer of the distal rectus femoris tendon provides more flexion of the knee during the swing phase of gait than simply releasing the tendon. V-Y lengthening of the quadriceps tendon or a Z lengthening of the patellar tendon causes too much weakening of the quadriceps muscle and worsens the crouch deformity.
Question 128
Topic: Physiology & Rehabilitation
Creatine is currently being used by athletes as a dietary supplement in an attempt to enhance performance. What is the physiologic basis for its use?
Correct Answer & Explanation
. Converts to phosphocreatine (PCr), which acts as an energy reservoir for adenosine triphosphate (ATP) in muscle tissue
Explanation
Creatine is currently used as a nutritional supplement in an attempt to enhance athletic performance. The physiologic basis for its use is based on its conversion by CK to PCr, which acts as an energy reservoir in muscle cells for the production of ATP. A number of studies that examined the effect of creatine supplementation on performance concluded that while creatine does not increase peak force production, it can increase the amount of work done in the first few anaerobic short duration, maximal effort trials. The mechanism for this enhancement of work is unknown, but it is most likely secondary to the increase in the available PCr pool.
Question 129
Topic: Physiology & Rehabilitation
A 60-year-old male with pre-existing cervical spondylosis presents after a hyperextension injury. He has marked weakness in his hands and upper extremities with minimal weakness in his lower extremities. Which of the following best describes the typical pattern of sensory and bladder dysfunction expected in this specific incomplete spinal cord injury syndrome?
Correct Answer & Explanation
. Complete loss of all sensory modalities below the lesion with a flaccid bladder
Explanation
This patient has Central Cord Syndrome, the most common incomplete spinal cord injury, classically seen in older patients with cervical spondylosis who sustain a hyperextension injury. It affects the centrally located cervical tracts supplying the upper extremities more than the peripherally located sacral/lumbar tracts supplying the lower extremities. Sensory loss is variable (often patchy), and bowel/bladder dysfunction (such as urinary retention) may be present but is less severe than in complete lesions.
Question 130
Topic: Physiology & Rehabilitation
During an anterior thoracoabdominal approach for a T10-L2 fusion, the surgeon ligates multiple segmental vessels. Postoperatively, the patient is noted to have loss of bilateral lower extremity motor function and pain/temperature sensation, but preservation of proprioception and light touch. This syndrome is most likely caused by ischemia in the territory of which of the following vessels?
Correct Answer & Explanation
. Artery of Adamkiewicz
Explanation
The clinical picture describes Anterior Spinal Artery (ASA) Syndrome: loss of motor function (corticospinal tracts) and pain/temperature sensation (spinothalamic tracts) with preservation of dorsal column function (proprioception, vibration, light touch). The Artery of Adamkiewicz (arteria radicularis magna) is the major supplier to the anterior spinal artery in the lower thoracic and upper lumbar regions. It typically arises on the left side between T8 and L1. Ligation or injury during anterior approaches can lead to ASA syndrome.
Question 131
Topic: Physiology & Rehabilitation
Which mechanism of injury is most classically responsible for an acute rupture of the pectoralis major tendon?
Correct Answer & Explanation
. Eccentric contraction while the shoulder is extended and externally rotated
Explanation
Pectoralis major ruptures almost exclusively occur during heavy weightlifting, particularly the bench press. The injury happens when the muscle undergoes maximal eccentric contraction with the shoulder extended and externally rotated.
Question 132
Topic: Physiology & Rehabilitation
During the 'screw-home' mechanism of the knee, which muscle is uniquely responsible for 'unlocking' the knee from terminal extension to initiate flexion by internally rotating the tibia relative to the femur?
Correct Answer & Explanation
. Popliteus
Explanation
The popliteus muscle acts to unlock the fully extended knee joint. In an open kinetic chain, it internally rotates the tibia relative to the femur. In a closed kinetic chain, it externally rotates the femur relative to the fixed tibia. It is innervated by the tibial nerve.
Question 133
Topic: Physiology & Rehabilitation
What type of exercise is used early in the rehabilitation process to safely stimulate co-contraction of the scapular and rotator cuff muscles?
Correct Answer & Explanation
. Closed kinetic chain
Explanation
Closed kinetic chain exercises are used early in the rehabilitation process. The distal segment is fixed, and an axial load is applied which provides glenohumeral compression and reduces the demand on the rotator cuff. These exercises stimulate co-contractions of the scapular and rotator cuff muscles, load scapular stabilizers, and facilitate active motion.
Question 134
Topic: Physiology & Rehabilitation
Creatine is currently being used by athletes as a dietary supplement in an attempt to enhance performance. What is the physiologic basis for its use?
Correct Answer & Explanation
. Converts to phosphocreatine (PCr), which acts as an energy reservoir for adenosine triphosphate (ATP) in muscle tissue
Explanation
Creatine is currently used as a nutritional supplement in an attempt to enhance athletic performance. The physiologic basis for its use is based on its conversion by CK to PCr, which acts as an energy reservoir in muscle cells for the production of ATP. A number of studies that examined the effect of creatine supplementation on performance concluded that while creatine does not increase peak force production, it can increase the amount of work done in the first few anaerobic short duration, maximal effort trials. The mechanism for this enhancement of work is unknown, but it is most likely secondary to the increase in the available PCr pool. Greenhaff PL: Creatine and its application as an ergogenic aid. Int J Sport Nutr 1995;5:S100-S110. Greenhaff PL, Casey A, Short AH, Harris R, Soderlund K, Hultman E: Influence of oral creatine supplementation on muscle torque during repeated bouts of maximal voluntary exercise in man. Clin Sci 1993;84:565-571. Trump ME, Heigenhauser GJ, Putman CT, Spriet LL: Importance of muscle phosphocreatine during intermittent maximal cycling. J Appl Physiol 1996;80:1574-1580.
Question 135
Topic: Physiology & Rehabilitation
A 10-year-old boy with spastic diplegic cerebral palsy walks in a crouched position with the hips and knees flexed. Maximum knee flexion is 15 degrees during early swing phase. Instrumented gait analysis shows quadriceps activity from terminal stance throughout swing phase. Treatment should consist of
Correct Answer & Explanation
. transfer of the distal rectus femoris tendon.
Explanation
The rectus femoris muscle spans two joints and is active during running, sprinting, and walking at a fast pace during the preswing and early swing phase of gait. In these situations, the muscle helps to generate power to initiate hip flexion while absorbing or controlling the rate of knee flexion during early swing phase. Quadriceps activity, including the rectus femoris, is not normally needed when walking at a routine cadence. However, rectus femoris activity is commonly noted during preswing and the swing phase in patients with cerebral palsy, particularly those with diplegia. In an effort to initiate swing phase, the rectus femoris is "overactive." As a result, the knee flexion that commonly occurs at terminal stance and initial swing is restricted. Instead of achieving the normal 50 to 60 degrees of flexion during early swing, this patient's knee flexion is limited to 15 degrees. The goal of treatment is to retain rectus femoris activity for initiation of hip flexion but to diminish its restraint on knee flexion. Studies have shown that transfer of the distal rectus femoris tendon provides more flexion of the knee during the swing phase of gait than simply releasing the tendon. V-Y lengthening of the quadriceps tendon or a Z lengthening of the patellar tendon causes too much weakening of the quadriceps muscle and worsens the crouch deformity. In addition to transfer of the rectus femoris tendon, other procedures are often done concomitantly to obtain the best balance and realignment of hip-knee-ankle activity. Aiona MD: Guidelines for managing lower extremity problems in cerebral palsy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1534-1541. Chambers H, Laure A, Kaufman K, Cardelia M, Sutherland D: Prediction of outcome after rectus femoris surgery in cerebral palsy: The role of cocontraction of the rectus femoris and vastus lateralis. J Pediatr Orthop 1998;18:703-711.
Question 136
Topic: Physiology & Rehabilitation
A college football player performs bicep curls as part of his weight lifting routine. During the flexion phase of the curl, what term defines the type of muscle contraction?
Correct Answer & Explanation
. Eccentric
Explanation
Muscle contractions can be classified by tension, length, and velocity. Isometric contractions involve changing tension in the muscle while the muscle stays at a constant length. An example would be pushing against a wall. Isokinetic contractions occur when the muscle maximally contracts at a constant velocity. Isotonic contractions involve constant tension throughout the range of motion. Eccentric contraction is when the muscle lengthens during contraction. Eccentric contractions have the highest risk of injury. Plyometrics are eccentric contractions at a rapid rate. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 89-125.
Question 137
Topic: Physiology & Rehabilitation
A 28-year-old competitive weightlifter feels a sudden, sharp 'tearing' sensation in his anterior axilla while performing heavy bench presses. This is followed by immediate weakness, swelling, and extensive ecchymosis. Physical examination reveals a loss of the normal anterior axillary fold contour and pronounced weakness in internal rotation and adduction. Which specific portion of the pectoralis major muscle complex is most commonly ruptured in this classic mechanism of injury?
Correct Answer & Explanation
. Sternal head at or near the humeral insertion
Explanation
Pectoralis major ruptures almost exclusively occur in young, active males during eccentric contraction activities, most notoriously the bench press. The sternal (sternocostal) head undergoes maximal stretch and tension when the arm is extended and externally rotated, making it mechanically the most vulnerable to rupture. The injury most commonly occurs at the humeral insertion (tendon avulsion) or at the musculotendinous junction of the sternal head. The clavicular head is often spared.
Question 138
Topic: Physiology & Rehabilitation
During normal human gait, the muscles of the lower extremity exhibit highly coordinated, phased activity. Peak concentric contraction and maximal electromyographic (EMG) activity of the gastrocnemius-soleus complex occurs during which specific phase of the gait cycle?
Correct Answer & Explanation
. Terminal stance (Heel off)
Explanation
The gastrocnemius-soleus complex is crucial for ankle plantarflexion. During mid stance, the triceps surae contracts eccentrically to control the forward progression of the tibia over the fixed foot (controlling ankle dorsiflexion). Its peak electrical activity and maximal concentric contraction occur during terminal stance (heel off) to provide the active push-off required for forward propulsion, right before pre-swing.
Question 139
Topic: Physiology & Rehabilitation
A 32-year-old male felt a pop in his anterior axillary fold while bench pressing. Examination reveals loss of the anterior axillary contour and weakness in internal rotation. MRI shows rupture of the sternoclavicular head of the pectoralis major. What is the most common mechanism for this injury?
Correct Answer & Explanation
. Eccentric contraction with the shoulder extended and externally rotated
Explanation
Pectoralis major tendon ruptures classically occur during eccentric contraction with the arm extended and externally rotated. This places maximum tension on the sternoclavicular head, which is usually the first to fail during the eccentric phase of a bench press.
Question 140
Topic: Physiology & Rehabilitation
Local anesthetics primarily exert their action by blocking which specific ion channel in nerve cell membranes?
Correct Answer & Explanation
. Voltage-gated sodium channels
Explanation
Local anesthetics function by reversibly blocking nerve impulse conduction. Their primary mechanism of action involves binding to and inactivating voltage-gated sodium channels located on the inner surface of the neuronal cell membrane. By doing so, they prevent the rapid influx of sodium ions necessary for the depolarization phase of an action potential. This blockade inhibits the generation and propagation of nerve impulses, leading to a temporary loss of sensation in the region innervated by the affected nerves.
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