Biomechanics Chapter 6
Which of the following statements is/are true? a. Pennate muscles are capable of producing more tension per unit of cross-sectional area than parallel muscles. b. Parallel muscles are capable of producing more range of motion than pennate muscles. c. Both A and B are true. d. Neither A nor B is true.
Both A and B are true.
Which of the following is a behavioral property of muscle tissue? a. contractility b. extensibility c. elasticity d. excitability or irritability e. all of the above
all of the above
Which of the following is/are characteristic(s) of muscle fatigue? a. reduction in muscle force b. reduction in shortening velocity c. prolonged relaxation of motor units between recruitment d. all of the above
all of the above
During the down phase of a knee extension exercise, what role does the hamstring group play? a. neutralizer b. stabilizer c. antagonist d. agonist
antagonist
Which of the following is a potential disadvantage of multijoint muscles? a. active insufficiency b. passive insufficiency c. both A and B d. none of the above
both A and B
Which of the following is true regarding the parallel elastic component (PEC) of muscular elasticity? a. This component is provided by the muscle membranes. b. This component provides resistance when a muscle is passively stretched. c. This is the component primarily responsible for the elasticity of muscle. d. both A and B
both A and B
Which of the following is true regarding the stretch-shortening cycle (SSC)? a. When a muscle is stretched just prior to contraction, the resulting contraction is more forceful. b. An eccentric contraction is followed by a concentric contraction. c. The SSC promotes storage of elastic energy. d. both A and B e. all of the above
both A and B
Which of the following likely contributes to the stretch-shortening cycle? a. the series elastic component b. muscle spindle activity c. both A and B d. none of the above
both A and B
During the kicking and follow-through phases of a punt, the quads are experiencing what type of contraction? a. isometric b. isokinetic c. eccentric d. concentric
concentric
Which of the following statements represents the force-velocity relationship for muscle tissue? a. contraction is slower when the load is heavier b. the speed of contraction is not affected by the nature of the load c. contraction is slower when the load is lighter d. contraction is faster when the load is heavier
contraction is slower when the load is heavier
What type of muscle contraction is employed by the elbow flexors when slowly lowering your backpack to your desk? a. isometric b. isokinetic c. eccentric d. concentric
eccentric
When an opposing torque at a joint is greater than the torque created by a muscle, what type of contraction occurs in that muscle? a. isometric b. isotonic c. eccentric d. concentric
eccentric
Which of the following types of muscle tension is commonly used as a braking mechanism to slow limb movement? a. eccentric b. concentric c. isotonic d. isometric
eccentric
Which of the following types of strength training is particularly associated with subsequent muscular soreness? a. isometric b. all of the above c. eccentric d. concentric
eccentric
Which behavioral property of muscle tissue is defined as "the ability to respond to a stimulus"? Hint: Just the ability - not the response of that ability. a. irritability b. extensibility c. elasticity d. contractility
irritability
A contraction in which there is not a change in length is called what? a. isometric b. dynamic c. concentric d. isokinetic
isometric
A muscle contraction which does not result in a change in length is called
isometric
In human skeletal muscle, force generation capability is highest in which of the following conditions? a. muscle is slightly shortened under tension b. muscle length is irrelevant to force production c. muscle is at resting length under tension d. muscle is slightly lengthened under tension
muscle is slightly lengthened under tension
Which of the following terms best describes the rate of torque production at a joint? Think work/time. a. muscular strength b. muscular power c. mechanical work d. muscular energy output
muscular power
The amount of torque a muscle group can generate at a joint is used to measure what? a. muscular flexibility b.muscular strength c. muscular endurance d. muscular power
muscular strength
When flexing the elbow, the biceps brachii, brachioradialis, and brachialis are the three major agonists recruited to perform this movement (all perform flexion at the elbow). However, the biceps brachii also causes supination, an undesired movement. Therefore another muscle acting as a ________, causing ________ must be recruited to prevent the undesired motion. a. neutralizer; pronation b. neutralizer; extension c. stabilizer; pronation d. stabilizer; extension
neutralizer; pronation
The _____________ fiber arrangement is a pattern of fibers within a muscle with short fibers attaching to one or more tendons.
pennate
The A.V. Hill model has three components that act together to describe the behavior of whole muscle. Where is the series elastic component (SEC) of a muscle found? a. tendon b. ligament c. muscular fascia d. all of the above
tendon
During the execution of a pull-up when the chin is over the bar, which force exerted by the biceps brachii is greatest at the elbow? a. the "pinching" force b. the dislocating force c. the stabilizing force d. the rotary force
the dislocating force
The elasticity of human skeletal muscle tissue is believed to be due primarily to which of the following? a. the active elastic component b. the parallel elastic component c. the series elastic component d. the continuous elastic component
the series elastic component
Which of the following time periods is termed electromechanical delay? In motor control research, this may be referred as, "motor reaction time". a. the time required for a muscle to reach peak tension after the development of tension is initiated b. the time required for conduction of the nerve impulse to the neuromuscular junction c. the time required for the nerve impulse to cross the neuromuscular junction d. the time required for the muscle to initiate the development of tension after receipt of the nerve impulse
the time required for the muscle to initiate the development of tension after receipt of the nerve impulse
The torque of a muscle (rotary component) is greatest in what position? a. position does not affect torque b. when the muscle insertion is 90° to the bone c. when the moment arm is shortest d. when the moment arm is longest
when the muscle insertion is 90° to the bone
Which of the following statements is/are true? a. The origin is the attachment that is closest to the middle of the body b. The muscle's origin is usually broader than the insertion. c. The attachment that is distal (i.e. father from midline) is the insertion. d. The muscle's insertion is usually narrower than the origin. e. All of the above are true.
All of the above are true.
Which of the following is/are characteristic of fast-twitch oxidative glycolytic fibers? a. Contraction speed is intermediate (faster than type I but slower than type IIB). b. Fatigue rate is intermediate (faster than type I but slower than type IIB). c. both A and B d. none of the above
Fatigue rate is intermediate (faster than type I but slower than type IIB).
List and describe four common muscle injuries.
Four common muscle injuries include strains, contusions, cramps, and delayed-oneset muscle soreness. Strains can result from overstretching of muscle tissue. Most typically an active muscle is overloaded with the magnitude of the injury related to the size of the overload and the rate of overloading. Strains can range from mild to severe. Contusions are muscle bruises cause by compressive forces sustained during impacted. These can also consist of hematomas within the muscle tissue. Cramps can derive from electrolyte imbalance, deficiencies in calcium and magnesium, or even dehydration. Cramps can also occur as secondary to direct impacts. These may also involve moderate to severe muscle spasms, with proportional levels of accompanying pain. Lastly, delayed-onset muscle soreness arises 24-72 hours after participation in a long or strenuous bout of exercise and is characterized by pain, swelling, and the same kinds of histological changes that accompany acute inflammation.
Explain at least four roles assumed by muscles.
One role that is assumed by muscles involves stabilizing a portion of the body against a particular force. The force may be internal, from tension in other muscles or even external as provided by the weight of an object being lifted. There are stabilizers which role is played by a muscle acting to stabilize a body part against some other type of force. Another assumed role is a neutralizer. Neutrailizers prevent unwanted accessory actions that occur when agonists develop concentric tension. For example, if a muscle causes both flexion and abduction at a joint but only flexion is desired the action of the neutralizer causes adduction to eliminated the unwanted abduction. Neutralizers role is to eliminate an unwanted action produced by agonist. Muscles can also be agonist or primary movers. In a knee extension the quad are the agonists while the hamstrings are the antagonists or the opposers.
List and explain the behavioral characteristics of the musculotendinous unit, including similarities and differences to other tissue.
The characteristics of the musculotendinous unit include extensibility, elasticity, irritability, and the ability to develop tension. Extensibility is the ability to be stretched or to increase in length. Elasticity is the ability to return to the normal size after being stretched. Muscle elasticity also provides for a smooth transition of tension from muscle to bone. Irritability is the ability to respond to a stimulus. Stimuli affecting muscles are either electrochemical, such as an external blow. When activated by stimuli, the muscle responds by developing tension. The ability to develop tension is unique to muscle tissue. It has also been referred to as the contractile component of muscle function. Contractility is the ability to shorten in length.
Which of the following is an example of active insufficiency? a.The finger flexors cannot generate maximum grip force when they are shortened during an accompanying wrist flexion b. The prevention of full knee extension by a tight or immobile hamstring c. Neither of the above d. Both of the above
The finger flexors cannot generate maximum grip force when they are shortened during an accompanying wrist flexion
(T/F) In concentric muscle action, velocity increases at the expense of a decrease in force and vice versa.
True
(T/F) Muscle fibers are typically recruited according to the size principle (i.e. smallest motor units first).
True
Which of the following most accurately describes a motor unit? a. a single muscle fiber and a single motor neuron b. a single motor neuron and all muscle fibers it innervates c. a single muscle fiber and several motor neurons d. none of the above
a single motor neuron and all muscle fibers it innervates
A muscle directly involved in causing a segment to move is called what (i.e. prime mover)? a. stabilizer b. neutralizer c. agonist d. antagonist
agonist
Which type of muscle could serve as an antagonist of a flexor? a. rotator b. abductor c. extensor d. adductor
extensor
A single muscle cell is called what? a. neuron b. unit c. bundle d. fiber
fiber
Which of the following does not characterize a pennate muscle? a. relatively strong b. fibers parallel to long axis of muscle c. relatively low range of motion d. all of the above are true
fibers parallel to long axis of muscle
Explain muscular strength. How is it measured? How does it change at different points during range of motion?
he most direct assessment of muscular strength commonly practiced is a measurement of the maximum torque generated by an entire muscle group at a joint. Muscular strength is then measured as a function of the collective force-generating capibility of a given functional muscle group. More specifically muscular strength is the ability of a given muscle group to generate torque at a particular joint. Using the bicep as an example, muscular strength is at its maximum when the muscle is oriented at 90 degrees to the bone, with change in angle the orientation in either direction progressively diminishing it.
During the first 12 weeks of resistance training, strength gains are classically attributed to what? a. improved innervation of the muscle b. increase in cross-sectional area c. both A and B d. none of the above
improved innervation of the muscle
Muscle hypertrophy in humans is primarily due to what? a. increase in number of muscle fibers b. increase in size of muscle fibers c. both A and B d. none of the above
increase in size of muscle fibers
A ______________ muscle fiber reaches peak tension relatively slowly.
slow-twitch
_______________ is a role played by a muscle to stabilize a body part against some other force.
stabilizer
he component force which is parallel to the moving bone and acts to pull the bones together at the joint is called what? a. rotary force b. stabilizing force c.curvilinear force d. dislocating force
stabilizing force
In which of the following activities do the biceps brachii function as antagonists? a. curling a barbell from the waist to shoulder height b. straightening the elbow during a pull-up c. none of the above d. straightening the elbow during a push-up
straightening the elbow during a push-up
A pattern of eccentric contraction followed immediately by concentric contraction is called ________________ cycle
stretch-shortening
