Deck 1: Biomechanics of Sports Injury

Question 1

From an epidemiology perspective the severity of an injury is defined by the amount of 'time lost'. What are the classifications of injury severity in terms of time lost?

A) Minor (one to seven days), moderately serious (eight to 21 days) or serious (21 or more days or permanent damage)
B) Minimal (24 - 48 hours), serious (72 hours - 8 days) or catastrophic (8 days +)
C) Minor (0 days), moderately serious (1-7 days), serious (8-21 days)
D) Grade I (1-7 days), Grade II (8-21 days), Grade III (6 weeks to 1 year)

Answer 1

A

Question 2

From a clinical perspective, injury severity is classified by the amount of structural involvement, physical signs, and extent of dysfunction. What are the classifications of ligament injury severity in a clinical model?

A) Minor (one to seven days), moderately serious (eight to 21 days) or serious (21 or more days or permanent damage)
B) Minimal (24 - 48 hours), serious (72 hours - 8 days) or catastrophic (8 days +)
C) Grade I (1-7 days), Grade II (8-21 days), Grade III (6 weeks to 1 year)
D) Grade I (mild fibre damage), Grade II (moderate fibre damage), Grade III (complete rupture of ligament)

Answer 2

D

Question 3

What is the definition of mechanism of injury?

A) The factors that put the athlete at risk of injury.
B) The physical process responsible for given damage to a body system.
C) The description of the inciting event.
D) The tissue response to mechanical loading.

Answer 3

B

Question 4

There are many different categorizations of injury mechanisms, which of the following have been proposed by Leadbetter (2001)?

A) Crushing deformation, Impulsive impact, Skeletal acceleration, Energy absorption and Extent & rate of tissue deformation.
B) Playing Situation, Athlete-opponent behaviour, Whole body biomechanics and Joint-tissue biomechanics.
C) Contact, Dynamic overload, Overuse, Structural vulnerability, Inflexibility, Impact and Rapid Growth.
D) A description of inciting event, Description of mechanical factors and Tissue responses to mechanical factors.

Question 5

Epidemiology is the study of the incidence, distribution and determinants of disease and injury frequency within a given population (Woodward, 2005) Descriptive epidemiology provides the what, the who, the when and the where, by studying what?

A) The causal relationships for injury.
B) The relationships between injury occurrence and certain risk factors.
C) The frequency and cause of injury.
D) The frequency, or incidence and prevalence of injury occurrence.

Question 6

What is a risk factor for injury?

A) The factors that put the athlete at risk of injury.
B) The tissue response to mechanical loading.
C) Something that increases your probability of experiencing an injury.
D) The physical process responsible for given damage to a body system.

Question 7

Risk factors may be categorized as intrinsic or extrinsic to the athlete. Extrinsic risk factors are

A) those that relate to the sporting environment
B) related to equipment, climate, opponent skill or ability and rules of the game
C) those factors that increase the athletes susceptibility to injury
D) all of the above

Question 8

A biomechanist uses the principles and theories of the disciplines of physics and mechanical engineering to describe the forces and force-related (mechanical) factors that lead to injury. In the biomechanical model what relationships determine the outcome of the inciting event?

A) The factors that put the athlete at risk of injury.
B) The relationships between injury occurrence and certain risk factors.
C) The relationship between load applied and load tolerance.
D) None of the above.

Question 9

The critical feature for mechanical factors is that they must explain how the inciting event either resulted in a mechanical load in excess of that tolerated under normal circumstances or reduced the tolerance levels to a point at which a normal mechanical load cannot be tolerated (Fung, 1993) The mechanical factors may differ for each tissue and are dependent on

A) the nature and type of load
B) the load rate, the frequency of load repetition, the magnitude of energy transfer
C) the intrinsic factors such as age, sex and physical condition
D) All of the above.

Question 10

Energy has been referred to as the primary agent of injury and, as such, is one of the most critical biomechanical concepts related to sports injury (Whiting and Zernicke, 2008) Which of the following statements regarding mechanical energy is (are) true?

A) Mechanical energy is the form most commonly related to sports injury.
B) Mechanical energy is measured in joules (J)
C) The mechanical energy of a body can be classified according to the energy of its motion or the energy related to its position.
D) All of the above.

Question 11

Gravitational potential energy refers to?

A) The potential of a body to do work as a function of its height with respect to a reference surface.
B) The potential of gravity to do work.
C) The potential of a body to store energy by virtue of its deformation.
D) The kinetic energy related to the linear acceleration of a body.

Question 12

What does the principle of conservation of energy indicate for the net work done on a system?

A) Energy is never lost.
B) Energy cannot pass from one system to another during a collision.
C) The net work done on a system is converted into kinetic and potential energy such that the total energy of the system remains constant throughout the motion.
D) The net work done on a system is converted into kinetic and potential energy such that the total energy of the system remains constant throughout the motion, only when there are no external forces acting on the system.

Question 13

Transfer of energy is the mechanism by which energy is passed from one body to another. Which of the following is an example of energy transfer in sport?

A) A diver stands at the end of the platform in preparation for a dive.
B) A diver depresses the springboard in preparation for a dive.
C) A diver swings their arms back and forth in preparation for a dive.
D) b and c above.

Question 14

Three uni-directional load types are?

A) Comprehension, Tensile and Shear.
B) Compressive, Tensile and Parallel.
C) Compressive, Stretching and Shear.
D) Compressive, Tensile and Shear.

Question 15

When a load is applied to a body, that body may accelerate or the body may change in shape or configuration. Which of the following statements regarding load deformation are true?

A) Deformation is measured in relative terms, thus is dimensionless.
B) Deformation is measured in absolute terms, for example mm.
C) We can depict the load-deformation relationship graphically in a stress-strain curve.
D) The relationship between load and deformation is not unique to the tissue or material type being loaded.

Question 16

Which of the following statements regarding stress are false?

A) The standard (SI) unit of stress is the pascal (Pa), defined a 1 N distributed over 1 cm2.
B) When bonds have been deformed, they try to restore themselves to their original positions, developing an internal resistance called stress.
C) The stress (σ) is dependent upon the material properties of the tissue, the magnitude of the load and the cross sectional area of tissue to which the load is applied.
D) The stresses in a material are known as the normal stresses when they are defined perpendicular to the relevant cross-section of the material.

Question 17

Three principle stresses are: tensile, compressive and shear. What are the non principle stresses commonly experienced in sport?

A) Rotation and sliding
B) Torsion and sliding
C) Rotation and bending
D) Torsion and bending

Question 18

Bending is best illustrated in terms of a cantilever beam, when bent, the material on the concave surface of the beam experiences ____________ stress while the material on the convex surface experiences ___________ stress.

A) torsion and bending
B) bending and tensile
C) compression and tensile
D) tensile and compression

Question 19

Bending is best illustrated in terms of a cantilever beam. What is the 'neutral axis' of the beam?

A) An axis between the two surfaces that experiences the greatest deformation and stress.
B) An axis between the two surfaces that experiences the greatest deformation and strain.
C) An axis between the two surfaces that experiences the least deformation and strain.
D) An axis between the two surfaces that experiences the no deformation and no stress.

Question 20

The forces acting on the cantilevered beam (Figure 1.5(a) in the text) create a moment on the beam, the bending moment (Mb) Which of the following statements regarding the calculation of bending moment on the beam are false?

A) For such a beam, the bending moment at any section (e.g. xs, xs) is equal to the force applied to the beam (F) multiplied by the distance of its point of application from that section (x)
B) The bending moment (M) will increase proportionally from zero at F to a value of FL at the base of the beam.
C) The bending moment (M) will increase proportionally from zero at FL to a value of F at the base of the beam.
D) The bending moment (M) will vary along the length of the beam.

Question 21

The second moment of area is?

A) Sometimes known as the 'area moment of inertia'.
B) Is a property of a cross section that can be used to predict the resistance to bending and deflection about the neutral axis.
C) Dependent upon the cross-sectional shape of the structure.
D) All of the above.

Question 22

The polar second moment of area is?

A) The resistance to torsional load about the long axis of a cylinder.
B) Is a property of a cross section that can be used to predict the resistance to bending and deflection about the neutral axis.
C) Is inversely proportional to the radial distance from the neutral axis.
D) Is equivalent to the moment of inertia of the rod.

Question 23

Strain (ε) is defined as?

A) σ = δr/r, Where δr is the change in a specific dimension of the material, with an original value of r.
B) A relative measure of deformation within a tissue or structure in response to externally applied loads.
C) A non-dimensional parameter usually expressed as a percentage.
D) The relationship between stress and strain can be visualised by plotting stress as a function of strain.

Question 24

The relationship between stress and strain can be visualised by plotting stress as a function of strain (Figure 1.7 in the text) The stress-strain (σ-ε) ratio, the ratio of the stress to the strain in that region for a particular load type, provides a numerical value of what?

A) the compliance modulus
B) the shear modulus
C) the elastic modulus
D) the compressive modulus

Question 25

Linear materials operate according to Hooke's Law, which means that ____________.

A) stress and strain are non-linearly related such that resulting strain is proportional to the developed stress
B) they do not experience energy loss once a load is removed from the material
C) once a load is removed from the material a permanent set remains because the material has entered the region of plastic deformation
D) where stress and strain are linearly related such that the resulting strain is inversely proportional to the developed stress

Question 26

Biological materials are viscoelastic, what does this mean?

A) That throughout their physiological range the mechanical response of most biological tissues is not entirely linear.
B) Once a load is removed from the material or tissue it will return to its original shape, much like a rubber band.
C) That biological tissues have a non-linear characteristics created by the tissue's fluid component.
D) Both a and c are correct.

Question 27

The term 'hysteresis' refers to?

A) The differences in the load-deflection curve for loading and unloading.
B) The energy loss proportional to the gray shaded area under the stress-strain curve (Figure 1.7(b))
C) The 'permanent set' that remains when a material has enters the region of plastic deformation.
D) All of the above.

Question 28

Strain energy is stored in any deformed material during deformation. Which of the following statements regarding strain energy are true?

A) Elastic strain energy is strain energy that is recoverable while plastic strain energy is strain energy that is lost.
B) All of the above.
C) The area under the stress-strain curve up to any chosen strain is a measure of strain energy.
D) Strain energy is stored in any deformed material during deformation, as in a trampoline bed, vaulting pole, shoe sole, protective equipment, or compressed ball.

Question 29

One of the major differences between biological materials and non-biological materials is how load affects them over time. What is this time dependent behaviour is called?

A) Hook's Law
B) Viscoelasticity
C) Hysteresis
D) Resilience

Question 30

In a biological material the measured strain is a function of stress, time and temperature. When a material deforms as a function of time under a constant load, we call this phenomenon _______.

A) stress-relaxation
B) viscoelastic
C) creep
D) hysteresis

Question 31

In a biological material the measured strain is a function of stress, time and temperature. When a material undergoing a constant strain will begin to relax, we call this phenomenon

A) stress-relaxation
B) viscoelastic
C) creep
D) hysteresis

Question 32

The mechanical properties of most biological material are directionally dependent which means their mechanical properties depend on the direction in which they are loaded. What is the mechanical term that used to describe this Phenomenon?

A) Isotrophy
B) Anisotrophy
C) Homogeneity
D) Non-homogeneous

Question 33

Cortical bone is a non-homogeneous, anisotropic, viscoelastic, brittle material which is weakest when loaded in __________.

A) compression
B) shear
C) tension
D) bending

Question 34

The overall structure of long bones gives an optimal strength-to-weight ratio. How is this achieved?

A) The cancellous component helps to prevent the cortical component from cracking while the cortical component helps prevent the cancellous one from yielding.
B) The cortical component helps to prevent the cancellous component from cracking while the cancellous component helps prevent the cortical one from yielding.
C) The trabeculae are more densely packed in those parts of the bone that have to transmit the greatest stress.
D) The orientation of the trabeculae corresponds to the direction of tensile and compressive stresses and is roughly orthogonal.

Question 35

Bone is a viscoelastic material; thus, rate of loading is important to its biomechanical behaviour. What happens to bone when loaded at higher rates?

A) It becomes less stiff.
B) It has a greater elastic modulus.
C) It sustains a lower load to failure.
D) All of the above.

Question 36

Which of the following statements regarding the biomechanical properties of cartilage is correct?

A) The deformation of cartilage helps to increase the joint contact area and decrease range of motion at the joint.
B) It has an elastic modulus in compression that decreases with increasing depth from the cartilage surface because of the collagen fibre orientation.
C) The compressive modulus decreases with load as the cartilage is compressed and the chondromes resist the load.
D) After the load is removed, cartilage returns to its initial elasticity within a relatively short time providing that the load was of short enough duration and low enough magnitude.

Question 37

Total tension in a muscle is dependent on the tension length characteristics of both the active and passive components of muscle. Which of the following statements regarding active tension in a muscle are correct?

A) Active tension developed in a skeletal muscle is proportional to the total number of cross-bridges in parallel.
B) Active tension is at its maximum at resting length.
C) As the muscle lengthens past resting length active tension begins to build in the connective tissue.
D) As the muscle continues to lengthen there is an increase in the active tension as well as an increase in the rate of development of active tension.

Question 38

What are the three fundamental conditions of an effective stretch-shorten cycle (in order)?

A) First, a short and fast eccentric phase; second, a well timed preactivation of the muscles before the eccentric phase; third, an immediate transition between eccentric and concentric phases.
B) First, a well timed preactivation of the muscles before the eccentric phase; second, a short and fast eccentric phase; third, an immediate transition between eccentric and concentric phases.
C) First, a short and fast eccentric phase; second, an immediate transition between eccentric and concentric phases; third, a well timed preactivation of the muscles before the eccentric phase.
D) First, an immediate transition between eccentric and concentric phases; second, a short and fast eccentric phase; third, a well timed preactivation of the muscles before the eccentric phase.

Question 39

Because of their non-linear tensile properties (Figure 1.18), ligaments offer early and increasing resistance to tensile loading over a narrow range of joint motion. Which of the following statements most appropriately describes the practical implications of this phenomenon?

A) At higher forces, ligaments become stiffer and provide more resistance to developing deformations.
B) This means that when the joint is displaced towards the outer limit of movement, collagen fibres are recruited from the crimped state to become straightened, which increases the resistance and stabilizes the joint.
C) Daily activities, such as walking and jogging, are usually in the toe of the stress-strain curve (Figure 1.18) and strenuous activities such as landing, jumping and cutting are normally in the early part of the linear region.
D) All of the above.

Question 40

Which of the following statements regarding the mechanical properties of tendon are false?

A) As well as having a relatively high tensile strength and stiffness, tendon is resilient, having a relative hysteresis of only 2.5-10%.
B) When the tendon compliance is high, the change in muscle fibre length will be small compared to the length change of the whole muscle-tendon unit.
C) Within the physiological range, a tendon has limited viscoelastic behaviour for a biological material.
D) Due to its viscoelastic behaviour, energy storage is likely to be limited even when the tendon is subject to large forces.