Chapter 2

Question 1

Biomechanics

Answer 1

The mechanisms through which components interact to create movement

Question 2

Origin and insertion

Answer 2

Origin is proximal (more stable)
Insertion is distal

Question 3

Describe agonist

Answer 3

The prime mover

Question 4

Describe antagonist

Answer 4

The muscle that works against the prime mover. Slows down and stops the movement

Question 5

Describe synergist

Answer 5

The muscle that assist indirectly with the movement. Acts as a stabilizer

Question 6

What is a lever?

Answer 6

A rigid or semirigid body that, when subjected to force, exerts force on any object

Question 7

First class lever

Answer 7

The applied force and resistive force sit on opposite sides of the fulcrum
(i.e. tricep extensions)

Question 8

Type 2 lever

Answer 8

The resistive and muscle force act on the same side of the fulcrum. With the muscle force having a longer moment arm, thus creating a mechanical advantage
(i.e. calf raises)

Question 9

Type 3 lever

Answer 9

When the resistive force and muscle force act on the same side of the fulcrum with the MA of the resistive force being longer. Thus creating a mechanical disadvantage
(i.e. bicep curl)

Question 10

Mechanical Advantage definition

Answer 10

The ratio of the moment arm of the applied force and resistive force

Question 11

Mechanical advantage ratio

Answer 11

Greater than 1.0. The muscle force can apply less force than the resistive force to produce an equal amount of torque

Question 12

Mechanical disadvantage ratio

Answer 12

Less that 1.0. The muscle force has to apply greater force than the resistive force to produce an equal amount of torque.

Question 13

How does the patella affect mechanical advantage?

Answer 13

Mechanical advantage can vary through ROM motion. During knee extension the patella maintains the distance of the quadriceps tendon from the axis of rotation thus increasing the mechanical advantage

Question 14

How does mechanical advantage vary during a bicep curl?

Answer 14

The elbow does not have a “patella” the distance from the joint to the tendon vary throughout moving. Changing the mechanical advantage.
Additionally, as the weight is lifted the MA of the resistive force changes, affecting the mechanical advantage

Question 15

Tendon insertion and Mechanical advantage

Answer 15

The point where the tendon attaches to the bone can vary
-further from joint = greater mechanical advantage but loss of maximum speed
(able to lift heavier weights but not as fast)
This arrangement also reduces force capabilities during faster movements

Question 16

What are the 3 planes of motion?

Answer 16

Sagittal, frontal, and transverse

Question 17

Define Force and its SI units

Answer 17

F= M * A
(Newtons)

Question 18

Define strength

Answer 18

The capacity to exert force at any given speed

Question 19

Define acceleration

Answer 19

The change in velocity per unit of time

Question 20

Define Power and its SI units

Answer 20

P= W/T
or
P = F* Velocity
(Watts)

Question 21

Define work and its SI units

Answer 21

W = F * Displacement
(Joules)

Question 22

What is negative work?

Answer 22

Work performed on, rather than by, the muscle
(occurs during eccentric movements)

Question 23

Describe Angular displacement

Answer 23

The angle through which an object rotates

Question 24

Rotational work

Answer 24

Rotational work = Torque X angular displacement

Question 25

List the biomechanical factors of human strength

Answer 25

-Neural control
-muscle cross-sectional area
-arrangement of muscle fibers
-muscle length
-joint angle
-muscle contraction velocity
-joint angular velocity
-strength to mass ratio
-body mass

Question 26

Neural control and strength

Answer 26

Rate coding: the rate at which MU fire
Recruitment: which and how many MUs fired

Question 27

Arrangement of muscle fibers and strength

Answer 27

Angle of pennation: the angle between the muscle fibers and an imaginary line between the muscle origin and insertion
The more pennation = more cross sectional area and greater force production

Question 28

Muscle length and strength

Answer 28

Resting vs contraction vs stretched
The amount of cross bridge site available determine the muscle ability to generate force.
Resting is optimal

Question 29

The 3 types of muscle actions

Answer 29

Concentric
Eccentric
Isometric

Question 30

Body size and strength

Answer 30

Body size incerases faster that muscle strength. Smaller athletes tend to have greater strength to mass ratio

Question 31

Sources of resistance

Answer 31

-gravity
- inertia
-friction
- fluid resistance
-elasticity

Question 32

Back injury

Answer 32

back should be moderately arched. Vulnerable due to compression and large MA in some movements

Question 33

Intra-abdominal pressure and lifting belts

Answer 33

the “fluid ball” aids in supporting the vertebral column

Question 34

Shoulder injury

Answer 34

Prone to injury of stabilizing muscles and tendons because of the shallow joint.

Question 35

Knee injury

Answer 35

Prone to injury because of its location between two levers

Question 36

Elbows and wrists

Answer 36

Primary concerns involves overhead lifts