Biomechanics of Resistance Exercise

Question 1

Proximal attachment

Answer 1

Muscle origin; point closest to the center of the body

Question 2

Distal attachment

Answer 2

Muscle insertion; point farthest from the center of the body

Question 3

Agonist

Answer 3

Prime mover; muscle most directly involved in producing a movement

Question 4

Antagonist

Answer 4

A muscle that slows or stops a movement; may also assist in joint stabilization

Question 5

Synergist

Answer 5

Muscles that assist indirectly in a movement; may also help to stabilize the bone

Question 6

Advantage of a long lever

Answer 6

Smaller required muscle force

Question 7

Disadvantage of a long lever

Answer 7

Reduced movement speed

Question 8

Sagittal Plane

Answer 8

Divides body left to right; bicep curls

Question 9

Frontal Plane

Answer 9

Divides body front to back; lateral shoulder raise

Question 10

Transverse Plane

Answer 10

Divides body into upper and lower sections; internal and external rotation of the shoulder, hip, torso, etc

Question 11

Newton’s 2nd Law: Force =

Answer 11

Mass x acceleration

Question 12

Work Equation

Answer 12

Work = Force x Displacement (distance object travels)

Question 13

Power Equation

Answer 13

Power = Work/time

Question 14

What muscle action is indicated by negative (-) work or power

Answer 14

Eccentric muscle action; the weight being lifted is applying more force to the muscle than the muscle is applying to the weight

Question 15

Equation for rotational work around a joint

Answer 15

Rotational work = torque x angular displacement

Question 16

Biomechanical factors that affect strength

Answer 16

Neural control, muscle cross-sectional area, muscle fiber arrangement, muscle length, joint angle, muscle contraction velocity, joint angular velocity, and body size

Question 17

In what position does a muscle have the greatest force-generating potential?

Answer 17

Resting position; this is where the maximal number of crossbridge sites between actin and myosin are available

Question 18

What happens to the force capability of a muscle as the velocity of muscle contraction increases?

Answer 18

Force capability decreases

Question 19

Is strength-to-mass ratio usually higher in smaller or larger athletes?

Answer 19

Smaller athletes; increases in body size exceed increases in muscle cross sectional area (strength)

Question 20

When a weight is horizontally closer to a joint, it exerts more or less resistive torque?

Answer 20

Less torque

Question 21

When a weight is horizontally farther from a joint, it exerts more or less resistive torque?

Answer 21

More torque; bicep curl is hardest when elbow is at 90 and weight is in a straight horizontal line from elbow joint

Question 22

Inertial Force (Inertia) =

Answer 22

mass x acceleration

Question 23

Based on the principles of acceleration, is resistive force greater at the beginning of the movement or at the end range of motion?

Answer 23

Greater at the beginning range of motion; smaller at the end range of motion

Question 24

Bracketing Technique

Answer 24

Technique in which athlete performs the sport movement with both lower than normal and greater normal resistance

Question 25

How does the amount of muscular force required for a friction-based exercise change throughout the movement?

Answer 25

More force is required to initiate movement between 2 surfaces in contact than to maintain movement (the coefficient of static friction is always greater than the coefficient of sliding friction)

Question 26

Does friction resistance change as speed increases?

Answer 26

No (but power output does)

Question 27

When using fluid-resisted machines, what muscle actions do the agonist and antagonist muscles perform?

Answer 27

Both act concentrically (agonist acts concentrically to move the weight; antagonist acts concentrically to return the weight to its original position)

Question 28

85-90% of back injuries occur at which two spots in the vertebral column?

Answer 28

Between L4 and L5 and between L5 and S1

Question 29

Resistance training exercises involving the back should be performed with the back in which position to reduce injury?

Answer 29

A moderately arched position (lordotic) which is the natural neutral position of the spine.

Question 30

Kyphotic back position

Answer 30

Rounded back

Question 31

Recommendations for wearing a weight belt during lifts

Answer 31

1. A weight belt is not needed for exercises that do not directly affect the low back 2. Refrain from wearing a belt during lighter sets (to help develop necessary abdominal musculature) but may wear one for near-maximal and maximal sets 3. Belts are not needed if athlete takes the time to properly progress and build up abdominal/back muscle strength

Question 32

What are the 3 components of a lever?

Answer 32

1. Fulcrum (the pivot point) 2. Moment arm of the muscle force. This equals the distance from the muscle insertion point to the fulcrum 3. Moment arm of the resistive force (ex. dumbbell). This equals the distance from the position of the weight to the fulcrum.

Question 33

Mechanical advantage (or disadvantage) is determined by what?

Answer 33

The ratio of the moment arm of the resistive force to the moment arm of the muscle force

Question 34

Does a mechanical ratio of greater than 1.0 indicate mechanical advantage or disadvantage?

Answer 34

Mechanical advantage

Question 35

Does a mechanical ratio of less than 1.0 (ex. 1/2, 1/3, etc) indicate mechanical advantage or disadvantage?

Answer 35

Mechanical disadvantage

Question 36

Type of lever in which the muscle force and and resistive force act on opposite sides of the fulcrum

Answer 36

First class lever

Question 37

Example of first class lever

Answer 37

The forearm in elbow extension (tricep extension)

Question 38

Type of lever in which the muscle force and resistive force act on the same side of the fulcrum, with the muscle force having a longer moment arm than the resistive force (and thus a mechanical advantage)

Answer 38

Second class lever

Question 39

Example of second class lever

Answer 39

The foot in a heel raise

Question 40

Type of lever in which the muscle force and resistive force act on the same side of the fulcrum with the muscle force having a shorter moment arm than the resistive force (mechanical disadvantage)

Answer 40

Third class lever

Question 41

Example of a third class lever

Answer 41

The forearm in elbow flexion (bicep curl)

Question 42

How does the patella increase the mechanical advantage of the quadriceps muscle?

Answer 42

By increasing the distance of the quad tendon's insertion from the knee's axis of rotation (fulcrum)

Question 43

True or False: The mechanical advantage or the ratio of the moment arm of the resistive force to the moment arm of the muscle force changes throughout the movement

Answer 43

True; as the angle of movement changes so does the relative mechanical advantage