Muscle physiology 3

Question 1

what are the 2 ways to increase strength of a contraction?

Answer 1

1. More motor units (synchronization)
2. Increase frequency of stimulation to motor unit neuron

Question 2

_______ motor units recruited first, then _________ recruited

Answer 2

Slow-twitch/weak, fas-twitcht/strong

Question 3

______ twitch is not strong, but resistant to fatigue

Answer 3

Slow

Question 4

______ twitch is strong but fatigue easily

Answer 4

Fast

Question 5

Synchronous activation of motor units increases strength by _____ effect

Answer 5

additive

Question 6

_______ units are usually inhibited but can be activated in rare conditions

Answer 6

Largest/Very strong

Question 7

Nerve bundle is stimulated with _________________, and this recruits more and more motor units

Answer 7

increased amount of current

Question 8

______ means “same load/tension”. the weight on your muscles stays constant and this measures shortening. these type of exercises involve movement where weight isnt changing (squat, bench press, walking, swimming)

Answer 8

Isotonic

Question 9

In isotonic contraction, the ________ helps to stretch elastic properties of skeletal muscle

Answer 9

Latent period

Question 10

does muscle shortening occur during the latency period?

Answer 10

YES that’s what builds up tension. This period is due to elastic properties prior to you noticing the weight is moving

Question 11

does mass change in isotonic movements?

Answer 11

NO

Question 12

Work = (______)( ______)

Answer 12

(Force)(distance)

Question 13

if you move an object you are creating ______

Answer 13

work

Question 14

if you have the same amount of load, but double the amount moved, what happens to work? (EX: moving 10kg 1cm vs 2cm)

Answer 14

this doubles the work!
(10x1) vs (10x2)

Question 15

Same load = _____ tension = _____ force (but work can change dependent on distance)

Answer 15

same, same

Question 16

How can you increase the force needed to lift a heavier load?

Answer 16

Recruit more motor units.
If you recruit more → displacement is faster with same weight → more force

Question 17

Force = number of _________

Answer 17

crossbridges in parallel

Question 18

Force = (______)(_______)

Answer 18

mass, acceleration

Question 19

Mass doesn’t change in isotonic system, so if you ______ you produce MORE force

Answer 19

accelerate

Question 20

How would recruitment of more motor units affect speed of contraction?

Answer 20

it would increase the speed of contraction (increase units/same mass = inc force = inc acceleration)

Question 21

How can marathon runners keep running so long but sprinters are exhausted after a short length?

Answer 21

long distance runners use ~⅓ of max force while sprinters use up max force in small amount of time

Question 22

what are the Factors influencing force generation?

Answer 22

inertia, force/velocity relationship

Question 23

Object must be accelerated to overcome ________ for it to be moved, and movement continues after contraction because the moving object has _____

Answer 23

inertia

Question 24

More inertia to overcome = prolonged ______

Answer 24

latency period

Question 25

Relaxation following contraction for a bigger object = relaxation is _____ (slowed down or accelerated?)

Answer 25

accelerated

Question 26

when is there maximum velocity to move an object?

Answer 26

when theres no weight! (you can jump faster/higher holding nothing rather than holding 50lbs)

Question 27

Increasing the load ________ velocity of shortening

Answer 27

decreases

Question 28

Power = (_______)(______)

Answer 28

(force)(velocity)

Question 29

Velocity = (_______)/(________)

Answer 29

(distance)/(time)

Question 30

Faster object is moving = _____ power it has

Answer 30

more

Question 31

maximum power output is at _______ Fmax

Answer 31

1/3 (33%)

Question 32

______ muscle contraction is when muscle length does NOT change. it measures tension/force (tension produced but no displacement). Joints do not move

Answer 32

Isometric

Question 33

______ exercises are static, and contract your muscles without changing their length (think planks, wall-sits, anything that is static and not moving)

Answer 33

isometric

Question 34

do you stretch elastic properties during isometric exercises?

Answer 34

there is NO slack, so you don’t need to stretch elastic properties

Question 35

__________ is when you summate mechanical events which increases cross bridges which increases force produced

Answer 35

Wave summation

Question 36

More tension = _____ resistance

Answer 36

more

Question 37

how does latency period for isometric compare to isotonic?

Answer 37

Latency period for isometric is very small compared to isotonic.

Question 38

why is latency period for isometric so much shorter than isotonic?

Answer 38

-You don’t need to overcome inertia/build up tension, because elastic component is stretched out prior to the contraction
-Object does not move = no inertia to overcome = force buildup is rapid

Question 39

if weight doesn’t change but you move faster, you add more _____

Answer 39

force

Question 40

_______ must be stretched by muscle contraction prior to moving the bone

Answer 40

Series elastic

Question 41

______ system is useful to measure summation of contraction

Answer 41

isometric

Question 42

do electrical events have a refractory period? do mechanical events?

Answer 42

-Electrical events in nerve/muscle DO have refractory period
-Mechanical events do NOT have refractory period and will continue as long as Ca+ is there

Question 43

_____ occurs when all sarcomeres are contracting at once in recruited motor units

Answer 43

Tetanus

Question 44

Can you tetanize muscle groups at various tensions/weights?

Answer 44

yes! you still experience tetanus when you are holding up a pencil and when you are holding a 50lb weight. You recruit more motor units for heavier object