Phys of Ex Lab Exam 2 Lab 9

Your subject is an 22 year old female who weighs 139 lbs. You previously determined that her maximal voluntary contraction force was 35 lbs and her iEMG integral during the MVC was 0.000118. During lab today you had her hold a 21 pound weight isometrically for a few seconds and her integral during this lift was 0.000040. What is her normalized iEMG activity for this lift?

33.89%

Your subject is an 21 year old male who weighs 164 lbs. You previously determined that his maximal voluntary contraction force was 39 lbs and his iEMG integral during the MVC was 0.000108. During lab today you had him hold a 10 pound weight isometrically for a few seconds and his integral during this lift was 0.000060. What is his normalized iEMG activity for this lift?

55.6

Your subject is an 23 year old female who weighs 188 lbs. You previously determined that her maximal voluntary contraction force was 30 lbs and her iEMG integral during the MVC was 0.000271. During lab today you had her hold a 16 pound weight isometrically for a few seconds and her integral during this lift was 0.000166. What is her normalized iEMG activity for this lift?

61.3

Which of the following would have the least EMG activity when using a 15 lb weight? a. isometric action with high force arm:resistance arm ratio b. they would all be about the same c. isometric action with low force arm:resistance arm ratio d. concentric action with low force arm:resistance arm ratio

A

Which of the following would have the highest EMG integral with a 20 pound weight at mid flexion (~90degrees)? a. isometric action with good overlap of actin and myosin b. concentric action with poor overlap of actin and myosin c. concentric action with good overlap of actin and myosin d. they would all be about the same

B

Which of the following would have the highest EMG integral with a 20 pound weight? a. they would all be about the same b. concentric action with low force arm:resistance arm ratio c. concentric action with high force arm:resistance arm ratio d. isometric action with low force arm:resistance arm ratio

B

Which of the following would produce the least force? a. concentric bicep curl 30 deg /sec b. concentric bicep curl 300 deg /sec c. they would all be about the same d. concentric bicep curl 180 deg /sec

B

Which of the following would require the least number of motor units to be recruited when using a 15 lb weight? a. concentric action with low force arm:resistance arm ratio b. isometric action with high force arm:resistance arm ratio c. isometric action with low force arm:resistance arm ratio d. they would all be about the same

B

___________________________________ is a strategy the nervous system employs to reduce the likelihood of fatigue by alternating which motor units are being used. a. size principle b. asyncrhonous motor unit recruitment c. tetanus d. twitch summation e. multiple motor unit summation

B

Which of the following changes would cause the smallest increase in Torque? a. knee flexors going from 30 deg/sec to 300 deg/sec b. knee extensors going from 300 deg/sec to 30 deg/sec c. knee flexors going from 300 deg/sec to 30 deg/sec d. they would all be about the same

C

Which of the following changes would cause the smallest increase in Torque? a. they would all be about the same b. knee extensors going from 300 deg/sec to 30 deg/sec c. knee flexors going from 300 deg/sec to 30 deg/sec d. knee flexors going from 30 deg/sec to 300 deg/sec

C

Which of the following would have the lowest EMG activity with a 20 pound weight at mid flexion (~90degrees)? a. they would all be about the same b. concentric action with good overlap of actin and myosin c. isometric action with good overlap of actin and myosin d. isometric action with poor overlap of actin and myosin

C

Which of the following changes would cause the biggest decrease in Torque using concentric actions? a. knee extensors going from 300 deg/sec to 30 deg/sec b. knee flexors going from 30 deg/sec to 300 deg/sec c. they would all be about the same d. knee extensors going from 30 deg/sec to 300 deg/sec

D

Which of the following isokinetic actions would have the lowest EMG integral? a. knee extensors 300 degrees/second b. knee extensors 30 degrees/second c. knee extensors 180 degrees/second d. they would all be about the same

D

Which of the following would have the highest EMG integral with a 15 lb weight? a. isometric bicep curl 0 deg/sec b. they would all be about the same c. eccentric bicep curl 30deg/sec d. concentric bicep curl 30 deg/sec

D

Which of the following would produce the greatest force? a. concentric bicep curl 300 deg/sec b. concentric bicep curl 180 deg/sec c. they would all be about the same d. concentric bicep curl 30deg/sec

D

Which of the following would produce the least force? a. isometric bicep curl 0 deg/ec b. they would all be about the same c. eccentric bicep curl 30deg/sec d. concentric bicep curl 30deg/sec

D

The torque curve on the far left was recorded from a muscle group during a single concentric isokinetic action. You then recorded the EMG of this same muscle group using free weights during a single concentric action. Which of the figures best depicts the EMG tracing we would observe for this muscle during this lift? - Arch from 90 to 180

EMG - upside down arch

Which of the following EMG tracings best depicts the electrical activity of a muscle group that has its sticking point at 180 ?

EMG increase from 90 to 180

Which of the following EMG tracings best depicts the electrical activity of a muscle group moving a 25 pound weight and has a very very good overlap of actin and myosin at 135 ?

Graph that is a a V - least EMG activity at the best leverage

Which of the following fiber types would tend to be recruited first? IIAX IIX IIC I IIA

I

Which of the following fiber types would tend to be recruited first? IIC IIAX IIA IIX I

I

Which of the following fiber types would tend to have the greatest succinate dehydrogenase activity? (SDH catalyzes a step in the citric acid cycle)

I

Which of the following fiber types would tend to be the largest diameter fibers in men? IIA IIC IIAX IIX I

IIA

Myosin heavy chain IIA and Myosin heavy chain IIX would both be found in which fiber type?

IIAX

Which of the following fiber types would tend to have the highest PFK (phosphofructokinase) activity?

IIX

Which of the following fiber types would tend to have the least succinate dehydrogenase activity? (SDH catalyzes a step in the citric acid cycle)

IIX

Which of the following fiber types would tend to store the most glycogen? IIX IIC IIA I IIAX

IIX

In our recent lab we did experiments related to several aspects of muscle performance including force, velocity, power, and muscle length. Which of the following figures best depicts the length-total tension curve?

Increase, Small Dip, Increase Again

Which of the following torque curves best depicts the expected torque curve for an extensor muscle group?

Right Side Up Arch from 90 to 180

Which of the following torque curves best depicts the expected torque curve for a flexor muscle group?

Right Side Up Arch, flat on top from 90 to 180

___________________________________ is related to the orderly recruitment of motor units from lowest threshold to highest threshold

Size Principle

In our recent lab we did experiments related to several aspects of muscle performance including force, velocity, power, and muscle length. Which of the following figures best depicts the length-active tension curve?

Slanted Right Side Up Arch

The EMG tracing on the far left was recorded from a muscle group during a single concentric action with free weights. You then tested this same muscle group on an isokinetic dynamometer. Which of the figures best depicts the torque curve we would observe for this muscle during this isokinetic action? - Description: EMG looks like a arch

Torque curve will be the inverse

The far left panel depicts the torque curve for a muscle group performing an eccentric action. Which of the other curves best represents the torque curve you would expect to see for this same muscle group during a concentric action? Description - upright arch with small plateau

Upright Arch with Small Plateau but just shorter

Which of the following EMG tracings best depicts the electrical activity of a muscle group with the best leverage at 135 while performing a knee extension with free weights?

V Shape - lowest EMG activity at the best leverage

Which of the following EMG tracings best depicts the electrical activity of a muscle group that has a very high force arm:resistance arm ratio at 135 ?

V Shape - lowest EMG activity where there is the best leverage (a high force arm:resistance arm ratio)

Which of the following fiber types would tend to have the lowest ATPase activity? I IIX IIAX IIA IIC

I

Which of the following fiber types would tend to have the lowest PFK (phosphofructokinase) activity?

I

Which of the following fiber types would tend to have the most myoglobin? IIX I IIAX IIA IIC

I

Which of the following EMG tracings best depicts the electrical activity of a muscle group performing a 3 second isometric action (ignore joint angles listed below figures)?

EMG activity the same from 90 to 180

Which of the following fiber types would tend to store the least intramuscular triglycerides (lipids)? IIX IIAX IIC IIA I

IIX

___________________________________ is related to the orderly recruitment of motor units from smallest to largest

Size Principle

___________________________________ is when more motor units are stimulated more frequently to produce more force.

Twitch Summation

Which of the following EMG tracings best depicts the electrical activity of a muscle group that has a very low force arm:resistance arm ratio at 135 ?

right side up arch

Which of the following would require the least amount of motor unit recruitment with a 15 lb weight? a. they would all be about the same b. isometric bicep curl 0 deg/sec c. concentric bicep curl 30 deg/sec d. eccentric bicep curl 30deg/sec

D

If we observed an increase in EMG amplitude when our subject lifted a heavier weight, this would be evidence of what type of summation? a. asyncrhonous motor unit recruitment b. twitch summation c. teporal summation d. spatial summation e. multiple motor unit summation

E

The far left panel depicts the torque curve for a muscle group performing an eccentric action. Which of the other curves best represents the torque curve you would expect to see for this same muscle group during a concentric action? - Description: upright arch

upright arch but smaller

In our recent lab we did experiments related to several aspects of muscle performance including force, velocity, power, and muscle length. Which of the following figures best depicts the force-velocity curve during concentric and eccentric actions?

upside down T, backwards S