week 5 sem 2

Question 1

Skeletal muscle tissue has several functions but three relate specifically to human movement

Answer 1

Maintenance of upright body posture
Movement of the trunk and limbs
Shock absorption

Question 2

Muscle Size

Answer 2

Force proportional to number of actin-myosin crosslinks
Force proportional to size of mu

Question 3

Type I (oxidative)

Answer 3

Small diameter
* Dark (mitochondria and more
myoglobin)
* Slow twitch (slow oxidative)
* Fatigue resistant
* More capillaries and higher O2
supply
* Aerobic metabolism due to the
presence of oxidative enzymes

Question 4

Type IIX (IIB) (glycolytic)

Answer 4

• Larger diameter
• Pale (less mitochondria and
  myoglobin)
• Fast twitch (fast glycolitic)
• Faster to contract, stronger force
  production but fatigue quickly
• Anaerobic metabolism

Question 5

Skeletal muscle innervated by

Answer 5

large type A or Alpha (α) motor neurons

Question 6

The Motor Unit

Answer 6

Motor neuron
+ its axon
+ all of the muscle fibres it
innervates

Question 7

low innervation ratio

Answer 7

fine motor skills

Question 8

high innervation ratio

Answer 8

gross motor skills

Question 9

The strength of a muscle contraction can be controlled by:

Answer 9

• Initially activating neurons with smallesti nnervation ratio (contract few muscle fibres)Henneman’s size principle
• Increasing the number of motor units activated at one time Recruitment
• Increasing the frequency of stimulation of individual motor units rate coding

Question 10

Muscle strength

Answer 10

The maximal amount of force or tension
that a muscle (or muscle group) can
voluntarily exert
➢Represents torque

Question 11

Muscle Endurance

Answer 11

➢The ability of a muscle (or muscle group) to
perform repeated contractions, against
resistance, or maintain an isometric contraction
for a period of time
➢10km run
➢Holding wall squat
➢Plank

Question 12

Muscle power

Answer 12

The product of muscular force and velocity
of contraction
➢Represents the rate of torque production
➢Jumping
➢Sit-stand
➢Throwing a ball- baseball pitch

Question 13

Functional Tests

Answer 13

• Walking - 10 metre walk test, 6-minute walk test
• Sit to stand - 30s STS, 5 x STS
• Global LL function – Timed Up and Go test
• Squat, bridge
• Jump, hop, run

Question 14

Isokinetic Testing

Answer 14

reliable yes
valid- maybe
practical- no

Question 15

isotonic test eg free weights

Answer 15

Reliable yes
* Valid yes
* Practical no

Question 16

Isometric Testing
* e.g. Hand-held Dynamometry

Answer 16

• Reliable yes
• Practical yes
• Valid maybe not

Question 17

Hand-held Dynamometry advantages

Answer 17

✓Portable
✓High reliability at higher
grades
✓High sensitivity for more
subtle changes in mm

Question 18

Hand-held Dynamometry disadvantages

Answer 18

❖Expensive
❖Unreliable when large forces
generated
❖Poor validity due to isometric
testing only

Question 19

Manual Muscle Testing (MMT)

Answer 19

An attempt to determine the subject’s
ability to contract a muscle or muscle
group voluntarily

Question 20

Manual Muscle Testing (MMT) advantages

Answer 20

✓Convenient
✓Versatile
✓Quick to apply
✓Inexpensive means to test
strength

Question 21

Manual Muscle Testing (MMT) disadvantages

Answer 21

❖Poor sensitivity to small change
❖Unreliable at higher grades
❖May be physical limitations of
therapist

Question 22

MMT Grading System

Answer 22

0- no observable or palpatable muscle contraction
1- observable or palpatable muscle contraction, but unable to get to FROM
2- FROM not aginat gravity
3- FROM against gravity
4- FROM against gravity and some manual resistance
5- normal- FROM against gravity and manual resistance

Question 23

Precautions and Contraindications to MMT

Answer 23

×Inflammation present in region
×Pain is present
Care taken when:
❖History of or at risk of CV problems
❖Abdominal surgery or herniation
❖Situations where fatigue detrimental