Muscle aging - Week 4

Question 1

At what ages do our muscle strength decline?

Answer 1

Begins at age 40

Becomes more rapid at age 70

Question 2

What gender is more effected my muscle strength loss ?

Answer 2

Men

Question 3

Which part of the body suffers more muscle strength loss and possible reason ?

Answer 3

Lower body loses 40%

Compared to upper body at 33% decrease

Can be due to increase in sitting as we get older so arms and hands would be used more

Question 4

What is the equation for power?

Answer 4

Power = force x velocity

Question 5

What is important for function and why?

Answer 5

Rate of force production

Helps prevent falls

Question 6

What happens to our limbs due to loss of muscle mass when we get older? (2)

Answer 6

Increase in subcutaneous fat

Increase in inter muscular fat - makes harder for muscular contraction

Question 7

From the age of 40 what percent of muscle is lost till 70?

Answer 7

8% per decade

0.5-1% per annum

Question 8

From the age of 70 what percentage of fat is lost ?

Answer 8

Up to 15% per decade

Question 9

Which gender has a steeper regression in body mass over time ?

Answer 9

Men

Question 10

Which type of muscle fibres are more effected by atrophy?

Answer 10

Type 2 muscles are more affected compared to type 1

Question 11

Is more mass lost or more strength lost with atrophy ?

Answer 11

More strength is lost

Can still have muscle mass but strength decreases

Question 12

What does loss of muscle fibres cause?

Answer 12

Decrease in force production

decrease/slower muscle contraction

Question 13

What is a possible reason for fat accumulation with age ?

Answer 13

Decrease in exercise so muscle is lost and fat increases as fat isn’t used as a fuel source

Question 14

What happens to motor units with age
/

Answer 14

Less motor units

Leads to less muscle activation

Question 15

What does the loss of motor units lead to ? (3)

Answer 15

Muscle fibres become denervated

Causes muscle atrophy and fibre loss

Less force can be produced as a result

Question 16

What happens to type 2 muscle fibres as we age (4) ?

Answer 16

Type 2 become denervated from type 2 MU

Type 1 MU branch out and innervate type 2 fibres

Type 2 fibres then develop type 1 characteristics

Less type 2 fibres as a result of age

Question 17

What happens to motor units as a result of type 2 muscle fibre denervation?

Answer 17

Motor units become bigger

All fibres would be activated at once which makes it harder to do fine motor skills

Decrease in motor unit efficiency

Question 18

What happens to fibre type grouping and sharp change with age?

Answer 18

Type 1 fibres become more clustered together due to increase in type 1 MU

Type 2 fibres get squashed and misshapen , become less efficient

Leads to increased fat accumulation in muscles

Question 19

In terms of fatigue what happens with muscles with age?

Answer 19

Due to increase in type 1 fibres, muscular fatigue resistance increases

Question 20

Overall how does denervation alter muscle characteristics ?

Answer 20

Increased co-expression of myosin isoforms

Decreased force output

Decreased velocity of contraction and power

Question 21

Overall how does reinnervation alter muscle characteristics ? (2)

Answer 21

Increased size of MUs - less efficient

Some preservation in muscle mass

Question 22

What changes occur for excitation-coupling process ?

Answer 22

Decrease in Ca+ release from SR

Changes to SR function , decrease Ca+ uptake

Slowing of myosin molecule, decreases speed of shortening/contraction

Reduced acto-myosin cross bridges, decreases force output

Question 23

How does being an athlete with lots of muscle compared to an untrained person differ with age ??

Answer 23

Athlete has more muscle mass reduction

Athlete still ends up with more muscle than untrained people so can still produce more force

Question 24

Age is associate with loss of muscle mass , what is this termed ?

Answer 24

Sarcopenia

Question 25

Disease related muscle wasting is termed ?

Answer 25

Cachexia