Healthy Ageing

Question 1

At what age does the muscular strength start to decrease ?

Answer 1

• 30 years old
• more pronounced around 50-60 years old

Question 2

Define sarcopenia and its causes

Answer 2

• sarcopenia occurs with advancing age
• it’s the «poverty of flesh» defined as the loss of muscle mass of about 15% to 20%

The main factors are :
- physical inactivity
- alterations in nervous system
- altered hormonal levels
- decreased energy and proteins

Question 3

What is the other cause of muscle mass loss in elderly ?

Answer 3

Dynapenia : the age related loss of muscle mass caused by muscular and neural adaptation

Question 4

What are the neural adaptations taken into consideration in the concept of dynapenia ?

Answer 4

• decrease in cognitive function
• decrease in supraspinal drive
• decrease in spinal excitability
• decrease in motor unit recruitment and discharge rate

Question 5

What are the muscular adaptations taken into consideration in the concept of dynapenia ?

Answer 5

• hormonal changes
• immunological changes
• sarcopenia
• decrease in the contractile quality

Question 6

What is atrophy

Answer 6

Decrease of muscle fiber size
In elderly it affects more type II fibers (fast)
The decrease is greater in the lower limbs than upper limbs

Question 7

What is hypoplasia ?

Answer 7

The decrease in the number of muscle fibers caused by the decrease in the synthetisis of contractile protein and the proteolysis within each fiber.

Question 8

What happens to intrinsic ability to generate force in elderly ?

Answer 8

The intrinsic ability of muscle fibers to generate force is decreased by aging
Both type I and type II fibers are affected

Question 9

Define the excitation-contraction coupling and how it is affected by aging

Answer 9

Physiological process that converts sarcolemma action potential into muscle contraction and force generation.
With age there is a reduction in dihydropiridine receptors and an uncoupling between dihidropyridin receptors and ryanodin which leads to deficits in calcium release.

Question 10

Define adipocyte infiltration and its consequences in elderly

Answer 10

Adipocyte infiltration is the infiltration of adipose tissue that accumulates with age, producing inflammatory cytokines into circulation that may accelerate muscle catabolism and contribute to cycle of muscle loss and fat accumulation.

Question 11

Describe the muscle alteration due to aging

Answer 11

• decrease in pennation angle
• decrease in facial length
• suggesting a loss of sarcomere

Question 12

Describe the alteration in tendon properties in elderly and its consequences

Answer 12

• increase of tendon compliance
  Causing a decrease rate of force development and reduces the ability to produce rapid force

Question 13

Why is the number of MU decreased in elderly ?

Answer 13

Gradual decrease of number of MU takes place until 60 years old then rapidly increases.
This is due to the apoptosis phenomena which is the death of MN in the spinal cord due to neurotoxic factors leading to the denervation of corresponding muscle fibers.

Question 14

Explain the phenomena of MU remodeling in elderly

Answer 14

Due to the death of some MN, the corresponding muscles are denervated.
The surviving MNs develop collaterals that will innervate some of the denervated muscle fibers.
This leads to the formation of giants MU with age.
Re innervation happens in muscle fibers type I.

Question 15

Describe the alteration in sensory pathways in elderly

Answer 15

• decrease in H-reflex amplitude
• decrease in the efficiency of Ia fibers to activate spinal motoneurons
• increase in presynaptic inhibition
• seniors use the downward pathways more extensively
• shift on the reliance on peripheral to cortico spinal pathways to control the activity of muscles