10. Ageing, Sarcopenia and Anabolic Resistance

Question 1

What is sarcopenia?

Answer 1

syndrome characterised by progressive and general loss of skeletal muscle mass and strength with an increased risk of adverse outcomes like physical disability and poor quality of life, death.

Question 2

what is dynapenia

Answer 2

age-related loss of muscle strength

Question 3

what is kratopenia

Answer 3

Age-related loss of muscle power

Question 4

what can muscle wastage come from?

Answer 4

inactivity
Anabolic Resistance
Inflammation
hypercortisolemia

Question 5

What are the underlying causes of sarcopenia?

Answer 5

Motor neuron death
- leading to a decrease in number of motor units and fibre number.
Hormonal factors - decreases in testosterone and oestrogen
Lifestyle factors - decrease in physical activity. malnutrition. Decrease in dietary protein.
Decrease in fibre size
Increase in inflammatory factors.

Question 6

Explain the process of how sarcopenia leads to frailty, disability, mortality?

Answer 6

Decrease in muscle mass leads to 2 pathways

1. Decrease in strength and a decrease in power which leads to a decrease in walking speed, increasing risk of falls and a risk of fracture.
2. Decrease in lean body mass and an increase in fat mass. This leads to a increase in type 2 diabetes and an increase in insulin resistance.

Question 7

what happens when older people are exposed to resistance training in regards to sarcopenia

Answer 7

Their basal metabolic rates increase to prolong the onset of a decrease in muscle mass.

Question 8

How does disuse induce anabolic resistance in aged muscle

Answer 8

elderly muscles are less responsive to low/moderate dose protein feeding than the young, They need a higher protein dose for sustained muscle mass

Question 9

In a normal person, they have a skewed daily protein distribution (most protein at dinner) but this fails to maximise potential for muscle growth. what is the better alternative to maximise this?

Answer 9

evenly distributed protein ingestion may facilitate repeated maximal stimulation of protein synthesis and maintenance of muscle mass

Question 10

What are the preliminary mechanisms underpinning anabolic resistance in ages muscle?

Answer 10

• When protein is taken in during the day - most people have a skewed protein intake
• old people have a resistance to mechanical loading - much less able to increase their rate at which they build muscle
• Muscle protein synthesis does not match muscle protein breakdown (it is lower)

Question 11

How can older individuals still increase muscle mass?

Answer 11

• Prior exercise increases the anabolic response to feeding in the elderly.
• Resistance exercise is effective for muscle hypertrophy and strength gains in older adults, through restoration of muscle anabolic sensitivity.