Muscle changes with ageing

Question 1

What is ageing a problem?

Answer 1

• ^ incidence of non- communicable diseases >75 ( Diabetes, Cancer etc)
• Last 10-15 years = poor health

Question 2

What are the impacts of ageing on body composition?

Answer 2

• Osteogenesis and Myogenesis decline
• Adipogenesis predominates
• Bone formation is lower than bone resorption
• Bone mass decreases
• Muscle mass decreases

Question 3

What causes Osteosarcopenic Obesity and what does it lead to?

Answer 3

Causes:
- Bone Loss (Osteopenia/ Osteoporosis)
-Muscle Loss (Sarcopenia)
- Fat gain (adiposity)

Leads to :
_ ^ risk of fractures
- decreased functionality
- ^ Morbidity

Question 4

What is the rate of loss of mass in Men and Women >45?

Answer 4

0.47 & 0.37%/yr - Men vs Women

Question 5

What is Dynapenia?

Answer 5

Rate of Loss of Function/ Strength
Men = 3.5%/yr
Women = 2.7%/yr

Question 6

Why is sarcopenia important?

Answer 6

10% - Decreased immunity / increased risk of infection
20%- Decreased wound healing , Increased muscle weakness, Increased risk of infection
30% - Difficulty sitting , Pressure ulcers, Pneumonia, Inability to heal
40% - Increased risk of death, usually from pneumonia

Question 7

How does sarcopenia affect Metabolism and function?

Answer 7

• Amino Acid Substrate used to support repair processes
• Maintain the immune system (Glutamine as fuel)
• Frality - leads to a viscous circle
• Inactivity / bed bound - Loss of muscle
• “Respiratory Failure”

Question 8

Explain fatty infiltration in Ageing

Answer 8

• Lipid droplets in skm are deposited in a highly organised manner , revealing a string of punctuated red lipid droplets if examined in Oil red O-stained sections imaged in fluorescence microscopy

Question 9

What would an electron micrograph of skm size and abundance of mitochondria and intramyocellular lipid droplets reveal in older muscle ?

Answer 9

• Greater density and size of IMCL
• Reduced number of mitochondria in aged skm

Question 10

What are the effects of ageing on nutrition?

Answer 10

Undernutrition and inactivity - loss of muscle and energy
Overnutrition = increased adiposity and metabolic dysfunction

Question 11

Give an overview of carb metabolism

Answer 11

• Glycogen stores 350-500 g max, only 100f in Liver
• Depleted by fasting and exercise
• Refilled feeding and GNG
• Ageing? smaller muscles/ mass
• Lower activity levels

Question 12

Give an overvire of Fat metabolism

Answer 12

• Excess Dietary Fat, CHO and protein
• Energy sources
• Energy balcnce met
• Excess Carbon skeletons
• Fat stores increase

Question 13

What is the role of stem cells in ageing muscle?

Answer 13

• Satellite cells less responsive to muscle repair
• Affected myogenic program/ decreased activation rate
• Loss of sat cells = decrease in quiescence capacity, Cell death senescence

Question 14

What is the theoretical relationship b which inflammation induces muscle dysfunction?

Answer 14

• Inflammation associated with cytokine release
• Cytokines, activate mitochondria
• Increase free radicals - very reactive- proteins/DNA
• Downstream targets - Cell damage and Impact protein turnover

Inflammation — oxidative stress– Mitochondrial dysfunction = Cell/ Tissue loss