Exercise and the Skeleton

Question 1

What are the three elements that effect health

Answer 1

Physical inactivity
Obesity
Sedentary behaviour

Question 2

Describe facts on physical inactivity

Answer 2

4th leading risk for global mortality

6th of all deaths are attributed to physical inactivity

Question 3

Define cardiorespiratory

Answer 3

The ability of the circulatory and respiratory systems to supply oxygen to skeletal muscles and the muscles ability to absorb and utilise the oxygen ruing physical activity

Question 4

Define fitness

Answer 4

Condition of being physically fit and healthy

Question 5

Define physical activity

Answer 5

Any bodily movement produced by skeletal muscles that requires energy expenditure

Question 6

What is 1 MET

Answer 6

metabolic at rest

Question 7

How do you measure physical activity

Answer 7

Self report

Direct observation

Heart rate monitoring

Accelerometery

Inclinometry

Portable indirect calorimetry

Doubly labelled water

Question 8

What is an accelerometer

Answer 8

Small, lightweight, unobtrusive

Record the time, duration, frequency and intensity of walking or running movements

e.g. smart watch

Question 9

What is the proper way to test fitness

Answer 9

Cardio pulmonary exercise test

CPET/CPEx

Question 10

Describe the Myers 2002

Answer 10

Patients referred for exercise testing

Followed up 6.2 years after
Death was end point

Fitness directly related to death

Question 11

What does fitness do

Answer 11

Offset the risk of obesity

Normal weight and unfit doubles the risk of mortality

Obese and fit almost negates this risk

Question 12

What is the equation of strain

Answer 12

Force (F) causes deformation (pieL)

Strain = pieL/L

Question 13

What is the strain based feedback loop

Answer 13

Customary strain (incorporates all variables)

Decreased activity - lower than customary strains = bone loss

Increased activity - higher than customary strains = bone formation

Question 14

What are the strain variables

Answer 14

Magnitude
Rate (up and down)
Frequency
Dwell (hold/rest periods) - enhance the responses
Number of cycles

Question 15

What is the mnemonic SSCSS

Answer 15

site specific customary strains stimulus

Depends on the area to the affect on the bone

Question 16

What effects SSCSS

Answer 16

Sex

Age

Biochemicals e.g. hormones, cytokines

Drugs/medicines/nutraceuticals

Question 17

Describe the mechanostat theory

Answer 17

Effect of SSCSS along with the variables which effect these

Question 18

Describe the nature of exercise induced stimulus

Answer 18

Bones respond physiologically to occasional high magnitude high rate events

Other stimuli may affect the system

Bone retain information on previous exercise
- respond maximally to only a few loading cycles each day
- exercise in pervious 4 hours increases the subsequent loading
- Bone responds to very brief mechanical events (milliseconds)
- rest periods between single loading events (approx. 10 seconds) increase their effect

Question 19

What are the mechanosensors and mechanotranducers in bone

Answer 19

Osteocytes

Question 20

How do osteocytes sense loading

Answer 20

Hydrostatic pressure

Direct cellular deformation

Fluid flow shear stress (FFSS) - think as if when beach footprints are made

Question 21

Describe osteocytes function

Answer 21

1. bone remodelling process
   - osteocytes regulate activities of osteoblasts and osteoclasts via signalling molecules
2. Perilacunar/canalicular remodelling (PLR)
   - osteocytes regulate local bone matrix resorption and restoration
3. Endocrine signalling
   - osteocytes secrete endocrine factor, FGF23, targeting other organs such as kidneys, heart, parathyroid and intestines

Question 22

What factors affect intercellular communication during exercise

Answer 22

Age
Gender
Genotype
Diet
Environment
Endocrine background

Question 23

Describe ageing related bone loss

Answer 23

Males - decreasing bone mass with age

Females - bone loss due to menopause