PA and Exercise

Question 1

What is physical activity?

Answer 1

Any force exerted by skeletal muscle that results in energy expenditure above resting level

Question 2

What is exercise?

Answer 2

A sub-component of physical activity that is planned or structured

Question 3

What are the challenges to understand the impact of one factor (e.g. PA) on health?

Answer 3

• Measurement of PA is difficult

- Cannot design and conduct experimental studies to establish the highest level of proof

Question 4

What are some measurement tools of PA and exercise?

Answer 4

• Questionnaires
• Other self report (e.g. diary)
• Pedometers
• Accelerometers
• Heart rate monitors
• Synchronised HR+accelerometer
• Doubly labelled water
• Fitness

Question 5

What is double labelled water?

Answer 5

The rate of CO2 production is calculated with the difference between the rates of enrichment of 18O and 2H (heavy isotopes)
18O lost faster (in CO2 and H2O) compared to 2H (only H2O)

Question 6

What are the limitations of DLW?

Answer 6

• High cost and very specialised staff required for analysis
• Assumed RER (of 0.85)
• No info on distribution of activity

Question 7

What is the epidemiological assessment of PA on health?

Answer 7

-Observational
-Allow nature to take its course and analyse relationships between indices of health status and other variables
Issue: cannot prove causality

Question 8

What is the laboratory-based assessment of PA on health?

Answer 8

-Experimental
-Intervene to see what happens to some/all individuals
Issue: Tend to measure surrogate outcomes

Question 9

What is epidemiology?

Answer 9

The study of the distribution and determinants of health related states or events in specified populations and the application of the study to control health problems

Question 10

What is the Harvard Alumni Study?

Answer 10

Cohort began in 1962, studied health outcomes (CVD, longevity, diabetes, cancer…)
Able to draw associations but not causal evidence
e.g. impact of smoking on mortality is high compared to sedentary lifestyle

Question 11

What are RCTs?

Answer 11

Measure outcomes over time since cannot measure mortality
Assess effect on ‘risk factors’
Can only draw causal inferences linked to measured outcomes
Solution: combine measurements for stronger evidence