Measuring Physical Activity Behaviour and Level

Question 1

Why measure physical activity?

Answer 1

• precise measurement of physical activity and physical activity related energy expenditure is a pre-requisite for internal validity of health research
• document frequency and distribution of physical activity in defined population
• dose-response for physical activity and health benefits
• identify factors that influence physical activity behaviour

Question 2

Self-Report Measures

Answer 2

• questionnaires
• diaries
• interviews

Question 3

Accelerometry

Answer 3

• digital recording of the intensity of movement produced during activity

Question 4

Pros and Cons of Accelerometry

Answer 4

Pros:
- evaluates frequency, intensity, and duration
- non burdensome
Cons:
- can’t account for increased energy cost associated with static and resistance exercise
- innacurate estimates for activities that involve limb movements
- e.g cycling, rowing
- cost

Question 5

Max HR for an individual 18 years old

Answer 5

220-age: 202

Question 6

Heart Rate

Answer 6

• minute by minute heart rate data

- physical activity intensity determined by % max heart rate

Question 7

Pros and Cons of Heart Rate

Answer 7

Pros:
- physiological measure
- minute-by-minute data
- non burdensome
- low cost
Cons:
- factors unrelated to activity influence HR
- remains evalated after movement stops
- using HR to predict EE can be difficult (need to consider fitness and weight)

Question 8

Combined Sensing (HR and Acc.)

Answer 8

• the biomechanical limitations associated with accelerometry and biological limitations associated with HR are not correlated

Question 9

The Actiheart

Answer 9

• attaches to the chest via two adhesive electrodes

- minute-by-minute accelerometry and HR data

Question 10

Pros and Cons of the Actiheart

Answer 10

Pros:
- noninvasive
- combines HR and accelerometry in one device
- more precise measure of PAEE than HR or accelerometry alone
Cons:
- new device
- little validity for device
- cost

Question 11

Doubly Labeled Water

Answer 11

• A drink mix containing two stable isotopes: Deuterium and Oxygen-18
• differences in the elimination of 2H and 18O used to estimate carbon dioxide
• CO2 rates utilized to calculate daily total energy expenditure

Question 12

Pros and Cons of Doubly Labeled Water

Answer 12

Pro:
- unobtrusive and noninvasive
- gold standard for estimating free-living PAEE
Cons
- cost
- only provides information on total EE (need information about resting energy expenditure

Question 13

Study: the SQUASH in Adolescents: A doubly Labelled Water Study

Answer 13

• TEE was measured during the nine days with DLW
• Urine samples collected on days 1, 5 and 9
• Day 10: SQUASH assessed commuting activities, Leisure time activities, household activities, and activities at work and school over the last 9 days
  Conclusion:
• when using highly active adolescents, the SQUASH is a valid self-reported tool for measuring PAEE
  Recommendations:
• before the SQUASH can be recommended as a valid questionnaire for assessing PAEE, these findings need to be replicated in larger more diverse samples
  Implications:
• intervention efforts designed to help children achieve a healthy energy balance are only as good as the instruments that are used to measure PAEE
• Self-reported instruments to measure PAEE should be short and simple so that they can be used in large population based studies

Question 14

Calculating PAEE from DLW and SQUASH

Answer 14

• DLW (TEE - Resting energy expenditure = PAEE)

- SQUASH (used child and youth compendium to assign energy costs to physical activities - PAEE)