Physical (In) activity

Question 1

List some reasons why it is important to measure physical activity levels.

Answer 1

Reasons to measure physical activity levels include its direct relationship with disease endpoints, its indirect relationship with disease through the effects of activity on diet or body weight, the ability to study physical activity patterns, determinants, and barriers in different groups, and its relevance for a wider segment of the population. Additionally, it is important to evaluate physical activity interventions.

Question 2

Define physical activity

Answer 2

Physical activity is defined as bodily movement generated by skeletal muscles resulting in energy expenditure (heat production)

Question 3

What are the two main divisions of energy expenditure mentioned?

Answer 3

The two main divisions of energy expenditure mentioned are Non-exercise activity thermogenesis (NEAT) and Voluntary physical activity

Question 4

What are some tools used for measuring energy expenditure?

Answer 4

Tools for measuring energy expenditure include Metabolic Cart, Metabolic Chamber, and the Doubly Labelled Water Technique

Question 5

What does a metabolic cart measure, and what does this indicate?

Answer 5

A Metabolic Cart measures O2 and CO2, which provides a good indication of what the participant is doing

Question 6

How does a metabolic chamber work?

Answer 6

A Metabolic Chamber samples the gas of the air that the participant is living in.

Question 7

Describe the Doubly Labelled Water Technique

Answer 7

The Doubly Labelled Water Technique uses water that has isotopes of O2 and H. By tracking their elimination, specifically how CO2 is part of the metabolic process and O2 is expired in CO2, knowing how much was ingested and excreted can give an estimate of energy

Question 8

What does MET stand for, and what is 1 MET defined as?

Answer 8

MET stands for Metabolic Equivalent of Task. 1 MET is defined as the Amount of Oxygen Consumed at Rest

Question 9

What is the approximate value of 1 MET in terms of oxygen consumption?

Answer 9

1 MET ≈ 3.5 mL O2 / kg / min

Question 10

From whom and under what conditions was the data for the 1-MET value derived?

Answer 10

The data on which the 1-MET value was derived was from the resting V̇O2 for one 70-kg, 40-yr-old man

Question 11

What is METs useful for and when is it less useful?

Answer 11

METs is useful as a unit of benchmark against activity, but it is useless at rest.

Question 12

How is (in)activity classified based on MET values?

Answer 12

(In)activity is classified as follows: 0-1.5 METs is sedentary, 1.5-3 METs is light PA (ADL), 3-6 METs is MVPA (Moderate-to-Vigorous Physical Activity), and >6 METs is vigorous activity

Question 13

Define physical inactivity

Answer 13

Physical inactivity is defined as “An insufficient physical activity level to meet present physical activity recommendations”

Question 14

Define sitting according to the Sedentary Behaviour

Answer 14

Sitting is “A position in which one’s weight is supported by one’s buttocks rather than one’s feet, and in which one’s back is upright”. The notes also state that you can sit and be active, like riding a bike

Question 15

Define lying

Answer 15

Lying is “Being in a horizontal position on a supporting surface”. The notes also mention that one can also be lying down and be Physically active

Question 16

Define standing

Answer 16

Standing is “A position in which one has or is maintaining an upright position while supported by one’s feet”. The notes also indicate that one can stand and be engaged in activities

Question 17

Define sedentary behavior based on energy expenditure and posture.

Answer 17

Sedentary behavior is “Any waking behavior characterized by an energy expenditure ≤1.5 metabolic equivalents (METs), while in a sitting, reclining or lying posture”

Question 18

Is sleep considered sedentary behavior?

Answer 18

No, sleep is NEVER sedentary behaviour

Question 19

Are physical activity and sedentary behavior mutually exclusive?

Answer 19

No, PA sedentary are not mutually exclusive. The notes emphasize that just because someone gets 150 minutes of MVPA a week does not mean they are not sedentary

Question 20

How do sedentary and active behaviors often differ throughout the week?How do sedentary and active behaviors often differ throughout the week?

Answer 20

People tend to be more sedentary on the weekdays and more active on weekends

Question 21

What is important to consider when trying to get an accurate representation of physical activity?

Answer 21

Sampling across time is needed to get an accurate representation of PA

Question 22

What does “GIFTS” stand for in the context of self-reporting of physical activity?

Answer 22

“GIFTS” refers to Self-reporting methods

Question 23

What are some pros of self-reporting for assessing physical activity?

Answer 23

Pros of self-reporting include Ease of use (implementing/scoring), being Inexpensive, and being Easy to deliver on a large scale.

Question 24

What are some cons of self-reporting for assessing physical activity?

Answer 24

Cons of self-reporting include Social desirability bias, issues with Memory/Recall, and a potential lack of Familiarity with terminology

Question 25

What is important to consider when using physical activity questionnaires?

Answer 25

Physical activity questionnaires have to be population relevant

Question 26

How long have physical activity questionnaires been developed and for what purposes?

Answer 26

Physical activity questionnaires have been Developed over the past 20+ years and come in Short and Long versions for epidemiological and research purposes

Question 27

What kind of studies have been conducted on physical activity questionnaires?

Answer 27

Many validation studies (normative data) across a variety of populations have been conducted

Question 28

In how many languages have physical activity questionnaires been translated?

Answer 28

They have been Translated into 15+ languages

Question 29

What behavior do some physical activity questionnaires also incorporate?

Answer 29

Some questionnaires also Incorporate Sedentary Behaviours.

Question 30

What is the range of validity for self-report measures of physical activity compared to objective measures?

Answer 30

There is a Large Range of Validity (various groups/tasks) in Comparison to Objective Measures

Question 31

What is the validity of the "International Physical Activity Questionnaire"?

Answer 31

The validity of the "International Physical Activity Questionnaire" ranges from excellent to poor depending on outcome, activity type, and cohort

Question 32

Name some objective measurements of activity.

Answer 32

Objective measurements of activity include Pedometers (step counters), Accelerometers, and Heart rate monitors

Question 33

How is heart rate related to oxygen consumption during submaximal aerobic activities?

Answer 33

HR is linearly related to VO2 during submaximal aerobic activities

Question 34

What are some advantages of using heart rate monitors for physical activity assessment?

Answer 34

Heart rate monitoring is a Good method of physical activity assessment, Very practical in the field, and Able to store data allowing for the Estimation of frequency, intensity, and time of physical activity for days-weeks.

Question 35

How do pedometers work?

Answer 35

Pedometers detect vertical accelerations of the body and record a "step" when vertical acceleration exceeds a threshold value.

Question 36

What are pedometers accurate for recording?

Answer 36

Pedometers are Accurate for recording the number of steps taken and distance walked. Their reliability increases for faster walking and running paces, and their accuracy is not affected by walking or running surface

Question 37

What is the relationship between step counts and energy expenditure?

Answer 37

The relationship between step counts and energy expended is strongest for moderate-intensity activities, and step count is more accurate than kilocalorie estimates. However, they only measure movement in one plane

Question 38

What are some problems with pedometers?

Answer 38

Problems include decreased sensitivity if tilted away from the vertical plane, which can occur in obese individuals at slow walking speeds if the belt is tilted. However, the Ankle devise (StepWatch 3) is sensitive enough to detect frail, slow, shuffling steps

Question 39

How do accelerometers measure movement?

Answer 39

Accelerometers measure movement based on acceleration and deceleration of the body

Question 40

Where can accelerometers be worn, and what do their measurements relate to?

Answer 40

Accelerometers can be worn on the trunk or limbs, and their measurements are proportional to muscular forces, with most results being in proportion to energy expenditure. They provide information on the frequency, intensity, time (FIT) of physical activity

Question 41

What type of accelerometers is considered best for research?

Answer 41

accelerometers that measure in three planes (vertical, horizontal, mediolateral), also known as triaxial accelerometers, are the best types for research

Question 42

What are some advantages of using accelerometers?

Answer 42

Advantages include their small size and ability to record data over long periods, the ability to download data and segment physical activity time periods, and the fact that the same accelerometer can be worn repeatedly by different participants. Some models do not pickup non-ambulatory movement like cycling but can pick up nuanced upper body movements unlike the actigraph and can be worn in the same way as an actigraph and can be used for swimming

Question 43

What are some limitations of accelerometers?

Answer 43

Limitations include that they require more time and resources than a pedometer (technical expertise, hardware, and software for calibration, input, download, and analysis), single-plane models may not accurately detect movement from activities such as bicycling, weightlifting, or swimming, they are unable to detect increased activity level resulting from upper body movement, carrying a load, or surface changes (e.g., hills), and equations that estimate energy expenditure may not apply to free-living situations. They also need to be worn for a minimum of 5 days including the weekend

Question 44

How well does heart rate monitoring correlate with indirect calorimetry?

Answer 44

Indirect calorimetry is highly correlated (0.87) with HR monitoring, with a stronger correlation than accelerometers (vs calorimetry) for lifestyle activities

Question 45

How might combining accelerometer and heart rate monitoring improve assessment?

Answer 45

Wearing an accelerometer and an HR monitor together may improve energy expenditure estimation and classification of time spent in light, moderate, and hard activity

Question 46

What are some limitations of heart rate monitoring for estimating energy expenditure?

Answer 46

Limitations include that HR is increased by temperature, humidity, and high altitude, which may lead to overestimation of energy expenditure. Also, emotional state, hydration status, type of contraction (static vs. dynamic), and the amount of muscle mass recruited will affect HR, independent of physical activity level

Question 47

What is an advantage of heart rate monitors that use multiple inputs?

Answer 47

Some monitors use a combination of accelerometer and physiological signals to predict / calculate energy expenditure, examples include SenseWear Armband and Actiheart

Question 48

What can GPS devices provide accurate assessments of in terms of physical activity? What are some limitations?

Answer 48

GPS can provide accurate assessments of speed, ranging from slow walking to fast running. It may be used indoors or outside but cannot be used for stationary activity (e.g., biking)