The NPAG and Measuring Physical Activity


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Examines subjective and objective methods of assessing physical activity and sedentary behaviour, including recall surveys or diaries, pedometry, accelerometry and observational tools, in relation to the National Physical Activity Guidelines.

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The NPAG and Measuring Physical Activity

  1. 1. The guidelines and measuring physical activity
  2. 2. Outline <ul><li>In consultation with health professionals the Australian Government has published a set of physical activity guidelines known as the National Physical Activity Guidelines </li></ul><ul><li>The guidelines are different for various age groups and aim to achieve health benefits in the population </li></ul><ul><li>Health agencies and other organisations as well as individuals collect data on physical activity </li></ul><ul><li>One of the key purposes is to see whether the guidelines are being adhered to </li></ul><ul><li>There are many tools that can be used to measure this </li></ul>
  3. 3. Key Knowledge/Skills <ul><li>Subjective and objective methods of assessing physical activity and sedentary behaviour, including recall surveys or diaries, pedometry, accelerometry and observational tools, in relation to the National Physical Activity Guidelines </li></ul><ul><li>Compare and contrast subjective and objective methods of assessing sedentary behaviour and physical activity compliance with the National Physical Activity Guidelines </li></ul><ul><li>Collect, measure and evaluate data using subjective and objective methods of assessing physical activity and sedentary behaviour </li></ul>
  4. 4. Dimensions of Physical Activity <ul><li>Frequency : sessions or days per week </li></ul><ul><li>Intensity : amount of effort required for the activity – low (slow walking), moderate (brisk walking), vigorous (jogging) </li></ul><ul><li>Duration : length of session or accrued length of physical activity during a week </li></ul><ul><li>Type : other info about the nature of the activity and its purposes (e.g. strength) </li></ul>
  5. 5. Domains and Context <ul><li>Physical activity occurs in different places; domains </li></ul><ul><li>There are four commonly recognised domains </li></ul><ul><li>These are leisure-time, household/gardening, occupational/school and active transport </li></ul><ul><li>Researches are often interested in seeing how active people are in different domains and why </li></ul><ul><li>Related to this, the context of physical activity is important – are there observers? is physical activity social? etc. </li></ul>
  6. 6. National Physical Activity Guidelines (NPAG) <ul><li>Broken up into age groups </li></ul><ul><li>You are required to state the guidelines </li></ul><ul><li>More importantly, you need to be able to assess whether or not an individual complies to the guidelines </li></ul><ul><li>Sedentary behaviour guidelines inform individuals of what do in their free time while inactive </li></ul>
  7. 7. NPAG – 0-5 Year Olds <ul><li>Children from 0-1 should engage in floor-based play for a sufficient amount of time </li></ul><ul><li>Children from 1-5 should engage in a variety of activities daily, 3 hours + </li></ul><ul><li>No electronic media for children under the age of 2 </li></ul><ul><li>No more than 1 hour of electronic media per day for 2-5 year olds </li></ul><ul><li>All 0-5 year olds should be not kept inactive for more than one hour at a time </li></ul>
  8. 8. NPAG – Children (5-12) and Youth (12-18) <ul><li>Frequency : everyday </li></ul><ul><li>Intensity : moderate - vigorous </li></ul><ul><li>Duration : 60 minutes + (and up to several hours a day for children) </li></ul><ul><li>Type : variety including weight bearing activities and those incorporating fundamental motor skills </li></ul><ul><li>No more than two hours per day of electronic media used for non-educational purposes </li></ul>
  9. 9. NPAG – Adults (18-65) <ul><li>1 – Think of movement as an opportunity, not an inconvenience </li></ul><ul><li>2 - Be active every day in as many ways as you can </li></ul><ul><li>3 – Put together at least 30 minutes of moderate-intensity physical activity on most, preferably all, day </li></ul><ul><li>4 – If you can, also enjoy some regular, vigorous activity for extra health and fitness </li></ul>
  10. 10. NPAG – Adults (18-65) <ul><li>Frequency : Most days (5 or more) </li></ul><ul><li>Intensity : moderate - vigorous </li></ul><ul><li>Duration : 30 minutes + </li></ul><ul><li>Type : variety </li></ul>
  11. 12. NPAG Considerations <ul><li>In many studies, 150 minutes a week (moderate intensity) are considered compliant to the NPAG </li></ul><ul><li>Some research counts vigorous activity as double – e.g. 50 minutes = 100 minutes </li></ul><ul><li>10000 steps – this is the per day guideline for pedometers </li></ul><ul><li>A person not meeting 10000 steps may still be meeting the guidelines </li></ul><ul><li>It can be argued that 4 days per week is sufficient for “most days” of the week </li></ul><ul><li>All interpretations need to be justified </li></ul>
  12. 13. Do they meet the NPAG? <ul><li>Jane walks her dog daily for 20 minutes a day at a brisk pace. She also weeds the garden weekly for about one hour. </li></ul><ul><li>Andrew waters his small garden every second morning for 5 minutes. Each week he vacuums the house for 30 minutes, and once a week he plays tennis with the kids for 45 minutes. </li></ul><ul><li>Anthia walks to work every weekday and notices that her pedometer accrues about 8000 steps a day. After work each day she drops by at the pool for a 10 minute swim to rejuvenate herself. </li></ul>
  13. 14. Yes or No? <ul><li>Jane – Yes in one interpretation. She accumulates 200 minutes of moderate intensity physical activity each week. </li></ul><ul><li>Andrew – No: watering the garden would be considered low-intensity as it only involves holding a hose. Tennis is multiplied by two because it is vigrous but this only brings his total to 135-140 minutes. </li></ul><ul><li>Anthia - We cannot say for sure because the pedometer does not track her swimming. However, 8000 steps is 80% of her daily requirement, and 10 minutes is 33.3% of her daily requirement, so it could be argued that she does meet the guidelines. </li></ul>
  14. 15. Measuring Physical Activity <ul><li>Physical activity levels can be measured using various methods, both subjective and objective. Many things need to be considered before picking a method appropriate to the individual or group. The data collected can then be used to gauge whether or not an individual or group of individuals adheres to the guidelines amongst other things. </li></ul>
  15. 16. Why Measure Physical Activity? <ul><li>to identify factors that influence physical activity levels (determinants) </li></ul><ul><li>to monitor how many people are achieving the National Physical Activity Guidelines </li></ul><ul><li>to identify population trends </li></ul><ul><li>to evaluate the effectiveness of large-scale interventions </li></ul><ul><li>to study the links between physical activity and health </li></ul><ul><li>to determine the amount of physical activity necessary to influence health </li></ul><ul><li>to detect change in an individual's health and/or behaviour </li></ul><ul><li>to determine the effect of any change in physical activity behaviour </li></ul>
  16. 17. Subjective and Objective Measures <ul><li>Subjective measures rely on the opinions of the subject. They are biased and generally less reliable. </li></ul><ul><li>Objective measures rely on the professional and unbiased assessment of physical activity. This may involve tools or humans. </li></ul><ul><li>Humans can observe and report data objectively if they have no relation to the subject and are qualified to collect the data. Solid data from machines is also objective. </li></ul>
  17. 18. Other Considerations <ul><li>Reliability : consistency of measurement </li></ul><ul><li>Accuracy : how precise? </li></ul><ul><li>Validity : will the method measure what needs to be measured or something else? </li></ul><ul><li>Which dimensions need to be measured? </li></ul><ul><li>Can it be used in a lab? Does it measure energy expenditure? </li></ul><ul><li>Cost/accuracy trade-off. As group size increases, cost per person must decrease and this compromises accuracy </li></ul><ul><li>Reactivity; level at which the measure biases behaviour </li></ul><ul><li>Trade off between practicality and accuracy (refer to next slide) </li></ul><ul><li>Participant burden – how much effort/inconvenience does participation require? </li></ul><ul><li>Can it be used in different settings, e.g. a pool? </li></ul><ul><li>Can behavior be observed in different contexts? </li></ul>
  18. 19. The Interrelation Between Practicality and Accuracy
  19. 20. Recalls and Questionnaires <ul><li>include self-administered and interviewer-administered recalls that collect information about various aspects of physical activity </li></ul><ul><li>Proxy reports involve someone else such as a parent or carer reporting on behalf on another individual – e.g. a child or elderly person </li></ul>
  20. 21. Considerations Advantages Disadvantages <ul><li>No reactivity (in most cases) </li></ul><ul><li>Can assess physical activity across multiple domains </li></ul><ul><li>Can capture both qualitative and quantitative information </li></ul><ul><li>Quick and easy for large groups (low burden) </li></ul><ul><li>Cost-effective for large studies </li></ul><ul><li>Accuracy problems due to social desirability bias </li></ul><ul><li>Not suitable for children under 10 or old adults due to cognitive limitations </li></ul><ul><li>Interviewer may be needed to collect data </li></ul><ul><li>Not very accurate due to memory limitations </li></ul>
  21. 22. Logs and Diaries <ul><li>Record detailed information about several dimensions (e.g. type, frequency, intensity and duration) and require participants to document their activity level daily. </li></ul>
  22. 23. Considerations Advantages Disadvantages <ul><li>Can capture both qualitative and quantitative information </li></ul><ul><li>Good for small groups </li></ul><ul><li>Easy to complete </li></ul><ul><li>Accuracy problems due to social desirability bias </li></ul><ul><li>Not suitable for children under 10 or old adults due to cognitive limitations </li></ul><ul><li>High participant burden </li></ul><ul><li>Medium - high reactivity </li></ul>
  23. 24. Direct Observation <ul><li>Involves watching people objectively and noting specific behaviours and activities they are participating in </li></ul><ul><li>Commonly used with children </li></ul>
  24. 25. Considerations Advantages Disadvantages <ul><li>Can capture both qualitative and quantitative information </li></ul><ul><li>Quick and easy for small - medium sized studies </li></ul><ul><li>Can collect contextual information </li></ul><ul><li>Useful in community, school and workplace settings </li></ul><ul><li>Difficult with large groups </li></ul><ul><li>Time-intensive and labour-intensive </li></ul><ul><li>Obtrusive </li></ul><ul><li>High reactivity </li></ul>
  25. 26. Reducing Reactivity <ul><li>Repeated visits reduce the impact of the observer as subjects accustom to her/him </li></ul><ul><li>Observer subjects when they are unaware </li></ul><ul><li>Do not state the purpose of observer presence or conceal the real reason </li></ul>
  26. 27. Pedometers <ul><li>Worn on the hip and assess the number of steps a person takes by responding to vertical forces </li></ul><ul><li>10000 steps per day is considered as enough physical activity </li></ul><ul><li>Some pedometers measure many dimensions, but they are expensive </li></ul>
  27. 28. Considerations Advantages Disadvantages <ul><li>Inexpensive </li></ul><ul><li>Small, lightweight, non-invasive </li></ul><ul><li>Easy to administer for large groups </li></ul><ul><li>Objective measure of most common activity (walking) </li></ul><ul><li>Can promote behavioural change </li></ul><ul><li>Do not measure frequency, intensity or duration </li></ul><ul><li>Do not take into account body size and speed of locomotion </li></ul><ul><li>Cannot be used for activities such as swimming and upper body activities </li></ul><ul><li>Do not provide information about type </li></ul>
  28. 29. Accelerometers <ul><li>Worn at the waist or wrist </li></ul><ul><li>Record body motion over time </li></ul><ul><li>Good alternative to self-reports for kids </li></ul>
  29. 30. Considerations Advantages Disadvantages <ul><li>Provides information on intensity, frequency and duration </li></ul><ul><li>Non-invasive, small and lightweight </li></ul><ul><li>Low subject burden </li></ul><ul><li>Minute by minute data </li></ul><ul><li>Simple, quick data collection </li></ul><ul><li>Expensive so not suitable for large groups </li></ul><ul><li>Does not provide type or contextual information </li></ul><ul><li>Cannot be worn during aquatic-based activities </li></ul><ul><li>Requires knowledge to administer </li></ul>
  30. 31. Comparison of Measures Frequency Intensity Duration Type Context Cost Reactivity Recall Subjective ✓ ✓ ✓ ✓ ✓ Low None Diary/log Subjective ✓ ✓ ✓ ✓ ✓ Low High Direct observation Objective ✓ ✓ ✓ ✓ ✓ Moderate High Pedometer Objective ✕ ✕ ✕ ✕ ✕ Low Moderate Accelerometer Objective ✓ ✓ ✓ ✕ ✕ High Low
  31. 32. For more presentations visit the website