Physical Activity Assessment Techniques

1. Physical Activity Assessment Techniques Validity, Reliability, Tools

2. Introduction • http://abcnews.go.com/WNT/video/america-lags-walking-exercise-obesity-weight-11808653

3. Where are we? • You should be familiar with the PA guidelines and the ways PA can be quantified • The purpose of this lecture is to help you understand and identify multiple methods to quantify PA so that you can determine if your client meets the guidelines (and prescribe PA) • We must determine what makes one assessment technique “better” than another

4. Measurement Issues • How can one monitor be “better” than another? • Consider: • Sensitivity to change (precision) • Reactivity • Comfort to respondent (feasibility) • Cost of administration (feasibility) • The above can be considered your preference • Two considerations are far more important – validity and reliability

5. + + + + + + + + + + + + + + + + + + + + + + + Validity + Reliability Valid + Reliable Reliable w/ poor Validity Poor

6. Statistical Note • Reliability and Validity are generally expressed as correlation coefficients • Range from -1 to +1 • Stronger (and better) relationships are seen closer to 1 • A correlation of 0.00 basically means there is no relationship (poor reliability, poor validity)

7. Recap of Measurement Issues • Evaluate each measurement tool based on these concepts • Sensitivity to change (precision) • Reactivity • Comfort to respondent (feasibility) • Cost of administration (feasibility) • Validity (accuracy) • Reliability (consistency)

8. Physical Activity Assessment Tools:Figuring Out Energy Expenditure and Minutes of Activity

9. Activity Monitoring Tools • Currently, there is a strong relationship between the feasibility of a PA assessment tool and it’s validity – and that relationship is in the wrong direction • We’ll tackle these different methods in order of weakest validity to strongest • Keep in mind that the tool you select is based on what you want to know and how you are going to use it!!

10. Questionnaire Diary Pedometers HR monitors Accelerometers Direct observation I. calorimetery DLW Physical Activity Assessments (Feasibility-Validity) Feasibility Validity

11. Self Report Tools • Subjective assessment tools are at the mercy of those providing the information • Self-Report Instruments • Recall • Diaries/Logs • Questionnaire • These tools require the client identify their own PA levels (to some degree) • Use time and intensity of PA to further extrapolate to EE

12. Recall • Example: 7-Day PAR (Physical Activity Recall) • One week period, interview based, participant recalls: • Sleep • Moderate (minutes) • Hard (minutes) • Very Hard (minutes) • Minutes working on strength/flexibility • Note: Interviewer script, memory cues

13. Diary/Log • Instead of having the subject recall activity, perhaps validity/reliability can be improved by having them keep constant measurement? • Bouchard 3-Day Physical Activity Diary • Minutes of PA and EE • Note: • Short intervals, MET-reference guide

14. Questionnaire • Questionnaires do not ask clients to recall a specific time, nor do they use a continuous log • Simply ask the client how active they are normally • Some are more detailed than others • Example: Godin Leisure-Time PA Questionnaire

15. Other Self-Report Instruments • Numerous examples: • ACLS Questionnaire • Paffenbarger Physical Activity Recall • CARDIA Physical Activity History • Modifiable Physical Activity Questionnaire • Yale Physical Activity Survey • Historical Physical Activity Questionnaire • NHANES • Etc…

16. Other Self-Report Instruments • Numerous examples: • ACLS Questionnaire • Paffenbarger Physical Activity Recall • CARDIA Physical Activity History • Modifiable Physical Activity Questionnaire • Yale Physical Activity Survey • Historical Physical Activity Questionnaire • NHANES • Etc…

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18. Other Self-Report Instruments • Numerous examples: • ACLS Questionnaire • Paffenbarger Physical Activity Recall • CARDIA Physical Activity History • Modifiable Physical Activity Questionnaire • Yale Physical Activity Survey • Historical Physical Activity Questionnaire • NHANES • Etc…

19. NHANES • For NHANES, participants are asked very specific questions on about 10 physical activities (like walking, cycling, aerobics, playing sports, etc…) • “On how many of the previous 30 days did you participate in ________?” • “On average, when you participated in _______, how long did you do this activity?”

20. Remember this? • Data show that nearly four in ten (38.3 percent) adults reported no participation in leisure-time physical activity. Does knowing how PA was assessed change your perspective on inactivity in the US?

21. Self-Report: Validity and Reliability • In general, reliability of self-report measures are low-moderate • Low to non-existent reliability for light activity • High reliability for vigorous activity • In general, validity of self-report measures are moderate for energy expenditure and low for minutes of physical activity • Godin ~ 0.30-0.40 compared with kcal/day

22. Self-Report • Strengths: • Low time, cost, work commitment (feasible) • When used with MET-compendium, both energy expenditure and minutes of activity can be identified • Can identify time-frame easily (past month, year, lifetime, etc…) • Allows determination of the “dimensions” of physical activity with both qualitative and quantitative information

23. Self-Report • Limitations: • Biased towards structured, high intensity (exercise) • Low-moderate validity and reliability • Not good for estimating minutes of PA (alright at total EE) • Participant ignorance (what’s moderate again?) • Certain groups may have poor recall ability (children) • Potential content validity problems (participants may misinterpret questions) • Social desirability

24. Physical Activity Assessment Techniques Gadgets

25. Questionnaire Diary Pedometers HR monitors Accelerometers Direct observation I. calorimetery DLW Physical Activity Assessments (Feasibility-Validity) Feasibility Validity

26. Pedometers • Simple pedometers are the first objective monitoring tool we will discuss • Provide information on ambulatory physical activity, priced between $20-$300 • Walking: • Is the #1 ranked physical activity in the US • Accounts for a major portion of total daily activity • Confers substantial health benefits

27. Simple Question • How valid do you think a pedometer is? • High validity in measuring steps, but… • Moderate validity in measuring physical activity (0.30-0.50) • Pedometers assess steps/day, not minutes of activity, or intensity, or energy expenditure • Construct Validity with minutes/EE • Raw Volume of PA

28. Pedometers • Although this is a limitation, pedometers are good at what they are supposed to do • Due to their cost and simplicity, they are widely studied and used • We even have separate recommendations for pedometers – and you all probably know it!

29. Target Steps/day • Hanato (1997), in a Japanese sample, found that subjects getting 10,000 steps/day were more likely to have lower blood pressure and %BF • This “10,000” was pulled from thin air • Nice round number, easily remembered, easily interpretable to clients (not like METs or “moderate” activity • In Japan, the term for pedometer is manpo-kei, which is literally translated to “10,000 step meter”

30. Versus the 30 minutes (old rec) • Welk et al. found that 73% of subjects that averaged >10,000 steps/day performed >30 minutes of moderate activity • This is due to a moderate construct validity between steps/day and minutes of activity • Overall, it appears that getting about 10,000 is somewhere close to the recommended amount of PA

31. Pedometer-Specific Groups • Pedometers alone can be used to categorize clients into physical activity groups: • Sedentary: <5000 steps/day • Low Active: 5000-7499 steps/day • Somewhat Active: 7500-9,999 steps/day • Active: 10,000-12,499 steps/day • Highly Active: 12,500 steps/day • These targets can be used to motivate clients outside of the gym

32. Old-Order Amish • In 2004, Bassett completed a study analyzing the steps/day (physical activity) of an old-order Amish community • Besides shaming typical US Adults, it demonstrates what physical activity levels may have looked like 150 years ago • Keep in mind that ~ 10,000 steps indicates they meet US PA guidelines and 12,500 steps is Highly Active

35. Self-Report • US Adult Guidelines: Minimum 150 min. of moderate activity or 75 min. vigorous Amish Men: 0% Obesity, Women: 9% Obesity

36. Pedometer • Strengths: • Objective • Inexpensive and easy to use • Moderate Validity • Interpretable • Specific targets exist for prescription • Limitations: • Doesn’t capture all PA • Not direct minutes of PA or EE • Reactivity?

37. Questionnaire Diary Pedometers HR monitors Accelerometers Direct observation I. calorimetery DLW Physical Activity Assessments (Feasibility-Validity) Feasibility Validity

38. Accelerometer • Due to the lack of “other” activities being captured by the pedometer, accelerometers have been created • Walking and running 20 steps are equally weighted in pedometry • Accelerometers can tell the difference

39. Detection of acceleration: Piezo-electric bender element is sensitive to acceleration - transducer bends and a proportionate electrical charge created Amount of movement is summed over time Movement is reported in counts/time Real time recording allow temporal patterns to be observed Instrumentation / Principles

40. Data Output Whole-Day Accelerometry Adult Walk Walk Lunch TV Sleep Off

41. Outcome Measures • Average movement count (total activity) • Counts/min • Equations to predict EE from movement counts • Kcal/min or METS • Time spent being active • Number of minutes above threshold (cut point derived from regression equation) • Number of bouts of activity • Number of times with continuous movement greater than threshold • Ie – were they active for 10 continuous minutes?

42. Measurement Issues Accelerometry • Validity • Indirect calorimetry lab r = 0.80 to 0.90 lab • Indirect calorimetry field r = 0.40 to 0.60 • Reliability • Inter-instrument reliability consistently high (r > 0.90) • Sensitive to change • Non-reactive • Acceptable to subject • Acceptable cost? (units $200 to 500, interface $500)

43. Vigorous Activity counts Moderate Light VO2 or energy expenditure Development of Prediction Equations and Activity “Cutpoints” Characterize relationship between movement counts oxygen consumption

44. Application of Count Thresholds for Processing Accelerometer Data If a threshold accurately defines a particular level of activity, the time spent in activity can be determined.

45. NHANES • Recall that about 40% of US adults report no leisure-time activity • Based on what assessment of PA…? • NHANES recently introduced accelerometry into their survey • Objective assessment of PA • How many people “meet” guidelines?

46. Males, Moderate and Vigorous Activity x Age Group Remember: This is the MEAN or average minutes

47. Females, Moderate and Vigorous Activity x Age Group Remember: This is the MEAN or average minutes

49. How does that compare? • Approximately 5-10% of Americans meet or exceed the recommendation of 30 minutes of at least moderate activity on 5-7 days of the week • Objective vs Subjective methods of assessment

50. Limitations: • Accelerometers, while very good at what they do, are not without limitations: • Not sensitive some movements • Not sensitive to grade • Not sensitive to increased weight • Restricted to mainly ambulatory activity