Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Measurement Challenges   in Physical ActivityUlf EkelundDepartment of Sport Science, Norwegian School of SportSciences, Os...
DEFINITIONS     Physical Activity “any bodily movement by skeletal muscles     resulting in an increase in energy expendit...
Sedentary behaviourSedentary is defined as “any waking behaviour characterized by an energyexpenditure ≤1.5 METs while in ...
CHALLENGE 1; Physical Activity isa complex behaviourType  Type or mode of activity refers to the different specific activi...
CHALLENGE 2; Physical Activity ishighly variable
CHALLENGE 3; All measurementsare associated with error
Why bother about accuracyand precision? • To clarify which dimension of physical activity is   more important for a specif...
Measuring Physical Activity –Levels of Sophistication
Strengths and limitations with Self-Report Methods • Detailed info about PA types and domains (e.g.   TV-time; transport) ...
• January 1997-December 2011• 31 studies testing 34 newly developed PAQs• 65 studies testing 96 existing PAQs• Criterion: ...
Self-reports predict morbidity        and mortality!
Global self-reports: “CambridgeIndex” derived from Short EPIC                              Leisure time physical activity ...
RIGOROUS VALIDATION PROCESS(InterAct Consortium, Euro J Epidemiol, 2012)
(Ekelund et al, AJCN 2011)
(InterAct Consortium, Diabetologia, 2012)
Objective monitoring; A plethoraof Monitors
What is an objective method?• Numerical measurement of a physiological / biomechanical  (i.e. acceleration) variable• Used...
Assessment of body movementbased on accelerometry                                                                         ...
Limitations with Accelerometryand Heart Rate monitoring• Accelerometry has                                                ...
What have we learnt from objective monitoring?
The importance of the total volumeof activity                            (Manini et al, JAMA 2006)
Population Levels of activity                                                                                          %AU...
(Assah et al, Diabetes Care, 2011)
Which sub-component is ofimportance?                            (Ekelund et al, JAMA 2012)
Summary • Self-reported methods should be validated and calibrated   in the specific study population • PA assessed by sel...
AcknowledgementsDepartment of Sport Medicine, Oslo, Norway •   The Lancet Physical Activity WritingSigmund A Andersen     ...
Upcoming SlideShare
Loading in …5
×

Ekelund opac2013

1,433 views

Published on

Published in: Technology, Business
  • Be the first to comment

Ekelund opac2013

  1. 1. Measurement Challenges in Physical ActivityUlf EkelundDepartment of Sport Science, Norwegian School of SportSciences, Oslo, NorwayandMRC Epidemiology Unit, Cambridge, UKIASO and WCRF HOT TOPIC CONFERENCE, LONDON April 16th 2013I have no conflicts of interest to declare
  2. 2. DEFINITIONS Physical Activity “any bodily movement by skeletal muscles resulting in an increase in energy expenditure” Exercise “a subset of physical activity which is structured, repetitive and done with purpose (e.g. improve health)” Fitness is “a set of attributes influenced by but distinct from physical activity and exercise” Health-related fitness and performance related fitness (Adapted from Caspersen et al, 1985)
  3. 3. Sedentary behaviourSedentary is defined as “any waking behaviour characterized by an energyexpenditure ≤1.5 METs while in a sitting or reclining posture”Physical inactivity describe those who are “performing insufficient amounts ofMVPA” (i.e., not meeting specified physical activity guidelines) (Appl Physiol Nutr Metab 2012;37:540–542)
  4. 4. CHALLENGE 1; Physical Activity isa complex behaviourType Type or mode of activity refers to the different specific activities a person is engaged in (e.g. standing, walking, cycling, car driving, etc)Domain The context in which activity takes place (e.g. leisure, work, transport, household)Frequency Number of activity bouts during a specific time periodDuration Time (sec, min, hours) of participation in a single bout of activityIntensity The physiological effort associated with participating in activityVolume The integrated product of frequency, duration and intensity
  5. 5. CHALLENGE 2; Physical Activity ishighly variable
  6. 6. CHALLENGE 3; All measurementsare associated with error
  7. 7. Why bother about accuracyand precision? • To clarify which dimension of physical activity is more important for a specific health outcome • To make cross-cultural comparisons • To monitor temporal trends within populations • To assess the effect of interventions • To control habitual physical activity in trials • To improve statistical power and decrease sample size (Wareham & Rennie, IJO 1998)
  8. 8. Measuring Physical Activity –Levels of Sophistication
  9. 9. Strengths and limitations with Self-Report Methods • Detailed info about PA types and domains (e.g. TV-time; transport) • Cost-effective • Fairly high precision (reproducibility) (r>0.7) • Fairly low accuracy (r=0.3 to 0.4) • Low accuracy for specific domains (e.g. domestic chores) • Low accuracy for light intensity PA • Low accuracy for total PA
  10. 10. • January 1997-December 2011• 31 studies testing 34 newly developed PAQs• 65 studies testing 96 existing PAQs• Criterion: Accelerometry, DLW, HR, HR+Acc, Pedometer• Median reliability (ICC): 0.62-0.71 (existing) 0.74-0.76 (new)• Median validity (r): 0.30-0.39 (existing) 0.25-0.41 (new)• Conclusion: Newly developed PAQs do not appear to perform substantially better than existing PAQs in terms of reliability and validity. Future PAQ studies should include measures of absolute validity (mean bias) and the error structure of the instrument. (Helmerhorst et al, IJBNPA 2012)
  11. 11. Self-reports predict morbidity and mortality!
  12. 12. Global self-reports: “CambridgeIndex” derived from Short EPIC Leisure time physical activity (Duration of sport and cycling in hrs/wk) Work activity No ≤3.5 >3.5 and ≤7.0 > 7.0 Moderately Moderately Sedentary Inactive inactive active Active Moderately Moderately Standing inactive active Active Active Moderately Manual active Active Active Active Heavy manual Active Active Active Active
  13. 13. RIGOROUS VALIDATION PROCESS(InterAct Consortium, Euro J Epidemiol, 2012)
  14. 14. (Ekelund et al, AJCN 2011)
  15. 15. (InterAct Consortium, Diabetologia, 2012)
  16. 16. Objective monitoring; A plethoraof Monitors
  17. 17. What is an objective method?• Numerical measurement of a physiological / biomechanical (i.e. acceleration) variable• Used to quantify one or more aspect of physical activity: • Physical Activity Energy expenditure (PAEE) • Duration of activity • Intensity of activity • Frequency of activity • Presence or lack of activity • Body positions • Sedentary time • (Types of activity – pattern recognition) • (Location of physical activity – GPS)• No misclassification due to reporting bias• Increased precision and accuracy of duration, intensity and frequency of PA and sedentary time
  18. 18. Assessment of body movementbased on accelerometry Actigraph counts (hip) or Actiheart counts (chest)• Measures acceleration (3 axis) 16000• Non-linear relationship between 12000 acc and EE during specific 8000 activities pending on placement 4000 of the monitor• May be sensible to external 2.5 5 7.5 10 12.5 Treadmill speed [km/hr] vibrations Acceleration [m/s2] measured by Actigraph (hip) or Actiheart (chest) 12.5• The output is usually an arbitrary unit (counts) which 10 differs between monitor brands 7.5• ”Leveling off” effect at high 5 intensities of locomotion 2.5 2.5 5 7.5 10 12.5 Treadmill speed [km/hr]
  19. 19. Limitations with Accelerometryand Heart Rate monitoring• Accelerometry has 12000 limitations (e.g. bicycling, CSA_All (counts·min-1) 10000 carrying goods, walking 8000 * uphill etc.) 6000• Heart rate monitoring has * limitations (e.g. elevated HR 4000 due to stress and 2000 environmental factors) 4 6 8 10 12 14 16 18• Measurement errors from -1 Speed (km·h ) the two methods are not (Brage et al, MSSE, 2003) positively correlated• Combination of movement and HR-monitoring may overcome these limitations (Adopted from Åstrand et al. 2002)
  20. 20. What have we learnt from objective monitoring?
  21. 21. The importance of the total volumeof activity (Manini et al, JAMA 2006)
  22. 22. Population Levels of activity %AUTHOR COUNTRY Mean (95% CI) WeightmenHagstromer Swe 36.00 (34.00, 38.00) 10.28Hagstromer US 33.00 (31.00, 36.00) 6.58Baptista Portugal 37.50 (35.00, 40.00) 6.58Hansen Norway 35.40 (34.20, 36.60) 28.56Subtotal (I-squared = 54.3%, p = 0.087) 35.48 (34.59, 36.37) 52.01womenHagstromer Swe 32.00 (29.00, 34.00) 6.58Hagstromer US 19.00 (17.00, 21.00) 10.28Baptista Portugal 44.60 (41.00, 49.00) 2.57Hansen Norway 32.80 (31.60, 34.00) 28.56Subtotal (I-squared = 98.4%, p = 0.000) 30.37 (29.44, 31.29) 47.99Heterogeneity between groups: p = 0.000Overall (I-squared = 97.3%, p = 0.000) 33.03 (32.38, 33.67) 100.00 0 10 20 30 40 50 (Hallal et al, Lancet 2012)
  23. 23. (Assah et al, Diabetes Care, 2011)
  24. 24. Which sub-component is ofimportance? (Ekelund et al, JAMA 2012)
  25. 25. Summary • Self-reported methods should be validated and calibrated in the specific study population • PA assessed by self-report is associated with health outcomes – detailed dose-response associations difficult to assess • Objective monitoring is feasible in large scale epidemiological studies – greater detail of PA patterns; dose-response; cross-cultural comparisons; trials/interventions; reduce sample size; young people • Very large scale studies using objective monitoring is underway • Pattern recognition from raw acceleration appears possible
  26. 26. AcknowledgementsDepartment of Sport Medicine, Oslo, Norway • The Lancet Physical Activity WritingSigmund A Andersen GroupBjørge H Hansen • The International Accelerometer DatabaseMaria Hildebrand Partners (ICAD)Elin Kolle • The European Youth Heart Study PartnersMRC Epidemiology Unit Cambridge, UK (EYHS)Felix Assah • The EPIC StudySoren Brage • The InterAct StudyPaul CollinsKirsten CorderTricia PetersCharlotte RidgwayVincent van HeesNick WarehamKate WestgateKatrien Wijndaele

×