PURPOSE: To assess the convergent validity of body worn wearable camera (WC) still-images (IMGs) for determining posture compared with activPAL (AP) classifications. METHODS: Participants (n=16, mean age 46.7±23.8yrs, 9F) wore an Autographer WC above the xyphoid process and an AP during three, 2hr free-living visits. IMGs were captured on average 8.47 seconds apart and were annotated with output consisting of events, transitory states, unknown and gaps. Events were annotations that matched AP classifications (sit, stand and move) consisting of at least 3 IMGs, transitory states were posture annotations fewer than 3 IMGs, unknown were IMGs that could not be accurately classified, and gaps were time between annotations. For analyses, annotation and AP output were converted to one-sec epochs and matched second-by-second. Total and average length of visits and events are reported in minutes. Bias and 95% CIs for event posture times from IMGs to AP posture times were calculated to determine accuracy and precision. Confusion matrices using total AP posture times were computed to determine misclassification. RESULTS: 43 visits were analyzed with a total visit and event time of 5027.73 and 4237.23 minutes and average visit and event lengths being 116.92 and 98.54 minutes, respectively. Bias was not statistically significant for sitting but significant for standing and movement (0.84, -6.87 and 6.04 minutes). From confusion matrices, IMGs correctly classified sitting, standing and movement 85.69%, 54.87%, and 69.41% of total AP time, respectively. CONCLUSION: WC IMGs provide a good estimation of overall sitting time but underestimate standing and overestimate movement time. Future work is warranted to improve posture classifications and examine IMG accuracy and precision in assessing activity type behaviors.
PURPOSE: To assess the convergent validity of body worn wearable camera (WC) still-images (IMGs) for determining posture compared with activPAL (AP) classifications. METHODS: Participants (n=16, mean age 46.7±23.8yrs, 9F) wore an Autographer WC above the xyphoid process and an AP during three, 2hr free-living visits. IMGs were captured on average 8.47 seconds apart and were annotated with output consisting of events, transitory states, unknown and gaps. Events were annotations that matched AP classifications (sit, stand and move) consisting of at least 3 IMGs, transitory states were posture annotations fewer than 3 IMGs, unknown were IMGs that could not be accurately classified, and gaps were time between annotations. For analyses, annotation and AP output were converted to one-sec epochs and matched second-by-second. Total and average length of visits and events are reported in minutes. Bias and 95% CIs for event posture times from IMGs to AP posture times were calculated to determine accuracy and precision. Confusion matrices using total AP posture times were computed to determine misclassification. RESULTS: 43 visits were analyzed with a total visit and event time of 5027.73 and 4237.23 minutes and average visit and event lengths being 116.92 and 98.54 minutes, respectively. Bias was not statistically significant for sitting but significant for standing and movement (0.84, -6.87 and 6.04 minutes). From confusion matrices, IMGs correctly classified sitting, standing and movement 85.69%, 54.87%, and 69.41% of total AP time, respectively. CONCLUSION: WC IMGs provide a good estimation of overall sitting time but underestimate standing and overestimate movement time. Future work is warranted to improve posture classifications and examine IMG accuracy and precision in assessing activity type behaviors.
Authors: Barbara E Ainsworth; William L Haskell; Stephen D Herrmann; Nathanael Meckes; David R Bassett; Catrine Tudor-Locke; Jennifer L Greer; Jesse Vezina; Melicia C Whitt-Glover; Arthur S Leon Journal: Med Sci Sports Exerc Date: 2011-08 Impact factor: 5.411
Authors: Sarah Kozey-Keadle; Amanda Libertine; Kate Lyden; John Staudenmayer; Patty S Freedson Journal: Med Sci Sports Exerc Date: 2011-08 Impact factor: 5.411
Authors: Aiden R Doherty; Steve E Hodges; Abby C King; Alan F Smeaton; Emma Berry; Chris J A Moulin; Siân Lindley; Paul Kelly; Charlie Foster Journal: Am J Prev Med Date: 2013-03 Impact factor: 5.043
Authors: Gillian O'Loughlin; Sarah Jane Cullen; Adrian McGoldrick; Siobhan O'Connor; Richard Blain; Shane O'Malley; Giles D Warrington Journal: Am J Prev Med Date: 2013-03 Impact factor: 5.043
Authors: Jacqueline Kerr; Simon J Marshall; Suneeta Godbole; Jacqueline Chen; Amanda Legge; Aiden R Doherty; Paul Kelly; Melody Oliver; Hannah M Badland; Charlie Foster Journal: Am J Prev Med Date: 2013-03 Impact factor: 5.043