scholarly journals Validation of Wearable Camera Still Images to Assess Posture in Free-Living Conditions

2021 ◽  
Vol 4 (1) ◽  
pp. 47-52
Author(s):  
Julian Martinez ◽  
Autumn E. Decker ◽  
Chi C. Cho ◽  
Aiden Doherty ◽  
Ann M. Swartz ◽  
...  
Keyword(s):  
Convergent Validity ◽  
Average Length ◽  
Sitting Time ◽  
Free Living ◽  
Still Images ◽  
Event Time ◽  
Wearable Camera ◽  
Accuracy And Precision ◽  
Future Work ◽  
Confusion Matrices

Purpose: To assess the convergent validity of body-worn wearable camera still images (IMGs) for determining posture compared with activPAL (AP) classifications. Methods: The participants (n = 16, mean age 46.7 ± 23.8 years, 9 F) wore an Autographer wearable camera and an AP during three 2-hr free-living visits. IMGs were on average 8.47 s apart and were annotated with output consisting of events, transitory states, unknown, and gaps. The events were annotations that matched AP classifications (sit, stand, and move), consisting of at least three IMGs; the transitory states were posture annotations fewer than three IMGs; the unknowns were IMGs that could not be accurately classified; and the gaps were the time between annotations. For the analyses, the annotation and AP output were converted to 1-s epochs. The total and average length of visits and events were reported in minutes. Bias and 95% confidence intervals for event posture times from IMGs to AP were calculated to determine accuracy and precision. Confusion matrices using total AP posture times were computed to determine misclassification. Results: Forty-three visits were analyzed, with a total visit and event time of 5,027.73 and 4,237.23 min, respectively, and the average visit and event lengths being 116.92 and 98.54 min, respectively. Bias was not statistically significant for sitting, but was significant for standing and movement (0.84, −6.87, and 6.04 min, respectively). From confusion matrices, IMGs correctly classified sitting, standing, and movement (85.69%, 54.87%, and 69.41%, respectively) of total AP time. Conclusion: Wearable camera IMGs provide a good estimation of overall sitting time. Future work is warranted to improve posture classifications and examine the validity of IMGs in assessing activity-type behaviors.

Statistical analysis of nematode counts from interlaboratory proficiency tests

Nematology ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 229-243 ◽  
Author(s):  
Wim Van Den Berg ◽  
Olaf Hartsema ◽  
Loes J.M.F. Den Nijs
Keyword(s):  
Statistical Analysis ◽  
Proficiency Test ◽  
Meta Analysis ◽  
Proficiency Tests ◽  
Free Living ◽  
Accuracy And Precision ◽  
Mean And Variance ◽  
The Mean ◽  
Interaction Variance

A series of proficiency tests on potato cyst nematode (PCN; ) and free-living stages of Meloidogyne and Pratylenchus () were investigated to determine the accuracy and precision of the nematode counts and to gain insights into possible trends and potential improvements. In each test, each participating laboratory received ten samples of soil collected from naturally infested fields and well mixed before distribution. The variance between the counts from the ten samples, estimated per test and laboratory, was constant for PCN cysts and free-living stages of Meloidogyne spp. and Pratylenchus spp. during the period monitored. However, during the initial years, the variance between the samples showed a downward trend for PCN living juveniles. The variance between the laboratories, estimated per test, was constant for PCN cysts over the period 1994-2010. For PCN living juveniles the variance between laboratory means declined from 1994-2000 and from 2000 it was more or less constant, which coincided with the introduction of a well-described new methodology. For Meloidogyne spp. and Pratylenchus spp., from 1998-2005 the variance between laboratory means was more or less constant or increased. From 2006, all participating laboratories incubated the organic matter and the variance between the laboratories was stable and below the levels observed during 2003-2005. After discarding data from initial years with unstable variances of the nematode counts, a meta-analysis was carried out on the remaining data using HGLMs to model the mean and variance of the counts simultaneously. The within-laboratory variance for the ten samples and the interaction variance of test and laboratory were estimated and combined to percentage coefficient of variation (%CV) per laboratory. For PCN cysts, %CV per laboratory ranged from 12.6 to 41.6 and for PCN juveniles in sandy soil from 24.4 to 67.4 and in loamy soil from 37.9 to 102.0. For Meloidogyne spp., %CV ranged from 53.2 to 84.4 and for Pratylenchus spp. from 24.3 to 90.6. The quality of a proficiency test is largely defined by random distribution of the nematodes over the samples allocated, statistical analysis of the data and communication of the results to participating laboratories. This study provides insights into the accuracy and precision at laboratories in recent years and the effect of concerted actions during the period in which the proficiency tests were conducted.

scholarly journals Monitoring of Sitting Postures With Sensor Networks in Controlled and Free-living Environments: Systematic Review

10.2196/21105 ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. e21105
Author(s):  
Arpita Mallikarjuna Kappattanavar ◽  
Nico Steckhan ◽  
Jan Philipp Sachs ◽  
Harry Freitas da Cruz ◽  
Erwin Böttinger ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Pressure Sensors ◽  
Ground Truth ◽  
Living Environment ◽  
Measurement Unit ◽  
Future Research ◽  
Free Living ◽  
Medium Quality ◽  
Underlying Causes ◽  
Future Work

Background A majority of employees in the industrial world spend most of their working time in a seated position. Monitoring sitting postures can provide insights into the underlying causes of occupational discomforts such as low back pain. Objective This study focuses on the technologies and algorithms used to classify sitting postures on a chair with respect to spine and limb movements. Methods A total of three electronic literature databases were surveyed to identify studies classifying sitting postures in adults. Quality appraisal was performed to extract critical details and assess biases in the shortlisted papers. Results A total of 14 papers were shortlisted from 952 papers obtained after a systematic search. The majority of the studies used pressure sensors to measure sitting postures, whereas neural networks were the most frequently used approaches for classification tasks in this context. Only 2 studies were performed in a free-living environment. Most studies presented ethical and methodological shortcomings. Moreover, the findings indicate that the strategic placement of sensors can lead to better performance and lower costs. Conclusions The included studies differed in various aspects of design and analysis. The majority of studies were rated as medium quality according to our assessment. Our study suggests that future work for posture classification can benefit from using inertial measurement unit sensors, since they make it possible to differentiate among spine movements and similar postures, considering transitional movements between postures, and using three-dimensional cameras to annotate the data for ground truth. Finally, comparing such studies is challenging, as there are no standard definitions of sitting postures that could be used for classification. In addition, this study identifies five basic sitting postures along with different combinations of limb and spine movements to help guide future research efforts.

scholarly journals Validation of the IPAQ Against Different Accelerometer Cut-Points in Older Cancer Survivors and Adults at Risk of Cancer

2018 ◽  
Vol 26 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Liane S. Lewis ◽  
James Hernon ◽  
Allan Clark ◽  
John M. Saxton
Keyword(s):  
Convergent Validity ◽  
Leisure Time ◽  
Sedentary Time ◽  
Free Living ◽  
Cut Points ◽  
Movement Data ◽  
Males And Females ◽  
Accelerometer Cut Points ◽  
Risk Of Cancer ◽  
Walking Time

The present study investigated the convergent validity of an interview-administered IPAQ long version (IPAQ-L) in an older population by comparison with objective accelerometry movement data. Data from 52 participants (mean age 67.9 years, 62% male) were included in the analysis. Treadmill derived (TM-ACC: 1,952–5,724 cpm) and free-living physical activity (PA) derived (FL-ACC: 760–5,724 cpm) accelerometer cut-points were used as criterion. IPAQ-L measures (total PA, leisure-time, walking-time, sedentary time) were significantly correlated with accelerometry (P ≤ .05). Differences in sex were observed. Bland-Altman Limits of Agreement analysis showed that the IPAQ-L overestimated PA in relation to accelerometry. Our results show that an interview-administered IPAQ-L shows low to moderate convergent validity with objective PA measures in this population but there may be differences between males and females which should be further investigated.

Convergent Validity of 3 Low Cost Motion Sensors With the ActiGraph Accelerometer

2010 ◽  
Vol 7 (5) ◽  
pp. 662-670 ◽  
Author(s):  
James J. McClain ◽  
Teresa L. Hart ◽  
Renee S. Getz ◽  
Catrine Tudor-Locke
Keyword(s):  
Physical Activity ◽  
Convergent Validity ◽  
Lower Cost ◽  
Low Cost ◽  
Assessment Instruments ◽  
Motion Sensors ◽  
Activity Time ◽  
Free Living ◽  
Time Estimates ◽  
Actigraph Accelerometer

Background:This study evaluated the utility of several lower cost physical activity (PA) assessment instruments for detecting PA volume (steps) and intensity (time in MVPA or activity time) using convergent methods of assessment.Methods:Participants included 26 adults (9 male) age 27.3 ± 7.1 years with a BMI of 23.8 ± 2.8 kg/m2. Instruments evaluated included the Omron HJ-151 (OM), New Lifestyles NL-1000 (NL), Walk4Life W4L Pro (W4L), and ActiGraph GT1M (AG). Participants wore all instruments during a laboratory phase, consisting of 10 single minute treadmill walking bouts ranging in speed from 40 to 112 m/min, and immediate following the laboratory phase and during the remainder of their free-living day (11.3 ± 1.5 hours). Previously validated AG MVPA cutpoints were used for comparison with OM, NL, and W4L MVPA or activity time outputs during the laboratory and free-living phase.Results:OM and NL produced similar MVPA estimates during free-living to commonly used AG walking cutpoints, and W4L activity time estimates were similar to one AG lifestyle cutpoint evaluated.Conclusion:Current findings indicate that the OM, NL, and W4L, ranging in price from $15 to $49, can provide reasonable estimates of free-living MVPA or activity time in comparison with a range of AG walking and lifestyle cutpoints.

Convergent and criterion-related validity of the short form of the International Physical Activity and the Incidental and Planned Physical Activity Questionnaires in people with multiple sclerosis

2021 ◽  
pp. 1-10
Author(s):  
Hanan Khalil ◽  
Aseel Aburub ◽  
Saddam F. Kanaan ◽  
Alham AlSharman ◽  
Shada Khazaaleh ◽  
...  
Keyword(s):  
Physical Activity ◽  
Multiple Sclerosis ◽  
Convergent Validity ◽  
International Physical Activity Questionnaire ◽  
Sedentary Time ◽  
Short Form ◽  
Sitting Time ◽  
Activity Questionnaires ◽  
Activity Questionnaire

BACKGROUND: Assessing physical activity (PA) in people with multiple sclerosis (PwMS) is essential to follow-up the recommended PA level. The International Physical Activity Questionnaire (IPAQ) and the Incidental and Planned Exercise Questionnaire (IPEQ) have been widely used, but their validity has not been investigated previously in PwMS. OBJECTIVE: This study aimed to assess the convergent and criterion validity of the IPAQ and the IPEQ in PwMS. METHODS: 50 PwMS were asked to wear an Actigraph for seven days and to fill the IPAQ and IPEQ. Sedentary, moderate (MPA), vigorous (VPA) and moderate to vigorous PA (MVPA) levels were recorded. RESULTS: Significant correlations were found between sitting time as reported by IPAQ and sedentary time as recorded by Actigraph (r = 0.41, p = 0.003), VPA by IPAQ and VPA as recorded by Actigraph (r = 0.46, p = 0.001), and MVPA by IPAQ and MVPA by Actigraph (r = 0.36, p = 0.011). IPEQ showed poor both criterion and convergent validity when compared to the Actigraph. Both IPAQ and IPEQ overestimate the intensities of PA for all the derived parameters. CONCLUSIONS: Findings of this study are important as they suggest that IPAQ in particular had convergent validity when compared to Actigraph data, but still had the problem of overestimating PA levels.

Descriptive Epidemiology of Interruptions to Free-Living Sitting Time in Middle-Age and Older Adults

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Jennifer Blankenship ◽  
Elisabeth A. H. Winkler ◽  
Genevieve N. Healy ◽  
Paddy C. Dempsey ◽  
John Bellettiere ◽  
...  
Keyword(s):  
Older Adults ◽  
Middle Age ◽  
Sitting Time ◽  
Descriptive Epidemiology ◽  
Free Living
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