Refining the accelerometric measurement of physical activity

Advances in electronic sensor technologies have led to the increased use of accelerometers for measuring physical activity and sedentary behaviours. Accelerometers overcome many of the inherent limitations of other measurement methods; for example, unlike self-reported instruments, accelerometers are free from random and systematic errors introduced by respondents and interviewers, cultural tradition, and language. However, accelerometers have their own set of limitations; for example, not all accelerometers are created equal and raw accelerometer data require significant data mining procedures in order to yield meaningful outcome variables. Therefore the overall purpose of this three study dissertation was to determine the impact accelerometer model has on the development of a comprehensive physical activity and sedentary behaviour profile and to design and apply novel profiling methods in an order to gain new insights into children’s physical activity. Study One Purpose: To determine which of the three most commonly used accelerometer models has the best intra- and inter-instrument reliability using a mechanical laboratory setup. Secondly, to determine the effect acceleration and frequency have on these reliability measures. Methods: Three experiments were performed. In the first, five each of the Actical, Actigraph, and RT3 accelerometers were placed on a hydraulic shaker plate and simultaneously accelerated in the vertical plane at varying accelerations and frequencies. Six different conditions of varying intensity were used to produce a range of accelerometer counts. Reliability was calculated using standard deviation, standard error of the measurement, coefficient of variation, and intraclass correlation coefficients. In the second and third experiment, 39 Actical and 50 Actigraph accelerometers were put through the same six conditions. Results: Experiment One showed poor reliability in the RT3 (intra- and inter-instrument CV > 40%). Experiments Two and Three clearly indicated that the Actical (CVintra = 0.5%; CVinter = 5.4%) was more reliable than the Actigraph (CVintra = 3.2%; CVinter = 8.6%). Variability in the Actical was negatively related to the acceleration of the condition while no relationship was found between acceleration and reliability in the Actigraph. Variability in the Actigraph was negatively related to the frequency of the condition while no relationship was found between frequency and reliability in the Actical. Conclusion: Of the three accelerometer models measured in this study, the Actical had the best intra- and inter-instrument reliability. However, discrepant trends in the variability of Actical and Actigraph counts across accelerations and frequencies preclude the selection of a ‘superior’ model. More work is needed to understand why accelerometers designed to measure the same thing, behave so differently. Study Two The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity/sedentary behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity and sedentary profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canada’s Physical Activity Guidelines. Recommendations for physical activity and sedentary profiling are provided and future research needs identified. Study Three Purpose: This study explored the influence of modernity on the physical activity behaviours (e.g. intensity and timing) of children. Methods: Children aged 8-13 years living a traditional lifestyle (Old Order Amish; OOA n=68, Old Order Mennonite; OOM n=120) were compared with children living a contemporary lifestyle (rural Saskatchewan; RSK n=132 and urban Saskatchewan; USK n=93). Physical activity was objectively assessed for seven consecutive days using Actigraph 7164 accelerometers. Custom software was used to reduce the raw accelerometer data into standardized outcome variables. Results: On weekdays there were group differences in moderate physical activity between all lifestyle groups (OOA > OOM > USK > RSK). On the weekend, the group differences in moderate physical activity persisted between, but not within, lifestyle groups (OOA = OOM > USK = RSK). During school hours, all groups had similar activity and sedentary timings; however, they differed in magnitude with the OOA and OOM being both more sedentary and more active. Compared to in school, the OOA and OOM children had 44% lower sedentary time out of school compared to only 15% lower for RSK and USK children. Conclusions: Though cross-sectional, these data suggest that contemporary/modern living is associated with lower levels of moderate and vigorous intensity physical activity compared to lifestyles representative of earlier generations. Analyzing the physical activity and sedentary patterns of traditional lifestyle groups such as the OOA and OOM can provide valuable insight into the quantity and quality of physical activity necessary to promote health. General Conclusions: Together, these three studies will help contribute to the generation of best practices in the accelerometric profiling of both physical activity and sedentary behaviours

Accelerometer assessment of physical activity in active, healthy older adults

Despite widespread use of accelerometers to objectively monitor physical activity among adults and youth, little attention has been given to older populations. The purpose of this study was to define an accelerometer-count cut point for a group of older adults and to then assess the group's physical activity for 7 days. Participants (N = 38, age 69.7 ± 3.5 yr) completed a laboratory-based calibration with an Actigraph 7164 accelerometer. The cut point defining moderate to vigorous physical activity (MVPA) was 1,041 counts/min. On average, participants obtained 68 min of MVPA per day, although more than 65% of this occurred as sporadic activity. Longer bouts of activity occurred in the morning (6 a.m. to 12 p.m.) more frequently than other times of the day. Almost 14 hr/day were spent in light-intensity activity. This study demonstrates the rich information that accelerometers provide about older adult activity patterns - information that might further our understanding of the relationship between physical activity and healthy aging

The mediation effect of political interest on the connection between social trust and wellbeing among older adults

Previous research has established significant positive associations between social trust and wellbeing among older adults. This study aimed to obtain a deeper understanding of the relationship between different sources of social trust and wellbeing by examining the mediational role of political interest. A sample of 4,406 Italian residents aged 65 years and over was extracted from a national cross-sectional survey during 2013 in Italy, representative of the non-institutionalised population. Measures included trust in people, trust in institutions, political interest, life satisfaction and self-perceived health. Mediation path analysis and structural equation modelling were used to test the mediation effects of political interest on the relationship between trust in people and trust in institutions with life satisfaction and self-perceived health. Associations between trust in people, life satisfaction and self-perceived health, and between trust in institutions and life satisfaction were partially mediated by political interest, while the association between trust in institutions and self-perceived health was fully mediated by political interest. Having high levels of political interest may thus enhance the relationship between social trust and wellbeing among older adults. These results suggest that interventions to enhance wellbeing in older adults may benefit from examining individuals’ levels of political interest

Lack of knowledge of physical activity guidelines: Can physical activity promotion campaigns do better?

Objectives: To identify the prevalence of knowledge of the current UK physical activity guidelines which were introduced in 2011 and prior physical activity guidelines (30 min on 5 days each week) within two large samples of UK adult's. To investigate whether knowledge of physical activity guidelines differs according to demographics such as ethnicity, age, education and employment status. Design: Descriptive cross-sectional study comparing two distinctive adult samples. Setting: National survey and online-administered survey conducted in England. Participants: The 2007 Health Survey for England provides data on knowledge of physical activity guidelines from 2860 UK adults (56% women, 89% white, 63% under 45 years old). In 2013, an online survey was disseminated and data were collected from 1797 UK adults on knowledge of the most recent physical activity guidelines. The 2013 sample was 70% women, 92% white and 57% under 45 years old. All adults in both samples were >18 years old and without illnesses/disorders likely to restrict physical activity. Main outcomes: Knowledge of physical activity guidelines in 2007 and 2013. Demographic correlates of knowledge of moderate-to-vigorous physical activity guidelines. Results: 18% of the 2013 sample accurately recalled the current physical activity guidelines compared with 11% of the 2007 sample who accurately recalled the previous guidelines. The differences in knowledge of physical activity guidelines existed for marital status, gender, age, education and employment status within both 2007 and 2013 samples (p<0.05). Men with lower education and employment status (unemployed including student and retired) and older adults were less likely to know physical activity guidelines (p<0.05). Knowledge of physical activity guidelines remained higher in the 2013 sample after controlling for demographic differences ( p<0.05). Conclusions: Disadvantaged population groups are less knowledgeable about physical activity guidelines. Although knowledge of physical activity guidelines appears to have increased in recent years demographic disparities are still evident. Efforts are needed to promote health information among these groups

A digital lifestyle behaviour change intervention for the prevention of type 2 diabetes:A qualitative study exploring intuitive engagement with real-time glucose and physical activity feedback

BACKGROUND: Mobile health technologies have advanced to now allow monitoring of the acute physiological responses to lifestyle behaviours. Our aim was to explore how people engaged with real-time feedback on their physical activity and glucose levels over several weeks. METHODS: Semi-structured interviews with 26 participants (61.5% female, 56.6 years) at moderate-to-high risk of developing type 2 diabetes were conducted. Interviews were completed after participants took part in an intervention comprising a flash glucose monitor (Freestyle Libre) and a physical activity monitor (Fitbit Charge 2). Purposive sampling ensured representation of ages, genders and group allocations. RESULTS: Inductive thematic analysis revealed how individuals intuitively used, interpreted and acted on feedback from wearable technologies. Six key themes emerged: triggers of engagement with the technologies, links between behaviour and health, lack of confidence, changes to movement behaviours, changes to diet and barriers to lifestyle behaviour change. CONCLUSIONS: Our findings demonstrate that accessing behavioural and physiological feedback can increase self-awareness of how lifestyle impacts short-term health. Some participants noticed a link between the feedback presented by the two devices and changed their behaviour but many did not. Training and educational support, as well as efforts to optimize how feedback is presented to users, are needed to sustain engagement and behaviour change. Extensions of this work to involve people with diabetes are also warranted to explore whether behavioural and physiological feedback in parallel can encourage better diabetes self-management. TRIAL REGISTRATION: ISRCTN Registry, ISRCTN17545949 , 12/05/2017, prospectively registered

Protocol for a feasibility trial to inform the development of a breathlessness rehabilitation programme for chronic obstructive pulmonary disease and chronic heart failure (the COHERE trial)

© 2019 Author(s). Introduction Adults with chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) commonly suffer from exertional dyspnoea and fatigue. Exercise training is recommended in the management of both diseases, yet many of the outcome measures traditionally reported are disease specific and may not fully acknowledge the multimorbid older adult. Based on our previous research, a breathlessness rehabilitation programme for patients with COPD/CHF or combined disease has been introduced as a service improvement within University Hospital Leicester National Health Service Trust and has amalgamated aspects of cardiac and pulmonary rehabilitation. This has created an opportunity to expand the outcome measures assessed and introduce a holistic approach in a population that share common symptoms. Therefore, this multisite trial will explore the feasibility of collecting novel outcome markers as part of a comprehensive assessment prior to enrolment in a breathlessness rehabilitation programme for participants with COPD and/or CHF. Methods and analysis The rehabilitation programme consists of 12 sessions, twice weekly, over a 6-week period. In addition to usual rehabilitation outcome measures, the trial will collect measures of future cardiometabolic risk including arterial stiffness, body composition, physical activity/sedentary time, frailty and symptom burden in a comprehensive rehabilitation assessment. The primary outcome measures will centre around feasibility (eg, acceptability of the comprehensive rehabilitation assessment, intervention delivery and the experiences and attitudes of healthcare professionals and participants). Focus groups and interviews will be conducted to further explore barriers and facilitators to the operation and participation in a breathlessness rehabilitation programme and the trial. Thematic analysis will be used for the interpretation of all qualitative data. Ethics and dissemination The research ethics committee East Midlands Leicester-Central has provided ethical approval for the conduct of this trial. The results of the trial will be disseminated through appropriate conference proceedings and peer-reviewed journals. Trial registration number ISRCTN1163630

Technologies that assess the location of physical activity and sedentary behavior: a systematic review

Background: The location in which physical activity and sedentary behavior are performed can provide valuable behavioral information, both in isolation and synergistically with other areas of physical activity and sedentary behavior research. Global positioning systems (GPS) have been used in physical activity research to identify outdoor location; however, while GPS can receive signals in certain indoor environments, it is not able to provide room- or subroom-level location. On average, adults spend a high proportion of their time indoors. A measure of indoor location would, therefore, provide valuable behavioral information. Objective: This systematic review sought to identify and critique technology which has been or could be used to assess the location of physical activity and sedentary behavior. Methods: To identify published research papers, four electronic databases were searched using key terms built around behavior, technology, and location. To be eligible for inclusion, papers were required to be published in English and describe a wearable or portable technology or device capable of measuring location. Searches were performed up to February 4, 2015. This was supplemented by backward and forward reference searching. In an attempt to include novel devices which may not yet have made their way into the published research, searches were also performed using three Internet search engines. Specialized software was used to download search results and thus mitigate the potential pitfalls of changing search algorithms. Results: A total of 188 research papers met the inclusion criteria. Global positioning systems were the most widely used location technology in the published research, followed by wearable cameras, and radio-frequency identification. Internet search engines identified 81 global positioning systems, 35 real-time locating systems, and 21 wearable cameras. Real-time locating systems determine the indoor location of a wearable tag via the known location of reference nodes. Although the type of reference node and location determination method varies between manufacturers, Wi-Fi appears to be the most popular method. Conclusions: The addition of location information to existing measures of physical activity and sedentary behavior will provide important behavioral information

Conductive microfluidic interconnects to enable scalable 3D manufacturing of wearable electronics

This paper investigates the geometry and surface finish of channels machined into polydimethylsiloxane using a continuous wave CO2 laser. In order to investigate the various mechanisms, that could affect the channel geometry, both the laser power and trace speed were varied in conjunction with the use of a fixed focal size to allow comparison between configurations. It was discovered that as the power level increases, repeatability decreases while dimensional variability of the channel along its length and multiple iterations increases. It was found that the power output of the laser has a greater effect on the dimensions of the channels than the total energy input into the material. Varying configurations were used when creating these channels resulting in a strong correlation between both power and speed with regard to depth. However, at higher energy levels this relationship appears to break down and the depth of the cut reduces when compared to similar laser configurations at a lower power level

Novel technology to help understand the context of physical activity and sedentary behaviour.

When used in large, national surveillance programmes, objective measurement tools provide prevalence estimates of low physical activity guideline compliance and high amounts of sedentary time. There are undoubtedly a plethora of reasons for this but one possible contributing factor is the current lack of behavioural context offered by accelerometers and posture sensors. Context includes information such as where the behaviour occurs, the type of activity being performed and is vital in allowing greater refinement of intervention strategies. Novel technologies are emerging with the potential to provide this information. Example data from three ongoing studies is used to illustrate the utility of these technologies. Study one assesses the concurrent validity of electrical energy monitoring and wearable cameras as measures of television viewing. This study found that on average the television is switched on for 202 min d(-1) but is visible in just 90 min of wearable camera images with a further 52 min where the participant is in their living room but the television is not visible in the image. Study two utilises indoor location monitoring to assess where older adult care home residents accumulate their sedentary time. This study found that residents were highly sedentary (sitting for an average of 720 min d(-1)) and spent the majority of their time in their own rooms with more time spent in communal areas in the morning than in the afternoon. Lastly, study three discusses the use of proximity sensors to quantify exposure to a height adjustable desk. These studies are example applications of this technology, with many other technologies available and applications possible. The adoption of these technologies will provide researchers with a more complete understanding of the behaviour than has previously been available

Can functional magnetic resonance imaging studies help with the optimization of health messaging for lifestyle behavior change? A systematic review

Unhealthy behaviours, including smoking, poor nutrition, excessive alcohol consumption, physical inactivity and sedentary lifestyles, are global risk factors for non-communicable diseases and premature death. Functional magnetic resonance imaging (fMRI) offers a unique approach to optimize health messages by examining how the brain responds to information relating to health. Our aim was to systematically review fMRI studies that have investigated variations in brain activation in response to health messages relating to (i) smoking; (ii) alcohol consumption; (iii) physical activity; (iv) diet; and (v) sedentary behaviour. The electronic databases used were Medline/PubMed, Web of Science (Core Collection), PsychINFO, SPORTDiscuss, Cochrane Library and Open Grey. Studies were included if they investigated subjects aged ≥10 years and were published before January 2017. Of the 13,836 studies identified in the database search, 18 studies (smoking k=15; diet k=2; physical activity/sedentary behavior k=1) were included in the review. The prefrontal cortex was activated in seven (47%) of the smoking-related studies and the physical activity study. Results suggest that activation of the ventromedial, dorsolateral and medial prefrontal cortex regions were predictive of subsequent behavior change following exposure to aversive anti-smoking stimuli. Studies investigating the neurological responses to anti-smoking material were most abundant. Of note, the prefrontal cortex and amygdala were most commonly activated in response to health messages across lifestyle behaviors. The review highlights an important disparity between research focusing on different lifestyle behaviors. Insights from smoking literature suggests fMRI may help to optimize health messaging in relation to other lifestyle behaviors