Development and performance of a sleep estimation algorithm using a single accelerometer placed on the thigh: an evaluation against polysomnography.

Accelerometers placed on the thigh provide accurate measures of daily physical activity types, postures and sedentary behaviours, over 24 h and across consecutive days. However, the ability to estimate sleep duration or quality from thigh-worn accelerometers is uncertain and has not been evaluated in comparison with the 'gold-standard' measurement of sleep polysomnography. This study aimed to develop an algorithm for sleep estimation using the raw data from a thigh-worn accelerometer and to evaluate it in comparison with polysomnography. The algorithm was developed and optimised on a dataset consisting of 23 single-night polysomnography recordings, collected in a laboratory, from 15 asymptomatic adults. This optimised algorithm was then applied to a separate evaluation dataset, in which, 71 adult males (mean [SD] age 57 [11] years, height 181 [6] cm, weight 82 [13] kg) wore ambulatory polysomnography equipment and a thigh-worn accelerometer, simultaneously, whilst sleeping at home. Compared with polysomnography, the algorithm had a sensitivity of 0.84 and a specificity of 0.55 when estimating sleep periods. Sleep intervals were underestimated by 21 min (130 min, Limits of Agreement Range [LoAR]). Total sleep time was underestimated by 32 min (233 min LoAR). Our results evaluate the performance of a new algorithm for estimating sleep and outline the limitations. Based on these results, we conclude that a single device can provide estimates of the sleep interval and total sleep time with sufficient accuracy for the measurement of daily physical activity, sedentary behaviour, and sleep, on a group level in free-living settings.

Resilient Control for Macroeconomic Models.

This paper derives a macroeconomic resilient control framework that provides the optimal feedback fiscal and monetary policy responses in response to a potentially large negative external incident. We simulate the model for the U.S. under the conditions that prevailed throughout the 2020 economic crisis that occurred due to the government lockdown that was caused by the coronavirus pandemic. We develop a discrete-time soft-constrained linear-quadratic dynamic game under a worst-case design with multiple disturbances. Within this context, we introduce a resilience feedback response and compare the case where the policymakers counter in response the external incident with the case when they do not counter. This framework is especially applicable to large-scale macroeconomic tracking control models and wavelet-based control models when formulating the magnitudes of the policy changes necessary for the unemployment rate and national output variables to maintain acceptable tracking errors in the periods following a major disruption. Our policy recommendations include the maintenance of "rainy day" funds at appropriate levels of government to mitigate the effects of large adverse events.

Number of steps and systolic blood pressure: Do work and leisure matter?

The number of steps per day influences blood pressure and health. However, the association between steps at work and leisure and blood pressure is unknown. Thus, we aimed to investigate the association between the domain-specific number of steps and systolic blood pressure. A thigh-worn accelerometer was used to measure the steps of 694 workers over 1-5 consecutive days, separated into work and leisure domains using a self-reported diary. We linearly regressed steps at work, leisure and total day against systolic blood pressure, adjusting for age, sex, body mass index, smoking, and antihypertensive medication. Additionally, we stratified the analyses on job type (blue-collar or white-collar). The results of this cross-sectional analysis indicated a beneficial association between the number of steps (per 2000-step interval) and systolic blood pressure for the total day (-0.5 mmHg; -1.0 to -0.8, 95% CI, p < 0.05) and work (-0.9 mmHg; -1.5 to -0.4, 95% CI, p < 0.05), but not for leisure (+0.1 mmHg; -0.7 to 0.9, 95% CI, p = 0.75). Blue-collar workers took almost twice as many steps at work (9143 ± SD3837) as white-collar workers (5863 ± SD3565) and, after stratification on job type, we observed a beneficial association between the number of steps at work and systolic blood pressure among blue-collar workers (-1.1 mmHg; -1.7 to -0.4, 95% CI, p < 0.05), but not for white-collar workers (-0.3 mmHg; -1.7 to 1.1, 95% CI, p = 0.7). These findings indicate that the number of steps at work, particularly among blue-collar workers, is beneficially associated with systolic blood pressure. Such findings support the potential of work (re)design to promote walking to improve blood pressure.

Cardiorespiratory fitness, occupational aerobic workload and age: workplace measurements among blue-collar workers.

BACKGROUND: The knowledge, from laboratory studies dating back to the 1950s on the importance of the association between cardiorespiratory fitness and aerobic workload for workers health, is fundamental for promoting sustainable healthy employability among ageing blue-collar workers today. However, the association between cardiorespiratory fitness and aerobic workload has not yet been documented during daily work, and we do not know if it applies to the normal work of blue-collar workers in different age groups. We aim to investigate the association between cardiorespiratory fitness and aerobic workload among blue-collar workers using measurements of 24-h heart rate collected over consecutive working days. METHODS: We analyzed baseline cardiorespiratory fitness, assessed using a sub-maximal cycle ergometer test, and 1-4 days of 24-h heart rate measurement from 497 blue-collar workers participating in the DPHACTO study. We investigated the association between cardiorespiratory fitness and aerobic workload defined as the average percentage of heart rate reserve (%HRR), maximum %HRR and the duration time spent at a high HRR (> 30%) during working hours. The association was assessed using multivariate linear regression models adjusted for age, sex, self-rated health, shift-work, prescription medication and occupation, as well as for different age strata. RESULTS: Higher cardiorespiratory fitness was significantly associated with decreased mean %HRR -0.32 [95% CI -0.39 to -0.25], maximum %HRR -0.35 [95% CI -0.45 to -0.25] and time spent at ≥ 30% HRR; -1.8% [95% CI -2.2 to -1.5%]. These associations were evident across age groups, with slightly stronger associations for workers aged 46-51 (total range 18-68). CONCLUSIONS: Higher cardiorespiratory fitness was associated with the decreased aerobic workload during normal work across all age groups and levels of work intensity. Our findings highlight the importance of cardiorespiratory fitness when considering the workload and its relevance in the promotion of healthy sustainable employment.

Frontline Nurse Feedback During the Development of a System to Track Cleaning of Portable Medical Equipment.

As part of the development and testing of an innovative technology for tracking disinfection of portable medical equipment, end-user feedback was obtained during an initial trial on two acute care hospital units. The disinfection tracking device was installed on the computers-on-wheels and vital signs machines. Each device had the capability of detecting a cleaning event, reporting the event to an online database, and displaying the time since last cleaning event on a visual display. End-user feedback regarding functionality, usefulness of information provided, and impact on workflow was obtained by survey and facilitated group discussions. Seventeen frontline nurses completed the anonymous survey, and 22 participated in the facilitated group discussions. End users found the system functionally easy to use and the information about time since last cleaning useful and reported minimum disruption of workflow. Functionality of the system was confirmed by consistency between recorded and self-reported cleaning patterns. Managers found the data on cleaning of portable medical equipment helpful in validating compliance with hospital equipment cleaning policy. Frontline staff expressed appreciation for technology that helps them and improves outcomes but also discussed concerns about the potential for technology that creates extra work and disruption in the busy frontline nursing care delivery environment. Nurses were appreciative of opportunities to provide feedback and input into efforts to develop and introduce technology. Recorded cleaning events coincided with self-reported equipment cleaning patterns and illustrated that the device efficiently collects information deemed useful by the end user.

Changes in body composition and substrate utilization after a short-term ketogenic diet in endurance-trained males.

Few studies have investigated the short-term effects of a very low carbohydrate ketogenic diet (KD) on body composition and substrate utilization in trained individuals. This study investigated effects on substrate utilization during incremental exercise, and changes in body composition, in response to seven days ad libitum consumption of a KD by athletes from endurance sports. Nine young trained males (age, 21.8 ± 1.9 y; height, 1.83 ± 0.11 m; body mass, 78.4 ± 13.8 kg; body fat, 14.9 ± 3.9%; VO2peak, 54.3 ± 5.9 mL kg-1 min-1) were assessed before (day 0; PRE) and after (day 7; POST) seven days of consuming an ad libitum KD. Following an overnight fast, body composition was measured by dual x-ray absorptiometry, and substrate utilization was measured during an incremental (3 min stages, 35 W increments) exercise test on a cycle ergometer. After KD, Wmax (PRE, 295 ± 30 W; POST, 292 ± 38 W) and VO2peak (PRE, 4.18 ± 0.33 L min-1; POST, 4.10 ± 0.43 L min-1) were unchanged, whereas body mass [-2.4 (-3.2, -1.6) kg; P < 0.001, d = 0.21], fat mass [-0.78 (-1.10, -0.46) kg; P < 0.001, d = 0.22] and fat-free mass (FFM) [-1.82 (-3.12, -0.51) kg; P = 0.013, d = 0.22] all decreased. The respiratory exchange ratio was lower, and rates of fat oxidation were higher, at POST across a range of exercise intensities. Maximal fat oxidation rate was ~1.8-fold higher after KD (PRE, 0.54 ± 0.13 g min-1; POST, 0.95 ± 0.24 g min-1; P < 0.001, d = 2.2). Short-term KD results in loss of both fat mass and FFM, increased rates of fat oxidation and a concomitant reduction in CHO utilization even at moderate-to-high intensities of exercise.

Zero problems with compositional data of physical behaviors: a comparison of three zero replacement methods.

BACKGROUND: Researchers applying compositional data analysis to time-use data (e.g., time spent in physical behaviors) often face the problem of zeros, that is, recordings of zero time spent in any of the studied behaviors. Zeros hinder the application of compositional data analysis because the analysis is based on log-ratios. One way to overcome this challenge is to replace the zeros with sensible small values. The aim of this study was to compare the performance of three existing replacement methods used within physical behavior time-use epidemiology: simple replacement, multiplicative replacement, and log-ratio expectation-maximization (lrEM) algorithm. Moreover, we assessed the consequence of choosing replacement values higher than the lowest observed value for a given behavior. METHOD: Using a complete dataset based on accelerometer data from 1310 Danish adults as reference, multiple datasets were simulated across six scenarios of zeros (5-30% zeros in 5% increments). Moreover, four examples were produced based on real data, in which, 10 and 20% zeros were imposed and replaced using a replacement value of 0.5 min, 65% of the observation threshold, or an estimated value below the observation threshold. For the simulation study and the examples, the zeros were replaced using the three replacement methods and the degree of distortion introduced was assessed by comparison with the complete dataset. RESULTS: The lrEM method outperformed the other replacement methods as it had the smallest influence on the structure of relative variation of the datasets. Both the simple and multiplicative replacements introduced higher distortion, particularly in scenarios with more than 10% zeros; although the latter, like the lrEM, does preserve the ratios between behaviors with no zeros. The examples revealed that replacing zeros with a value higher than the observation threshold severely affected the structure of relative variation. CONCLUSIONS: Given our findings, we encourage the use of replacement methods that preserve the relative structure of physical behavior data, as achieved by the multiplicative and lrEM replacements, and to avoid simple replacement. Moreover, we do not recommend replacing zeros with values higher than the lowest observed value for a behavior.

Light-intensity physical activity derived from count or activity types is differently associated with adiposity markers.

AIM: The aim of this study was to compare the association between count- and activity type-based definitions of light-intensity physical activity (LIPA) and adiposity markers. METHODS: A total of 516 Danish workers participated in 1-4 days of hip- and thigh-based accelerometer measurements. Three definitions of average daily time spent in LIPA were derived: LIPA (1) time spent between 100 and 2029 CPM, LIPA (2) time spent moving and slow walking, and LIPA (3) time spent moving, walking slow, and standing. Adiposity markers were body mass index (BMI), body fat percentage, and waist circumference. The cross-sectional association between the three LIPA definitions and adiposity markers was analyzed and interpreted using compositional regression models followed by reallocation of time between LIPA, moderate-to-vigorous physical activity (MVPA), and sedentary behavior (SB), respectively. RESULTS: The geometric means of daily time (min/day) spent in LIPA 1, LIPA 2, and LIPA 3 were 326, 102, and 274, respectively. We found the direction and strength of the association between the relative importance of daily time spent in LIPA and the adiposity markers to depend on the LIPA definition. For example, reallocating 30 minutes from MVPA to LIPA 1, LIPA 2 and LIPA 3 were associated with a 2.97 (95% CI: 0.68; 5.27), -0.71 (95% CI: -1.43; 0.02), and -0.45 (95% CI: -1.01; 0.11) difference in BMI, respectively. CONCLUSION: Our findings highlight the need for caution when comparing results from studies using different definitions of LIPA.

Comparison of physical behavior estimates from three different thigh-worn accelerometers brands: a proof-of-concept for the Prospective Physical Activity, Sitting, and Sleep consortium (ProPASS).

BACKGROUND: Pooling data from thigh-worn accelerometers across multiple studies has great potential to advance evidence on the health benefits of physical activity. This requires harmonization of information on body postures, physical activity types, volumes and time patterns across different brands of devices. The aim of this study is to compare the physical behavior estimates provided by three different brands of thigh-worn accelerometers. METHODS: Twenty participants volunteered for a 7-day free-living measurement. Three accelerometers - ActiGraph GT3X+, Axivity AX3 and ActivPAL Micro4 - were randomly placed in a vertical line on the midsection of the right thigh. Raw data from each accelerometer was processed and classified into 8 physical activities and postures using the Acti4 software. Absolute differences between estimates and the respective coefficient of variation (CV) were calculated. RESULTS: We observed very minor differences between physical behavior estimates from three different accelerometer brands. When averaged over 24 h (1,440 min), the absolute difference (CV) between accelerometers were: 1.2 mins (0.001) for lying/sitting, 3.4 mins (0.02) for standing, 3.5 mins (0.06) for moving, 1.9 mins (0.03) for walking, 0.1 mins (0.19) for running, 1.2 mins (0.19) for stair climbing, 1.9 mins (0.07) for cycling. Moreover, there was an average absolute difference of 282 steps (0.03) per 24 h. CONCLUSIONS: Physical behaviors were classified with negligible difference between the accelerometer brands. These results support harmonization of data from different thigh-worn accelerometers across multiple cohorts when analyzed in an identical manner.

Dramatic impact of using protective equipment on the level of hurling-related head injuries: an ultimately successful 27-year programme.

BACKGROUND: Major head injuries are not uncommon in the Irish national game of hurling. Historically, helmets were not worn. METHODS: We report a multistage campaign to facilitate and encourage the use of appropriate headgear among the estimated 100 000 hurling players in Ireland. This campaign lasted for 27 years between 1985 and 2012, and involved a number of different stages including: (1) facilitating the establishment of a business dedicated to developing head protection equipment suitable for hurling, (2) placing a particular emphasis on continual product enhancement to the highest industrial standards, (3) engaging continually with the game's controlling body, the Gaelic Athletic Association (GAA), with the ultimate objective of securing a mandatory usage policy for protective helmets and faceguards, (4) longitudinal research to monitor hurling injury, equipment usage and players' attitudes and (5) widely communicating key research findings to GAA leaders and members, as well as to 1000 clubs and schools. RESULTS: One of our three relevant studies included 798 patients and identified a dramatic association between the type of head protection used by a player, if any, and the site of the injury requiring treatment. While 51% of the injured players without head protection suffered head trauma, this rate was only 35% among the players wearing helmets and 5% among players who were wearing full head protection (both a helmet and faceguard). CONCLUSION: The GAA responded in three stages to the accumulating evidence: (1) they introduced a mandatory regulation for those aged less than 18 years in 2005; (2) this ruling was extended to all players under 21 years in 2007 and (3) finally extended to all players irrespective of age, gender or grade from January 2010. The latter ruling applied to both games and organised training sessions.

Antibiotics at End of Life: Where Are We Now and Where Are We Going? A Narrative Review.

BACKGROUND: Antibiotics are frequently prescribed at the end of life, though the benefits and harms are not well understood. METHODS: We abstracted relevant findings from articles published in English in the past 25 years to answer questions generated by discussion among the authors and with stakeholders in Palliative Care and Infectious Diseases. FINDINGS: Prescribing practices vary based on individual situation and geographic location. Patients with cancer and those hospitalized receive more antibiotics than those enrolled in outpatient hospice. Urinary tract infections and pulmonary infections are the most common conditions treated with antibiotics at the end of life -most often with penicillin derivatives and vancomycin in the hospital, fluoroquinolones in outpatient, and cephalosporins in both settings. When asked, patients most often prefer limiting antibiotics to symptom management at the end of life. Physicians' over-estimation of patient preference for antibiotics and the increased probability of misdiagnosis increases antibiotic prescription rates. Antibiotics can improve symptoms when used for specific diseases at the cost of drug reactions, resistant organisms, and delayed discharge. Antibiotic use has variable results on survival duration. Antimicrobial stewardship exists in hospital and long-term care facilities, but not outpatient hospice groups. Stewardship interventions could increase proper use of antibiotics, but more information is needed to apply these interventions to hospice groups. CONCLUSIONS: Antibiotics at the end of life are impactful and efforts to educate patients and providers will be invaluable in optimizing care.

Development and deployment of a histopathology-based deep learning algorithm for patient prescreening in a clinical trial.

Accurate identification of genetic alterations in tumors, such as Fibroblast Growth Factor Receptor, is crucial for treating with targeted therapies; however, molecular testing can delay patient care due to the time and tissue required. Successful development, validation, and deployment of an AI-based, biomarker-detection algorithm could reduce screening cost and accelerate patient recruitment. Here, we develop a deep-learning algorithm using >3000 H&E-stained whole slide images from patients with advanced urothelial cancers, optimized for high sensitivity to avoid ruling out trial-eligible patients. The algorithm is validated on a dataset of 350 patients, achieving an area under the curve of 0.75, specificity of 31.8% at 88.7% sensitivity, and projected 28.7% reduction in molecular testing. We successfully deploy the system in a non-interventional study comprising 89 global study clinical sites and demonstrate its potential to prioritize/deprioritize molecular testing resources and provide substantial cost savings in the drug development and clinical settings.

A Novel System for the Device-Based Measurement of Physical Activity, Sedentary Behavior, and Sleep (Motus): Usability Evaluation.

BACKGROUND: Device-based measurements of physical behavior, using the current methods, place a large burden on participants. The Motus system could reduce this burden by removing the necessity for in-person meetings, replacing diaries written on paper with digital diaries, and increasing the automation of feedback generation. OBJECTIVE: This study aims to describe the development of the Motus system and evaluate its potential to reduce participant burden in a two-phase usability evaluation. METHODS: Motus was developed around (1) a thigh-worn accelerometer with Bluetooth data transfer; (2) a smartphone app containing an attachment guide, a digital diary, and facilitating automated data transfer; (3) a cloud infrastructure for data storage; (4) an analysis software to generate feedback for participants; and (5) a web-based app for administrators. We recruited 19 adults with a mean age of 45 (SD 11; range 27-63) years, of which 11 were female, to assist in the two-phase evaluation of Motus. A total of 7 participants evaluated the usability of mockups for a smartphone app in phase 1. Participants interacted with the app while thinking aloud, and any issues raised were classified as critical, serious, or minor by observers. This information was used to create an improved and functional smartphone app for evaluation in phase 2. A total of 12 participants completed a 7-day free-living measurement with Motus in phase 2. On day 1, participants attempted 20 system-related tasks under observation, including registration on the study web page, reading the information letter, downloading and navigating the smartphone app, attaching an accelerometer on the thigh, and completing a diary entry for both work and sleep hours. Task completion success and any issues encountered were noted by the observer. On completion of the 7-day measurement, participants provided a rating from 0 to 100 on the System Usability Scale and participated in a semistructured interview aimed at understanding their experience in more detail. RESULTS: The task completion rate for the 20 tasks was 100% for 13 tasks, >80% for 4 tasks, and <50% for 3 tasks. The average rating of system usability was 86 on a 0-100 scale. Thematic analysis indicated that participants perceived the system as easy to use and remember, and subjectively pleasing overall. Participants with shift work reported difficulty with entering sleep hours, and 66% (8/12) of the participants experienced slow data transfer between the app and the cloud infrastructure. Finally, a few participants desired a greater degree of detail in the generated feedback. CONCLUSIONS: Our two-phase usability evaluation indicated that the overall usability of the Motus system is high in free-living. Issues around the system's slow data transfer, participants with atypical work shifts, and the degree of automation and detail of generated feedback should be addressed in future iterations of the Motus system. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/35697.

Effect of a "feedback prompt" from a disinfection tracking system on portable medical equipment disinfection.

BACKGROUND: Portable medical equipment (PME) may contribute to transmission of multidrug-resistant organisms without proper disinfection. We studied whether a Disinfection Tracking System (DTS) with feedback prompt, attached to PME, can increase the frequency of PME disinfection. METHODS: DTS devices were placed on 10 workstations-on-wheels (WOWs) and 5 vitals machine (VM). After a 25 day "screen-off" period, the DTS device screens were turned on to display the number of hours since the last recorded disinfection event for a 42 day period. We used a Bayesian multilevel zero-inflated negative binomial model to compare the number of events in the display "screen-off" to the "screen-on" period. RESULTS: During the "screen-off" period, there were 1.26 and 0.49 mean disinfection events and during the "screen-on" period, there were 1.76 and 0.50 mean disinfection events for WOWs and VM, respectively, per day. The model estimated mean events per device per day in the the "screen-on" period for WOW's were 1.32 (1.10 - 1.57) times greater than those in the "screen-off" period and the "screen-on" period for VM devices was 1.37 (0.89 - 2.01) times greater than those in the "screen-off" period. CONCLUSIONS: The rate of disinfection events for WOWs increased following the implementation of the DTS feedback prompt.

The Surveillance of Physical Activity, Sedentary Behavior, and Sleep: Protocol for the Development and Feasibility Evaluation of a Novel Measurement System.

BACKGROUND: There is increasing recognition of the need for more comprehensive surveillance data, including information on physical activity of all intensities, sedentary behavior, and sleep. However, meeting this need poses significant challenges for current surveillance systems, which are mainly reliant on self-report. OBJECTIVE: The primary objective of this project is to develop and evaluate the feasibility of a sensor-based system for use in the surveillance of physical activity, sedentary behavior, and sleep (SurPASS) at a national level in Denmark. METHODS: The SurPASS project involves an international, multidisciplinary team of researchers collaborating with an industrial partner. The SurPASS system consists of (1) a thigh-worn accelerometer with Bluetooth connectivity, (2) a smartphone app, (3) an integrated back end, facilitating the automated upload, analysis, storage, and provision of individualized feedback in a manner compliant with European Union regulations on data privacy, and (4) an administrator web interface (web application) to monitor progress. The system development and evaluation will be performed in 3 phases. These phases will include gathering user input and specifications (phase 1), the iterative development, evaluation, and refinement of the system (phase 2), and the feasibility evaluation (phase 3). RESULTS: The project started in September 2020 and completed phase 2 in February 2022. Phase 3 began in March 2022 and results will be made available in 2023. CONCLUSIONS: If feasible, the SurPASS system could be a catalyst toward large-scale, sensor-based surveillance of physical activity, sedentary behavior, and sleep. It could also be adapted for cohort and interventional research, thus contributing to the generation of evidence for both interventions and public health policies and recommendations. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35697.

The effects of walking speed and mobile phone use on the walking dynamics of young adults.

Walking while using a mobile phone has been shown to affect the walking dynamics of young adults. However, this has only been investigated using treadmill walking at a fixed walking speed. In this study, the dynamics of over ground walking were investigated using lower trunk acceleration measured over 12 consecutive trials, following differing walking speed and mobile phone use instructions. Higher walking speed significantly increased the proportion of acceleration along the vertical measurement axis, while decreasing the proportion of acceleration along the anteroposterior axis (p < 0.001). Moreover, higher walking speed also resulted in increased sample entropy along all measurement axes (p < 0.05). When walking while texting, the maximum Lyapunov exponent increased along the anteroposterior and vertical measurement axes (p < 0.05), while sample entropy decreased significantly along the vertical axis (p < 0.001). Walking speed and mobile phone use both affect the walking dynamics of young adults. Walking while texting appears to produce a reduction in local dynamic stability and an increase in regularity, however, caution is required when interpreting the extent of this task effect, since walking speed also affected walking dynamics.

Accelerometer-Measured Physical Activity at Work and Need for Recovery: A Compositional Analysis of Cross-sectional Data.

OBJECTIVES: Previous research has shown strong associations between occupational physical activity (OPA) and need for recovery (NFR). However this research has only utilized self-reported measures of OPA which may be biased. Thus, there is a need for investigating if the previously documented association between self-reported OPA and NFR can be found when using technical measures of OPA. There is also the need to investigate whether older workers are particularly susceptible to increased NFR, since age-related declines in physical capacity mean that it is likely these workers will have a higher NFR for a given physical activity. The aim of this study was to investigate the association between technically measured OPA and NFR, and whether this relationship is modified by age. METHODS: This study utilized data from the Danish Physical Activity Cohort with Objective Measurements cohort-comprising Danish workers (n = 840) from the cleaning, manufacturing, and transportation sectors. OPA was measured by accelerometers attached to the thigh and upper back for at least one work day and classified into four physical behaviour categories (sedentary, standing, light, or moderate/vigorous). NFR was measured using a shortened version of the Danish NFR scale. Analysis was conducted using linear regression and isotemporal substitution analyses for compositional data. RESULTS: The overall association between OPA and NFR was statistically significant in the unadjusted model (P < 0.001), but not when adjusted for age, sex, occupation, and shift work (P = 0.166). Isotemporal substitution showed small but significant reductions in NFR when increasing sedentary time relative to other behaviours (adjusted: ΔNFR = -0.010 [-0.019; -0.001]). There were no significant interactions between age and OPA (P = 0.409). CONCLUSIONS: This study found significant associations between OPA and NFR, but the effect sizes were small. Reallocating 30 min to sedentary behaviours from other behaviours was associated with a reduced NFR, but the effect size may not be practically relevant. Moreover, no clear modifying effects of age were identified.

Thigh-worn accelerometry for measuring movement and posture across the 24-hour cycle: a scoping review and expert statement.

INTRODUCTION: The Prospective Physical Activity Sitting and Sleep consortium (ProPASS) is an international collaboration platform committed to harmonise thigh-worn accelerometry data. The aim of this paper is to (1) outline observational thigh-worn accelerometry studies and (2) summarise key strategic directions arising from the inaugural ProPASS meeting. METHODS: (1) We performed a systematic scoping review for observational studies of thigh-worn triaxial accelerometers in free-living adults (n≥100, 24 hours monitoring protocols). (2)Attendees of the inaugural ProPASS meeting were sent a survey focused on areas related to developing ProPASS: important terminology (Q1); accelerometry constructs (Q2); advantages and distinct contribution of the consortium (Q3); data pooling and harmonisation (Q4); data access and sharing (Q5 and Q6). RESULTS: (1) Eighty eligible articles were identified (22 primary studies; n~17 685). The accelerometers used most often were the ActivPAL3 and ActiGraph GT3X. The most commonly collected health outcomes were cardiometabolic and musculoskeletal. (2) None of the survey questions elicited the predefined 60% agreement. Survey responses recommended that ProPASS: use the term physical behaviour or movement behaviour rather than 'physical activity' for the data we are collecting (Q1); make only minor changes to ProPASS's accelerometry construct (Q2); prioritise developing standardised protocols/tools (Q4); facilitate flexible methods of data sharing and access (Q5 and Q6). CONCLUSIONS: Thigh-worn accelerometry is an emerging method of capturing movement and posture across the 24 hours cycle. In 2020, the literature is limited to 22 primary studies from high-income western countries. This work identified ProPASS's strategic directions-indicating areas where ProPASS can most benefit the field of research: use of clear terminology, refinement of the measured construct, standardised protocols/tools and flexible data sharing.