Validity of the Acti4 method for detection of physical activity types in free-living settings: comparison with video analysis

Objectively measured occupational physical activity in blue-collar workers: What is the role of job type, gender and psychosocial resources?

The aim was to describe occupational physical activity (OPA) and examine the role of psychosocial job resources among blue-collar workers. In a sample of 198 workers (57% male; mean age 44.9 (SD 9.9) year) from 7 companies in Denmark, two accelerometers (Actigraph) were placed on the thigh and trunk during 1-5 consecutive days, to determine working time spent standing, walking, on feet and in activity of moderate to vigorous intensity level (MVPA). The level of influence and social support at work were assessed by questionnaire. The exposure to OPA significantly varied by particular job type, especially in male predominant occupations. Overall, psychosocial job resources did not affect the exposure to OPA. These findings suggest that workplace interventions aiming to prevent adverse outcomes of OPA among blue-collars workers ought to focus on task redesign and target work organizational factors related to specific job type.

Objectively measured versus self-reported occupational physical activity and multisite musculoskeletal pain: a prospective follow-up study at 20 nursing homes in Denmark

Purpose

To explore the prospective association of objectively measured and self-reported occupational physical activity (OPA) with multisite musculoskeletal pain (MSP) among Danish eldercare workers.

Methods

The study population consisted of eldercare workers in 20 Danish nursing homes (N = 553, response rate 59%, 525 female). Baseline data were collected in 2013–2014 and the 1-year follow-up was completed in 2016. At baseline, we measured objective OPA by a thigh-worn ActiGraph GT3X + accelerometer during work and self-reported OPA by a questionnaire survey. Information on musculoskeletal pain during the past four weeks in seven different body sites was reported by a structured questionnaire at baseline (n = 389) and by SMS and telephone interview during follow-up (n = 284). MSP was defined as having pain in two or more body sites. Using log-binomial models we calculated risk ratios (RRs) with their 95% confidence intervals (CIs) to estimate the association between objectively measured and self-reported OPA and MSP.

Results

We found statistically significant positive associations between self-reported OPA (RR for high OPA 1.24, 95% CI 1.05–1.46) and MSP while there was no significant association found between objective OPA and MSP.

Conclusion

Our study indicates that self-reported, but not objectively measured OPA is positively associated with MSP. This finding highlights the need for better understanding, use, and interpretation of self-reported and objectively measured OPA in the study of MSP.

Time spent cycling, walking, running, standing and sedentary: a cross-sectional analysis of accelerometer-data from 1670 adults in the Copenhagen City Heart Study : Physical behaviours among 1670 Copenhageners

Background

Information about how much time adults spend cycling, walking and running can be used for planning and evaluating initiatives for active, healthy societies. The objectives of this study were to describe how much time adult Copenhageners cycle, walk, run, stand and spend sedentary using accelerometers, and to describe differences between population groups.

Methods

In the fifth examination of the Copenhagen City Heart Study, 2335 individuals gave consent to wear accelerometers (skin-attached; right thigh and iliac crest; 24 h/day, 7 consecutive days) of which 1670 fulfilled our inclusion criteria (≥16 h/day for ≥5 days; median wear time: 23.8 h/day). Daily time spent cycling, walking, running, standing and sedentary was derived from accelerometer-based data using the Acti4 software, and differences between sex, age groups, level of education and BMI were investigated using Kruskal-Wallis rank sum tests.

Results

Among those cycling (61%), the median cycling time was 8.3 min/day. The median time walking, running, standing and sedentary was 82.6, 0.1, 182.5 and 579.1 min/day, respectively. About 88% walked fast (i.e., ≥100 steps/min) ≥30 min/day. The shortest duration and lowest prevalence of cycling, walking and running were found among older individuals, those with a low level of education, and individuals being overweight or obese.

Conclusions

We found a long duration and high prevalence of cycling and walking, but also that many adult Copenhageners spent much time sedentary. Population groups with low participation in physical activities such as cycling and walking should be targeted in future initiatives towards an active, healthy society.

Calibration of Self-Reported Time Spent Sitting, Standing and Walking among Office Workers: A Compositional Data Analysis

We developed and evaluated calibration models predicting objectively measured sitting, standing and walking time from self-reported data using a compositional data analysis (CoDA) approach. A total of 98 office workers (48 women) at the Swedish Transport Administration participated. At baseline and three-months follow-up, time spent sitting, standing and walking at work was assessed for five working days using a thigh-worn accelerometer (Actigraph), as well as by self-report (IPAQ). Individual compositions of time spent in the three behaviors were expressed by isometric log-ratios (ILR). Calibration models predicting objectively measured ILRs from self-reported ILRs were constructed using baseline data, and then validated using follow-up data. Un-calibrated self-reports were inaccurate; root-mean-square (RMS) errors of ILRs for sitting, standing and walking were 1.21, 1.24 and 1.03, respectively. Calibration reduced these errors to 36% (sitting), 40% (standing), and 24% (walking) of those prior to calibration. Calibration models remained effective for follow-up data, reducing RMS errors to 33% (sitting), 51% (standing), and 31% (walking). Thus, compositional calibration models were effective in reducing errors in self-reported physical behaviors during office work. Calibration of self-reports may present a cost-effective method for obtaining physical behavior data with satisfying accuracy in large-scale cohort and intervention studies.

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.

Electronic supplementary material

The online version of this article (10.1186/s12966-019-0835-0) contains supplementary material, which is available to authorized users.

Movement behavior profiles and obesity: a latent profile analysis of 24-h time-use composition among Danish workers

BACKGROUND/OBJECTIVES

An element of obesity prevention is increasing total physical activity energy expenditure. However, this approach does not incorporate the balance of various movement behaviors-physical activity, sedentary behaviors and sleep-across domains of the day. We aimed to identify time-use profiles over work and leisure, termed 'movement behavior profiles' and to investigate their association with obesity.

SUBJECTS/METHODS

Eight-hundred-and-seven workers completed (a) thigh accelerometry and diaries to determine their 24-h composition of behaviors (sedentary and standing, light physical activity and moderate-to-vigorous physical activity at work and leisure, and time in bed) and (b) obesity measurements. Movement behavior profiles were determined using latent profile analyses of isometric log-ratios of the 24-h composition, and labeled according to animal movement behavior traits. Linear models were applied to determine the association between profiles and obesity.

RESULTS

Four profiles were identified, labeled as "Chimpanzees" (n = 226), "Lions" (n = 179), "Ants" (n = 244), and "Koalas" (n = 158). "Chimpanzees" work time was evenly distributed between behaviors while their leisure time was predominantly active. Compared to Chimpanzees, "Lions" were more active at work and sedentary during leisure and spent more time in bed; "Ants" were more active at work and during leisure; "Koalas" were more sedentary at work and leisure and spent similar time in bed. With "Chimpanzees" as reference, "Lions" had least favorable obesity indicators: +2.0 (95% confidence interval [CI] 0.6, 3.4) %body fat, +4.3 cm (1.4, 7.3) waist circumference and +1.0 (2.0, 0.0) Body Mass Index (BMI), followed by "Koalas" +2.0 (0.4, 3.7) %body fat, +3.1 cm (0.1, 6.0) waist circumference, and +0.8 (-0.30, 1.94) BMI. No significant differences were found between "Chimpanzees" and "Ants".

CONCLUSIONS

Movement behavior profiles across work and leisure time-use compositions are associated with obesity. Achieving adequate balance between work and leisure movement behaviors should be further investigated as a potential obesity prevention strategy.

Exposure to Upper Arm Elevation During Work Compared to Leisure Among 12 Different Occupations Measured with Triaxial Accelerometers

Regarding prevention of neck and shoulder pain (NSP), unsupported arm elevation is one factor that should be taken into account when performing work risk assessment. Triaxial accelerometers can be used to measure arm elevation over several days but it is not possible to differentiate between supported and unsupported arm elevation from accelerometers only. Supported arm elevation is more likely to exist during sitting than standing. The aim of the study was to evaluate the use of whole workday measurements of arm elevation with accelerometers to assess potentially harmful work exposure of arm elevation, by comparing arm elevation at work with arm elevation during leisure, in a population with diverse work tasks, and to assess how the exposure parameters were modified when upper arm elevation during sitting time was excluded. The participants, 197 workers belonging to 12 occupational groups with diverse work tasks, wore triaxial accelerometers on the dominant arm, hip, and back for 1–4 days to measure arm elevation and periods of sitting. None of the groups were found to have higher exposure to arm elevation during work compared to leisure. Even though some occupations where known to have work tasks that forced them to work with elevated arms to a large extent. A high proportion of arm elevation derived from sitting time, especially so during leisure. When arm elevation during sitting time was excluded from the analysis, arm elevation was significantly higher at work than during leisure among construction workers, garbage collectors, manufacturing workers, and domestic cleaners. Together this illustrates that it is not suitable to use whole workday measurments of arm elevation with accelerometer as a sole information source when assessing the risk for NSP due to arm elevation. Information on body posture can provide relevant contextual information in exposure assessments when it is known that the potential harmful exposure is performed in standing or walking.

Assessing physiological response mechanisms and the role of psychosocial job resources in the physical activity health paradox: study protocol for the Flemish Employees' Physical Activity (FEPA) study

Background

In the current labour system many workers are still exposed to heavy physical demands during their job. In contrast to leisure time physical activity (LTPA), occupational physical activity (OPA) is associated with an increased risk of cardiovascular diseases and all-cause mortality, termed “the physical activity (PA) health paradox”. In order to gain more insight into the PA health paradox, an exploration of structural preventive measures at the workplace is needed and therefore objective field measurements are highly recommended. The objective of this paper is to provide an overview of the protocol of the Flemish Employees’ Physical Activity (FEPA) study, including objective measurements of PA, heart rate (HR) and cardiorespiratory fitness (CRF) to gain more insight into the PA health paradox.

Methods

A total of 401 workers participated in the FEPA study across seven companies in the service and production sector in Belgium. The participants comprised 167 men and 234 women, aged 20 to 65 years. OPA and LTPA were assessed by two Axivity AX3 accelerometers on the thigh and upper back. Ambulatory HR was measured by the Faros eMotion 90° monitor. Both devices were worn during two to four consecutive working days. In addition, CRF was estimated by using the Harvard Step Test. Statistical analyses will be performed using Pearson correlation, and multiple regression adjusted for possible confounders.

Discussion

This study aims to provide a better insight in the PA health paradox and the possible buffering factors by using valid and objective measurements of PA and HR (both during LTPA and OPA) over multiple working days. The results of the study can contribute to the prevention of cardiovascular disease by providing tailored recommendations for participants with high levels of OPA and by disseminating the results and recommendations to workplaces, policy makers and occupational health practitioners.

Is high aerobic workload at work associated with leisure time physical activity and sedentary behaviour among blue-collar workers? A compositional data analysis based on accelerometer data

Objective

This study aimed to investigate the hypothesized negative association between duration of work time spent at a high relative aerobic workload and leisure time movement behaviours among blue-collar workers.

Methods

This was a cross-sectional study based on heart rate and accelerometer data from 803 blue-collar workers (447 men and 356 women). Relative aerobic workload was measured as percentage of heart rate reserve during work (%HRR). Leisure time movement behaviours were expressed in terms of leisure time spent in sedentary and active behaviours in uninterrupted bouts (i.e. <10 min, ≥10–30 min and >30 min). Compositional regression and isotemporal substitution models were used to assess the association between the predominance of work time spent at ≥40%HRR and leisure time spent in sedentary and active bouts. All analyses were stratified by sex.

Results

For men, there was no statistically significant association between the predominance of work time spent at ≥40%HRR and leisure time movement behaviours. Among women, the predominance of ≥40%HRR at work was negatively associated with relative leisure time spent in ≥10 min bouts of active behaviour (β^ = -0.21, p = 0.02) and a theoretical 15 min reallocation of work time from <40%HRR to ≥40%HRR was estimated to decrease active behaviour by 6 min during leisure time.

Conclusion

Our result highlights the need for considering work-related barriers for an active leisure time in high-risk populations. Longitudinal studies are warranted to disentangle the relationship between physically demanding work characteristics and leisure time movement behaviours in such populations.

Consistency of Sedentary Behavior Patterns among Office Workers with Long-Term Access to Sit-Stand Workstations

INTRODUCTION

Sit-stand workstations are a popular intervention to reduce sedentary behavior (SB) in office settings. However, the extent and distribution of SB in office workers long-term accustomed to using sit-stand workstations as a natural part of their work environment are largely unknown. In the present study, we aimed to describe patterns of SB in office workers with long-term access to sit-stand workstations and to determine the extent to which these patterns vary between days and workers.

METHODS

SB was objectively monitored using thigh-worn accelerometers for a full week in 24 office workers who had been equipped with a sit-stand workstation for at least 10 months. A comprehensive set of variables describing SB was calculated for each workday and worker, and distributions of these variables between days and workers were examined.

RESULTS

On average, workers spent 68% work time sitting [standard deviation (SD) between workers and between days (within worker): 10.4 and 18.2%]; workers changed from sitting to standing/walking 3.2 times per hour (SDs 0.6 and 1.2 h-1); with bouts of sitting being 14.9 min long (SDs 4.2 and 8.5 min). About one-third of the workers spent >75% of their workday sitting. Between-workers variability was significantly different from zero only for percent work time sitting, while between-days (within-worker) variability was substantial for all SB variables.

CONCLUSIONS

Office workers accustomed to using sit-stand workstations showed homogeneous patterns of SB when averaged across several days, except for percent work time seated. However, SB differed substantially between days for any individual worker. The finding that many workers were extensively sedentary suggests that just access to sit-stand workstations may not be a sufficient remedy against SB; additional personalized interventions reinforcing use may be needed. To this end, differences in SB between days should be acknowledged as a potentially valuable source of variation.

The DPhacto cohort: An overview of technically measured physical activity at work and leisure in blue-collar sectors for practitioners and researchers

For improved prevention of health issues among blue-collar workers, there is a need for an overview of the physical activity at work and leisure using technical long-term measurements in blue-collar sectors investigation of differences between the sectors. Thus, the objective of this paper was to provide an overview and investigate differences in physical activities and body postures at work and leisure among blue-collar sectors. The Dphacto cohort consists of 1087 workers from manufacturing, transportation and cleaning sectors (901 blue-collar and 186 white-collar workers) in Denmark. Eligible workers provided physical activity and heart rate measurements over several days with follow-up on health-related outcomes by self-report and registers. Considerable differences in sitting, standing, time on feet (walking, shuffling and standing combined) and forward bending of the back were found between work and leisure, and between the sectors. This overview of physical activity at work and leisure can be useful for better prevention of work-related health issues among blue-collar workers.

Technically measured compositional physical work demands and prospective register-based sickness absence (PODESA): a study protocol

BACKGROUND

Various physical work demands are shown to be associated with sickness absence. However, these studies have: (a) predominantly used self-reported data on physical work demands that have been shown to be inaccurate compared with technical measurements, (b) principally focused on various physical work demands in 'isolation', i.e. ignoring their co-dependency - compositional nature -, and (c) mainly used register data on long-term sickness absence. The present article describes the protocol of a study with the objective of investigating the association between technically measured compositional data on physical work demands and prospective long- and short-term register-based data on sickness absence.

METHODS

'The technically measured compositional Physical wOrk DEmands and prospective association with register-based Sickness Absence study (PODESA)' comprises data from two Danish cohorts (NOMAD and DPhacto) primarily on blue-collar workers. In the PODESA cohort, data on 1108 workers were collected at baseline (between 2011 and 2014). The cohort data comprise, e.g., self-reported information on descriptives, lifestyle, workday, and health, as well as accelerometer-based measurements of physical work demands (physical activity, movements, and postures). These baseline measurements are linked with prospective register-based data on sickness absence for up to four years after baseline. The prospective association between physical work demands and sickness absence will be analysed using a Compositional Data Analysis approach.

DISCUSSION

PODESA provides a unique possibility of unravelling which combinations of physical work demands are associated with prospective sickness absence. PODESA employs technically measured information on physical work demands (taking into account the compositionality of physical work demand data) and prospective sickness absence data. The findings from PODESA can be used to develop strengthened preventive interventions for sickness absence. Results are expected in 2019-2021.

Objectively Measured Sitting and Standing in Workers: Cross-Sectional Relationship with Autonomic Cardiac Modulation

Excessive sitting and standing are proposed risk factors for cardiovascular diseases (CVDs), possibly due to autonomic imbalance. This study examines the association of objectively measured sitting and standing with nocturnal autonomic cardiac modulation. The cross-sectional study examined 490 blue-collar workers in three Danish occupational sectors. Sitting and standing during work and leisure were assessed during 1⁻5 days using accelerometers. Heart rate (HR) and heart rate variability (HRV) were obtained during nocturnal sleep as markers of resting autonomic modulation. The associations of sitting and standing still (h/day) with HR and HRV were assessed with linear regression models, adjusted for age, gender, body mass index, smoking, and physical activity. More sitting time during leisure was associated with elevated HR (p = 0.02), and showed a trend towards reduced HRV. More standing time at work was associated with lower HR (p = 0.02), and with increased parasympathetic indices of HRV (root mean squared successive differences of R-R intervals p = 0.05; high-frequency power p = 0.07). These findings, while cross-sectional and restricted to blue-collar workers, suggest that sitting at leisure is detrimental to autonomic cardiac modulation, but standing at work is beneficial. However, the small effect size is likely insufficient to mitigate the previously shown detrimental effects of prolonged standing on CVD.

Are accelerometer measures of temporal patterns of static standing associated with lower extremity pain among blue-collar workers?

BACKGROUND

Pain in the lower extremities is common among blue-collar workers, with prolonged static standing as a potential risk factor. However, little is known about the association between diurnal accelerometer measures of static standing and pain in the lower extremities, and the potential importance of temporal patterns of static standing for this association.

RESEARCH QUESTION

We aimed to investigate the cross-sectional association between accelerometer measures of total static standing time and temporal patterns (bout duration) of static standing (short: 0-5 min; moderate: >5-10 min; and long bouts: >10 min) during total day, work and leisure and pain intensity (on a 0-10 scale) in hips, knees and feet/ankles.

METHODS

Accelerometers were used to measure static standing during four consecutive days among 677 blue-collar workers. Linear regression analyses were used to investigate the association between static standing time and pain intensity in the lower extremities.

RESULTS

Total static standing time comprised, on average, 3.9 h per day. 72.6% of the workers were exposed to long bouts of static standing, averaging 0.1 h per day. Short bouts of static standing were positively associated with hip and knee pain during total day, and positively associated with knee pain during work. Also, total static standing time during leisure was positively associated with knee and hip pain. A negative, but not significant, association was found for static standing in moderate bouts at work and hip pain.

SIGNIFICANCE

Even though the associations found were weak, these findings suggest that the temporal pattern of static standing is of importance for pain in the lower extremities. Future research should examine the possibility that moderate bouts of standing could play a role in preventing lower extremity pain.

Effect of different operationalizations of sedentary behavior in people with chronic stroke

Purpose: Sedentary behavior is common in people with stroke and has devastating impact on their health. Quantifying it is important to provide people with stroke with adequate physical behavior recommendations. Sedentary behavior can be quantified in terms of posture (sitting) or intensity (low energy expenditure). We compared the effect of different operationalizations of sedentary behavior on sedentary behavior outcomes (total time; way of accumulation) in people with stroke.Methods: Sedentary behavior was analyzed in 44 people with chronic stroke with an activity monitor that measured both body postures and movement intensity. It was operationalized as: (1) combining postural and intensity data; (2) using only postural data; (3) using only intensity data. For each operationalization, we quantified a set of outcomes. Repeated measures ANOVA and Bland-Altman plots were used to compare the operationalizations.Results: All sedentary behavior outcomes differed significantly between all operationalizations (p < 0.01). Bland-Altman plots showed large limits of agreement for all outcomes, showing large individual differences between operationalizations.Conclusions: Although it was neither possible nor our aim to investigate the validity of the two-component definition of sedentary behavior, our study shows that the type of operationalization of sedentary behavior significantly influences sedentary behavior outcomes in people with stroke.Implications for RehabilitationReliable assessment of sedentary behavior after stroke is important in order to provide adequate physical behavior recommendations for people with stroke.Sedentary behavior can be operationalized in terms of body posture (sitting time) or in terms of movement intensity (time <1.5 MET) or as a combination of both criteria; this study reveals that the type of operationalization affects the different outcome measures used to quantify sedentary behavior.Comparing sedentary behavior outcomes requires caution and should only be done when sedentary behavior is operationalized in the same way.

The association between occupational standing and sedentary leisure time over consecutive workdays among blue-collar workers in manual jobs

PURPOSE

Blue-collar workers spend much leisure time sedentary, which is associated with numerous health impairments. The extensive sedentary leisure time among blue-collar workers could be caused by fatigue from physically demanding work, like stationary standing. Occupational stationary standing is prevalent in many blue-collar jobs and has been shown to induce fatigue. The objective of this study was to investigate the association between occupational standing and sedentary leisure time over several workdays among blue-collar workers.

METHODS

This study used data from 925 workers from Danish workplaces within cleaning, transportation, manufacturing, construction, road maintenance, garbage disposal, and health service. Eligible workers wore accelerometers for 2-5 consecutive workdays. A linear regression was used to investigate the association between percent of work time spent standing and leisure time spent sedentary. A multilevel growth model was used to assess the association between standing during work and sedentary leisure time over consecutive workdays.

RESULTS

We found no association between percent of work hours spent standing and percent of leisure time spent sedentary (coef. = 0.01, p = 0.84). The results showed an increase in the workers' sedentary leisure time over a week (coef. = 0.70, p < 0.01). However, this increase was not associated with consecutive workdays exposed to occupational standing (coef. = 0.02, p = 0.42).

CONCLUSION

In this study, we found no support of a positive association between occupational standing and sedentary leisure time. This lack of association could be attributable to a low variation in sedentary leisure time or the chosen definition and measurement of occupational standing.

Association between objectively measured static standing and low back pain - a cross-sectional study among blue-collar workers

This study aims to investigate the cross-sectional association between objectively measured total time and temporal patterns of static standing (short bouts: 0-5 min; moderate bouts: >5-10 min; and long bouts: >10 min) during work and leisure and low back pain (LBP) among 698 blue-collar workers. Workers reported LBP on a 0-10 scale. The association between time spent on static standing and LBP was tested with linear regression. A positive association with LBP intensity was found for long bouts of static standing (β = 0.27) during total day (work + leisure), and total static standing time at leisure (β = 0.12). No significant associations were found for static standing during work and LBP intensity. These findings indicate that particularly long bouts of static standing over the entire day contribute to LBP in blue-collar workers. Practitioner Summary: The association between LBP and static standing time was investigated. This study indicates that prolonged time standing during total day and standing during leisure are positively associated with LBP among blue-collar workers. Therefore, practitioners should consider long periods of standing as a potential risk factor for LBP.

Improving work for the body - a participatory ergonomic intervention aiming at reducing physical exertion and musculoskeletal pain among childcare workers (the TOY-project): study protocol for a wait-list cluster-randomized controlled trial

Background

The prevalence of musculoskeletal pain (MSP) is persistently high throughout the world. Work-related factors such as high physical workload (lifting, bending and twisting of the back) are considered to be among the main causes of MSP. Work in childcare includes the need to lift, carry, and support children in a range of activities, requiring several demanding postures and movements, such as bending forward and twisting of the back and sitting on the floor. Participatory ergonomics may represent a solution for decreasing the physical workload to reduce MSP. We present the protocol of a study aiming to evaluate the effect and process of a participatory ergonomics intervention designed to reduce physical exertion during work and MSP (including MSP interfering with work) among childcare workers.

Methods/design

This study will use a two-arm cluster-randomized design employing a wait-list control, with childcare institutions forming the clusters. Three workshops will be conducted during the 4-month intervention period. Participants will identify risk factors for strenuous work and MSP, develop solutions for reducing the identified risk factors, and implement them in their team. An ergonomic consultant will guide the process. The data collection will consist of questionnaires and objective measures of heart rate and physical activity, observations of physical workload, and information on sickness absence based on company records. Primary outcomes are physical exertion during work and MSP (including pain-related work interference) measured at 4 months. Secondary outcomes measured at 4 months are sickness absence due to MSP; objectively measured occupational physical activity and heart rate; and self-reported self-efficacy, employee involvement, and need for recovery. Alongside the trial, a process evaluation and an economic evaluation will be conducted.

Discussion

The study will evaluate the effect and process of a participatory ergonomics intervention to reduce physical exertion at work and MSP among childcare workers. By performing a cluster-randomized controlled trial with an effect evaluation based on both objective and self-reported measures with the addition of a process evaluation and economic evaluation, this study will contribute to the evidence for prevention of MSP among a less studied occupational group. Results are expected in 2018–2019.

Trial registration

ISRCTN, ISRCTN10928313. Registered on 11 January 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2788-z) contains supplementary material, which is available to authorized users.

Does Physically Demanding Work Hinder a Physically Active Lifestyle in Low Socioeconomic Workers? A Compositional Data Analysis Based on Accelerometer Data

Leisure time physical activity (LTPA) is strongly associated with socioeconomic position (SEP). Few studies have investigated if demanding occupational physical activity (OPA) could impede a physically active lifestyle in low SEP groups. The aim of this study was to investigate the association between OPA and LTPA among low SEP men and women. We used cross-sectional data from 895 low SEP workers who wore accelerometers for 1–5 consecutive workdays. The associations between the relative importance of activities performed during work and leisure time were assessed using compositional regression models stratified on sex. Compositional isotemporal substitution models were used to assess the implication of increasing occupational walking, standing, or sitting on LTPA. We found dissimilarity in LTPA between the sexes, with men spending more waking leisure time sedentary than women (men ~67%, women ~61%), suggesting women performed more household tasks. In men, the associations between OPA and LTPA were weak. In women, the strongest association was observed between the relative importance of occupational walking and leisure time standing (β^ = −0.16; p = 0.01), where reallocating 15 min work time to occupational walking showed an expected decrease in leisure time standing of 7 min. If this time was spent on additional sedentary leisure time, it could have adverse health consequences.

Estimated impact of replacing sitting with standing at work on indicators of body composition: Cross-sectional and longitudinal findings using isotemporal substitution analysis on data from the Take a Stand! study

The purpose was to examine and compare the effects of replacing time spent sitting with standing at work on fat-free mass, fat mass and waist circumference using isotemporal substitution. Analyses were conducted on work hours on both cross-sectional and longitudinal data. The study included 223 persons from an intervention study aimed at reducing sitting time at work among office employees. Sitting, standing and anthropometry were measured objectively. Cross-sectional isotemporal substitution analyses were modelled on baseline data, while longitudinal analyses were modelled based on differences in sitting and standing time at work between baseline and 1-month follow-up in relation to differences in anthropometric measures between baseline and 3-months follow-up. Replacing one hour of sitting time with one hour of standing was associated with a 0.21 kg higher fat-free mass in the longitudinal analysis and 0.95 kg in the cross-sectional analysis. Fat mass was 0.32 kg lower in the longitudinal analysis and 0.61 kg lower in the cross-sectional analysis. Waist circumference decreased by 0.38 cm in the longitudinal analysis and 0.81 cm in the cross-sectional analysis. Both cross-sectional and longitudinal analyses showed an effect on body composition measures by replacing one hour of sitting with standing however, this effect was largest in the cross-sectional analyses.

Trial registration ClinicalTrials.gov NCT01996176.

Sitting patterns after relocation to activity-based offices: A controlled study of a natural intervention

This study determined the effect of relocating workers from traditional to activity-based offices on objectively measured sitting patterns. Office workers (n=493) from five office-sites within a large Swedish government agency were included in a controlled study of a natural intervention (2015-2017). At four sites, traditional offices were replaced by activity-based offices, while workers at one site with no relocation acted as controls. Sitting, standing and walking were measured objectively for 5-8days in a sub-sample (n=110) using accelerometry (Actigraph). Total sitting time (% of working time) and time spent in short (<5min), moderate (5-30min) and prolonged (>30min) uninterrupted periods in sitting were determined. Intervention effects were determined at 3- and 12-month follow-ups using linear mixed models adjusted for baseline age, gender and office type, and stratified by office-site (referencing controls). The relocation to activity-based offices did not result in an overall effect (across sites) on occupational sitting time (all p>0.05), while walking time had increased significantly by 1.4% of the working time at 12months compared with controls. Heterogeneous results were found across offices after 12months on total sitting time compared with controls (estimated change -18.3% time-1.4% time), prolonged sitting (change -18.3% to -3.8%), walking (change 0.5%-3.5%) and standing (change -1.4%-13.9%). In conclusion, relocation to activity-based offices had a limited overall effect on occupational sitting patterns in the studied organization, but differed considerably between office sites. Site-specific determinants of sitting behavior in activity-based offices need be identified.

Inter-rater reliability of direct observations of the physical and psychosocial working conditions in eldercare: An evaluation in the DOSES project

The aim of the study was to develop and evaluate the reliability of the "Danish observational study of eldercare work and musculoskeletal disorders" (DOSES) observation instrument to assess physical and psychosocial risk factors for musculoskeletal disorders (MSD) in eldercare work. During 1.5 years, sixteen raters conducted 117 inter-rater observations from 11 nursing homes. Reliability was evaluated using percent agreement and Gwet's AC1 coefficient. Of the 18 examined items, inter-rater reliability was excellent for 7 items (AC1>0.75) fair to good for 7 items (AC1 0.40-0.75) and poor for 2 items (AC1 0-0.40). For 2 items there was no agreement between the raters (AC1 <0). The reliability did not differ between the first and second half of the data collection period and the inter-rater observations were representative regarding occurrence of events in eldercare work. The instrument is appropriate for assessing physical and psychosocial risk factors for MSD among eldercare workers.

Take a Stand!-a multi-component intervention aimed at reducing sitting time among office workers-a cluster randomized trial

Background

Prolonged sitting time has been associated with adverse health outcomes. Interventions at work may contribute to reduced sitting. The objective was to test if a multicomponent work-based intervention can reduce sitting time and the number of prolonged sitting periods (> 30 min), increase the number of sit-to-stand transitions and decrease waist circumference and body fat percentage among office workers. Primary outcomes were: change in sitting time, prolonged sitting periods and sit-to-stand transitions at follow-up 1 month later.

Methods

At four workplaces, 19 offices (317 workers in total) were cluster randomized for intervention or control. The intervention included the appointment of local ambassadors, management support, environmental changes, a lecture and a workshop. Sitting time was measured using an ActiGraph GT3X+ fixed on the thigh. Data were processed using Acti4 software providing data on time spent sitting, standing and doing other activities. Control participants were instructed to behave as usual. Follow-up measurements were obtained after 1 and 3 months.

Results

At 1 and 3 months, total sitting time was 71 ( P < 0.001) and 48 min ( P < 0.001) lower per 8-h workday in the intervention group compared with the control group. At 1 month, the number of prolonged sitting periods was lower (-0.79/8-h workday, P < 0.001) and sit-to-stand transitions were higher (+14%/sitting hour, P = 0.001) in the intervention compared with the control group. After 3 months, trends persisted. The body fat percentage was lower by 0.61 percentage points ( P = 0.011) in the intervention group compared with the control group after 3 months.

Conclusions

The multicomponent workplace-based intervention was effective in reducing sitting time, prolonged sitting periods and body fat percentage, and in increasing the number of sit-to-stand transitions.

Correlation between the Oswestry Disability Index and objective measurements of walking capacity and performance in patients with lumbar spinal stenosis: a systematic literature review

PURPOSE

The Oswestry Disability Index (ODI) plays a significant role in lumbar spinal stenosis research and is used to assess patient's walking limitations. The World Health Organisation describes the constructs of walking capacity and performance and recommend measuring both to fully describe patient's walking ability. Objective methods to assess walking capacity and performance is being investigated and used alongside the traditional use of PROs. This review of the literature was made to provide an overview of relations between the ODI and outcome measures of walking capacity and performance in spinal stenosis research, and to provide a strategy for improving such measures in future research.

METHODS

The review was conducted according to the Prisma Statement. In February 2017, a search was performed in Pubmed, Embase and Cochrane database. Authors independently screened articles by title, abstract, and full text, and studies were included if both authors agreed. Articles with correlation analysis between the ODI, walking capacity and performance measures by accelerometer or GPS were included.

RESULTS

The results support a correlation between the ODI and walking capacity measures. The available studies using ODI and accelerometers were too few to reach a conclusion regarding correlation between ODI and walking performance. No articles with GPS measure were identified.

CONCLUSIONS

The ODI should not stand alone when evaluating walking limitations in patients with lumbar spinal stenosis. To enable a comprehensive assessment of walking ability, a walking test should be used to assess walking capacity and accelerometers should be investigated and standardized in measuring walking performance. These slides can be retrieved under Electronic Supplementary Material.

Acute effect on ambulatory blood pressure from aerobic exercise: a randomised cross-over study among female cleaners

Purpose

High occupational physical activity (OPA) is shown to increase the risk for elevated blood pressure, cardiovascular diseases and mortality. Conversely, aerobic exercise acutely lowers the blood pressure up to 25 h post exercise. However, it is unknown if this beneficial effect also apply for workers exposed to high levels of OPA. Cleaners constitute a relevant occupational group for this investigation because of a high prevalence of OPA and cardiovascular disease. Accordingly, the objective was to investigate the acute effects on ambulatory blood pressure from a single aerobic exercise session among female cleaners.

Methods

Twenty-two female cleaners were randomised to a cross-over study with a reference and an aerobic exercise session. Differences in 24-h, work hours, leisure time, and sleep ambulatory blood pressure (ABP) were evaluated using repeated measure 2 × 2 mixed-models.

Results

After the aerobic exercise session, the 24-h systolic ambulatory blood pressure was significantly lowered by 2.4 mmHg (p < 0.01) compared to the reference session. The 24-h diastolic ABP was unaltered. During work hours, a lowered systolic ABP of 2.2 mmHg (p = 0.02) and a higher diastolic ABP of 1.5 mmHg (p = 0.03) were found after the aerobic exercise session. During leisure time, the systolic ABP was lowered by 1.7 mmHg (p = 0.04) and the diastolic ABP was unaltered. During sleep, the systolic and diastolic ABP was unaltered.

Conclusion

A single aerobic exercise session lowered 24-h systolic ABP of 2.4 mmHg. Thus, an aerobic exercise session seems to be beneficial for lowering the risk of hypertension among cleaners.

Different autonomic responses to occupational and leisure time physical activities among blue-collar workers

Purpose

The differential effect of occupational and leisure time physical activity on cardiovascular health is termed the physical activity health paradox. Cardiac autonomic modulation could bring insights about the underlying mechanism behind this differential effect. The aim was to compare heart rate variability (HRV) during different activities (sitting, standing and moving) at work and leisure among blue-collar workers.

Methods

One hundred thirty-eight workers from the NOMAD cohort were included. Data from physical activity and HRV were obtained for 3–4 days using tri-axial accelerometers (Actigraph GT3X+) and a heart rate monitor (Actiheart). HRV indices were determined during sitting, standing and moving both at work and leisure. Linear mixed-models with two fixed factors (activities and domains) were applied to investigate differences in HRV indices adjusting for individual and occupational factors.

Results

The results showed significant effects of domain (p < 0.01), physical activity type (p < 0.01) and interaction between domain and activity type (p < 0.01) on HRV indices. Mean heart rate (IBI) and parasympathetic measures of HRV (RMSSD and HF) were lower for sitting (p < 0.01) and higher for moving (p < 0.01) during work compared with leisure, while no difference between domains was found for standing (p > 0.05). Sympathovagal balance (LF/HF) was higher during work for sitting and moving (p < 0.01), but showed no difference for standing (p = 0.62).

Conclusions

Differences in cardiac autonomic modulation between work and leisure were found, indicating sympathetic predominance during work and parasympathetic predominance during leisure for sitting. Autonomic responses can be part of the mechanism that explains the differential effect of occupational and leisure time physical activity on health.

On the health paradox of occupational and leisure-time physical activity using objective measurements: Effects on autonomic imbalance

OBJECTIVE

Leisure-time physical activity (LTPA) has considerable benefits for cardiovascular health and longevity, while occupational physical activity (OPA) is associated with an elevated cardiovascular risk. This "health paradox" may be explained by different effects on the autonomic nervous system from OPA and LTPA. Thus, we aimed to investigate whether objectively measured OPA and LTPA are differentially associated with autonomic regulation among workers.

METHODS

The study comprised 514 blue-collar workers from the Danish cohort DPHACTO. Physical activity (i.e. walking, climbing stairs, running and cycling) was assessed objectively using accelerometers worn on the thigh, hip and trunk over multiple working days. During this period, a heart rate monitor was used to sample heart period intervals from the ECG signal. Heart rate and heart rate variability (HRV) indices were analyzed during nocturnal sleep as markers of autonomic regulation. Multiple regression analysis was used to determine the main effects of OPA and LTPA and their interaction on heart rate and HRV, adjusting for multiple confounders.

RESULTS

Statistically significant interaction was found between OPA and LTPA on heart rate (adjusted p<0.0001) and HRV indices in time (rMSSD, adjusted p = 0.004) and frequency-domains (HF, adjusted p = 0.022; LF, adjusted p = 0.033). The beneficial effect of LTPA on nocturnal heart rate and HRV clearly diminished with higher levels of OPA, and high levels of both OPA and LTPA had a detrimental effect.

CONCLUSION

We found contrasting associations for objectively measured OPA and LTPA with heart rate and HRV during sleep. Differential effects of OPA and LTPA on autonomic regulation may contribute to the physical activity health paradox.

Objectively measured physical activity and 12-month trajectories of neck–shoulder pain in workers: A prospective study in DPHACTO

Aims: This study aimed to investigate the association between objectively measured physical activity at work and leisure and the intensity (mean level and time course) of neck–shoulder pain (NSP) over 12 months among male and female blue collar workers. Methods: Data were obtained from 625 blue collar workers from the Danish cohort DPHACTO. Physical activity was measured objectively at baseline using accelerometers. The percentage of time spent in physical activity (walking, climbing stairs, running and cycling) was calculated for both work and leisure time. Longitudinal data on the intensity of NSP (numerical rating scale 0–10) were collected using text messages every fourth week over 12 months. Linear mixed models were used to investigate the associations between occupational physical activity (OPA) and leisure time physical activity (LTPA) and the trajectories of the intensity of NSP, adjusted for individual, biomechanical and psychosocial factors, and baseline pain. Results: OPA was not associated with the mean intensity of NSP over 12 months. LTPA was negatively associated with the mean intensity of NSP both among men ( B=−0.71, 95% CI −1.31 to −0.11) and women ( B=−0.85, 95% CI −1.57 to −0.13). Sex interactions on the 12-month trajectories of NSP showed that higher physical activity was associated with a slower reduction in NSP among men for OPA only ( B=0.03, 95% CI 0.01-0.05) and women for LTPA only ( B=0.05, 95% CI 0.00-0.09). Conclusions: We found that more time in LTPA was associated with a lower overall intensity of NSP over 12 months among blue collar workers. However, depending on sex and domain, high physical activity had an unfavourable effect on the course of NSP over 12 months.

Association of objectively measured occupational walking and standing still with low back pain: a cross-sectional study

OBJECTIVES

This cross-sectional study investigated the association of objectively measured walking and standing still time at work with low back pain (LBP) intensity among blue-collar workers.

DESIGN

A cross-sectional study.

METHODS

187 workers attached two accelerometers for diurnal standing still and walking measurements, which were categorised using tertiles. Workers' self-reported LBP intensity (scale 0-9) was categorised into low (0-5) and high pain (6-9).

RESULTS

Of the 187 workers, 17% reported a high level of LBP. Results of the multi-adjusted logistic regression analysis demonstrated a negative association between walking and high LBP intensity (OR 0.24 CL 95% 0.07 to 0.79). The results between standing still and high LBP intensity were mixed and non-significant.

CONCLUSION

Blue-collar workers who walk more at work tend to have low LBP. These results should be verified using objective measures in a prospective design. Practitioner Summary: Most studies on the association of occupational walking and standing still with LBP have used poor self-reported measures. This study investigated the association of objectively measured time spent walking and standing still at work with LBP among blue-collar workers. A significant negative association between walking and LBP was found. However, because of the cross-sectional design, these results should be further investigated in prospective studies.

The variability of the trunk forward bending in standing activities during work vs. leisure time

High level of occupational physical activity (PA), contrary to leisure time activities, is generally associated with detrimental health outcomes. We hypothesized that this contrast may be associated with a different pattern of exposure variability in PA, e.g., forward bending of the trunk. The study was conducted on 657 blue-collar workers. Two accelerometers were used to identify the body posture and forward bending of the trunk during work and leisure time. The pattern of forward bending was analyzed using exposure variation analysis (EVA). The recordings comprised of 2.6 ± 0.97 working days in average, with 19.9 ± 8.1 h work and 22.9 ± 8.9 h leisure. The standard deviation and entropy of the EVA profile indicated 11% and 6% (for about 80% of subjects) less variable pattern during work compared with the leisure time, respectively. These new findings contribute to the understanding the paradoxical outcomes of PA during work and leisure.

Comparison between Mother, ActiGraph wGT3X-BT, and a hand tally for measuring steps at various walking speeds under controlled conditions

Introduction

Walking is endorsed as health enhancing and is the most common type of physical activity among older adults. Accelerometers are superior to self-reports when measuring steps, however, if they are to be used by clinicians the validity is of great importance. The aim of this study was to investigate the criterion validity of Mother and ActiGraph wGT3X-BT in measuring steps by comparing the devices to a hand tally under controlled conditions in healthy participants.

Methods

Thirty healthy participants were fitted with a belt containing the sensor of Mother (Motion Cookie) and ActiGraph. Participants walked on a treadmill for two minutes at each of the following speeds; 3.2, 4.8, and 6.4 km/h. The treadmill walking was video recorded and actual steps were subsequently determined by using a hand tally. Wilcoxon’s signed ranks test was used to determine whether Mother and ActiGraph measured an identical number of steps compared to the hand tally. Intraclass correlation coefficients were calculated to determine the relationship and Root Mean Square error was calculated to investigate the average error between the devices and the hand tally. Percent differences (PD) were calculated for between-instrument agreement (Mother vs. the hand tally and ActiGraph vs. the hand tally) and PDs below 3% were interpreted as acceptable and clinically irrelevant.

Results

Mother and ActiGraph under-counted steps significantly compared to the hand tally at all walking speeds (p < 0.001). Mother had a median of total differences of 9.5 steps (IQR = 10) and ActiGraph 59 steps (IQR = 77). Mother had smaller PDs at all speeds especially at 3.2 km/h (2.5% compared to 26.7%). Mother showed excellent ICC values ≥0.88 (0.51–0.96) at all speeds whilst ActiGraph had poor and fair to good ICC values ranging from 0.03 (−0.09–0.21) at a speed of 3.2 km/h to 0.64 (0.16–0.84) at a speed of 6.4 km/h.

Conclusion

Mother provides valid measures of steps at walking speeds of 3.2, 4.8, and 6.4 km/h with clinically irrelevant deviations compared to a hand tally while ActiGraph only provides valid measurements at 6.4 km/h based on the 3% criterion. These results have significant potential for valid objective measurements of low walking speeds. However, further research should investigate the validity of Mother in patients at even slower walking speeds and in free-living conditions.

Intra-individual variability in day-to-day and month-to-month measurements of physical activity and sedentary behaviour at work and in leisure-time among Danish adults

Background

Accelerometers can obtain precise measurements of movements during the day. However, the individual activity pattern varies from day-to-day and there is limited evidence on measurement days needed to obtain sufficient reliability. The aim of this study was to examine variability in accelerometer derived data on sedentary behaviour and physical activity at work and in leisure-time during week days among Danish office employees.

Methods

We included control participants (n = 135) from the Take a Stand! Intervention; a cluster randomized controlled trial conducted in 19 offices. Sitting time and physical activity were measured using an ActiGraph GT3X+ fixed on the thigh and data were processed using Acti4 software. Variability was examined for sitting time, standing time, steps and time spent in moderate-to-vigorous physical activity (MVPA) per day by multilevel mixed linear regression modelling.

Results

Results of this study showed that the number of days needed to obtain a reliability of 80% when measuring sitting time was 4.7 days for work and 5.5 days for leisure time. For physical activity at work, 4.0 days and 4.2 days were required to measure steps and MVPA, respectively. During leisure time, more monitoring time was needed to reliably estimate physical activity (6.8 days for steps and 5.8 days for MVPA).

Conclusions

The number of measurement days needed to reliably estimate activity patterns was greater for leisure time than for work time. The domain specific variability is of great importance to researchers and health promotion workers planning to use objective measures of sedentary behaviour and physical activity.

Trial registration

Clinical trials NCT01996176.

Is prolonged sitting at work associated with the time course of neck-shoulder pain? A prospective study in Danish blue-collar workers

OBJECTIVES

This study aimed to determine the extent to which objectively measured sitting time at work is associated with the course of neck-shoulder pain across 1 year in blue-collar workers.

METHODS

Data were analysed from 625 blue-collar workers in the Danish PHysical ACTivity cohort with Objective measurements (DPHACTO) cohort study (2012-2013). Objective data on sitting time were collected at baseline using accelerometry. Self-reported pain intensity (numeric rating scale 0-10) in the neck-shoulder region was registered for 1 year using repeated text messages (14 in total). Linear mixed models were used to determine the relationship between per cent time in sitting at work and trajectories of neck-shoulder pain, with and without adjustment for demographic, occupational and lifestyle factors, and baseline pain intensity.

RESULTS

More sitting time at work was associated with a faster decline in pain intensity over 12 months, as indicated by a statistically significant effect of sitting on pain trajectories in the crude (p=0.020) and fully adjusted models (p=0.027).

CONCLUSIONS

In blue-collar workers, more sitting time at work was associated with a favourable development of pain intensity over time. The relationship between sitting at work and pain needs further investigation before explicit recommendations and guidelines on sedentary behaviour among blue-collar workers can be developed.

Validity of Questionnaire and Representativeness of Objective Methods for Measurements of Mechanical Exposures in Construction and Health Care Work

Objectives

To determine the criterion validity of a questionnaire on physical exposures compared to objective measurements at construction and health care sites and to examine exposure variation over several working days.

Methods

Five hundred ninety-four construction and health care workers answered a baseline questionnaire. The daily activities (standing, moving, sitting, number of steps), postures (inclination of the arm and the trunk), and relative heart rate of 125 participants were recorded continuously over 3–4 working days. At the end of the first measurement day, the participants answered a second questionnaire (workday questionnaire).

Results

All objective activity measurements had significant correlations to their respective questions. Among health care workers, there were no correlations between postures and relative heart rate and the baseline questionnaire. The questionnaires overestimated the exposure durations. The highest explained variance in the adjusted models with self-reported variables were found for objectively measured sitting (R² = 0.559) and arm inclination > 60° (R² = 0.420). Objective measurements over several days showed a higher reliability compared to single day measurements.

Conclusions

Questionnaires cannot provide an accurate description of mechanical exposures. Objective measurements over several days are recommended in occupations with varying tasks.

Temporal patterns of sitting at work are associated with neck-shoulder pain in blue-collar workers: a cross-sectional analysis of accelerometer data in the DPHACTO study

Background

Our aim was to examine the extent to which temporal patterns of sitting during occupational work and during leisure-time, assessed using accelerometry, are associated with intense neck–shoulder pain (NSP) in blue-collar workers.

Methods

The population consisted of 659 Danish blue-collar workers. Accelerometers were attached to the thigh, hip, trunk and upper dominant arm to measure sitting time and physical activity across four consecutive days. Temporal sitting patterns were expressed separately for work and leisure by the proportion of total time spent sitting in brief bursts (0–5 min), moderate (>5–20 min) and prolonged (>20 min) periods. The peak NSP intensity during the previous 3 months was assessed using a numerical rating scale (range 0–10) and dichotomized into a lower (≤4) and higher (>4) NSP score. Logistic regression analyses with multiple adjustments for individual and occupational factors were performed to determine the association between brief, moderate and prolonged sitting periods, and NSP intensity.

Results

Time in brief bursts of occupational sitting was negatively associated with NSP intensity (adjusted OR 0.68, 95 % CI 0.48–0.98), while time in moderate periods of occupational sitting showed a positive association with NSP (adjusted OR 1.32, 95 % CI 1.04–1.69). Time in prolonged periods of occupational sitting was not associated with NSP (adjusted OR 0.78, 95 % CI 0.78–1.09). We found no significant association between brief, moderate or prolonged sitting periods during leisure, and NSP.

Conclusion

Our findings indicate that the association between occupational sitting time and intense NSP among blue-collar workers is sensitive to the temporal pattern of sitting.

Prolonged Sitting is Associated with Attenuated Heart Rate Variability during Sleep in Blue-Collar Workers

Prolonged sitting is associated with increased risk for cardiovascular diseases and mortality. However, research into the physiological determinants underlying this relationship is still in its infancy. The aim of the study was to determine the extent to which occupational and leisure-time sitting are associated with nocturnal heart rate variability (HRV) in blue-collar workers. The study included 138 blue-collar workers (mean age 45.5 (SD 9.4) years). Sitting-time was measured objectively for four days using tri-axial accelerometers (Actigraph GT3X+) worn on the thigh and trunk. During the same period, a heart rate monitor (Actiheart) was used to sample R-R intervals from the electrocardiogram. Time and frequency domain indices of HRV were only derived during nighttime sleep, and used as markers of cardiac autonomic modulation. Regression analyses with multiple adjustments (age, gender, body mass index, smoking, job-seniority, physical work-load, influence at work, and moderate-to-vigorous physical activity) were used to investigate the association between sitting time and nocturnal HRV. We found that occupational sitting-time was negatively associated (p < 0.05) with time and frequency domain HRV indices. Sitting-time explained up to 6% of the variance in HRV, independent of the covariates. Leisure-time sitting was not significantly associated with any HRV indices (p > 0.05). In conclusion, objectively measured occupational sitting-time was associated with reduced nocturnal HRV in blue-collar workers. This indicates an attenuated cardiac autonomic regulation with increasing sitting-time at work regardless of moderate-to-vigorous physical activity. The implications of this association for cardiovascular disease risk warrant further investigation via long-term prospective studies and intervention studies.

Differences between work and leisure in temporal patterns of objectively measured physical activity among blue-collar workers

Background

Leisure time physical activity (LTPA) is generally associated with favorable cardiovascular health outcomes, while occupational physical activity (OPA) shows less clear, or even opposite, cardiovascular effects. This apparent paradox is not sufficiently understood, but differences in temporal patterns of OPA and LTPA have been suggested as one explanation. Our aim was to investigate the extent to which work and leisure (non-occupational time) differ in temporal activity patterns among blue-collar workers, and to assess the modification of these patterns by age and gender.

Methods

This study was conducted on a cross-sectional sample of male (n = 108) and female (n = 83) blue-collar workers, aged between 21 and 65 years. Physical activity and sedentary behavior were assessed using accelerometers (Actigraph GT3X+) worn on the thigh and trunk for four consecutive days. Temporal patterns of OPA and LTPA were retrieved using Exposure Variation Analysis (EVA), and expressed in terms of percentage of work and leisure time spent in uninterrupted periods of different durations (<1 min, 1–5 min, 5–10 min, 10–30 min, 30–60 min and > 60 min) of sitting, standing, and walking. Repeated measures ANOVA and linear regression analyses were used to test a) possible differences between OPA and LTPA in selected EVA derivatives, and b) the modification of these differences by age and gender.

Results

OPA showed a larger percentage time walking in brief (<5 min) periods [mean (SD): 33.4 % (12.2)], and less time in prolonged (>30 min) sitting [7.0 % (9.3)] than LTPA [walking 15.4 % (5.0); sitting 31.9 % (15.3)], even after adjustment for the difference between work and leisure in total time spent in each activity type. These marked differences in the temporal pattern of OPA and LTPA were modified by gender, but not age.

Conclusion

We found that the temporal patterns of OPA and LTPA among blue-collar workers were markedly different even after adjustment for total physical activity time, and that this difference was modified by gender. We recommend using EVA derivatives in future studies striving to disentangle the apparent paradoxical cardiovascular effect of physical activity at work and during leisure.