Relationship between cumulative exposure to occupational lifting throughout working life and risk of ischemic heart disease in men and women. The Copenhagen Aging and Midlife Biobank.

Ischemic heart disease (IHD) causes mortality and morbidity. High levels of occupational physical activity (OPA) increases IHD risk, and occupational lifting (OL) is suggested as a detrimental OPA exposure. This study investigated the association between accumulated OL throughout working life, and risk for IHD, and potential sex and hypertension differences. Data from Copenhagen Ageing and Midlife Biobank linked to register-based information on incident IHD during 9 years follow-up in the Danish National Patient Registry were included. The outcome was the odds of IHD from baseline (2009-2011) to end of follow-up (2018), among participants without IHD at baseline. Accumulated OL was assessed by linking occupational codes to a Job Exposure Matrix, creating a measure in ton-years (lifting 1,000 kg/day/year). Multivariable logistic regression tested associations between level of accumulated OL and IHD, among the 6,606 included individuals (68% men). During follow-up, 7.3% men and 3.6% women were hospitalized with IHD. Among all participants, the odds for IHD were 47% (OR 1.47, 95% CI 1.05-2.06) higher among those with ≥5 to <10 ton-years, 39% (OR 1.39, 95% CI 1.06-1.83) higher among those with ≥10 to <30 ton-years, and 62% (OR 1.62, 95% CI 1.18-2.22) higher among those with ≥30 ton-years, compared to no accumulated OL. However, these increased odds were in the same direction in the fully-adjusted model but statistically insignificant, ≥5 to <10 ton-years OR 1.28, 95% CI 0.88-1.88; ≥10 to <30 ton-years OR 1.20, 95% CI 0.85-1.69; and ≥30 ton-years OR 1.22, 95% CI 0.81-1.84. No statistically significant interactions, nor any associations, between OL and sex, or hypertension were seen.

The association between number of steps and the ambulatory blood pressure during leisure vs. work hours among cleaners.

PURPOSE: The physical activity paradox states occupational physical activity (OPA) to be hazardous and leisure time physical activity (LTPA) to be beneficial for health. Yet, the acute effects of OPA and LTPA on cardiovascular risk factors are sparsely investigated. The aim of this study was to investigate the acute effects on ambulatory blood pressure (ABP) from steps/hour during work and leisure time among cleaners. METHODS: Data were obtained from a cluster randomized worksite intervention among 91 cleaners in Denmark and included a questionnaire, objective physical measurements, ABP (measured across 24 h), and steps/hour (measured during work and leisure time). A preliminary linear regression analysis was conducted as a mixed model including random intercept and slope, allowing for both within- and between-participant variability. We adjusted for sex, age, job seniority, medication use, smoking, self-reported fitness and BMI. Changes in ABP (mmHg) were estimated per 100 steps/hour. RESULTS: The number of steps taken was not associated with ABP during either work or leisure. Moreover, the ABP did not seem to differ between exposure to steps taken during work (systolic - 0.42 mmHg, 95% Confidence Interval (CI): - 1.10-0.25, diastolic - 0.03 mmHg, 95% CI, - 0.45-0.39) and leisure time (systolic -0.47 mmHg, 95% CI, - 1.66-0.72, diastolic 0.25 mmHg, 95% CI, - 0.46-0.97). CONCLUSION: Our findings show no significant association between steps/hour and ABP and no contrasting effects between work and leisure time. These mechanisms fostering the divergent results need to be further investigated to improve the understanding of the physical activity paradox.

The association between physical activity, low-grade inflammation, and labour market attachment among people with multimorbidity: A cross-sectional study from the Lolland-Falster Health Study, Denmark.

Aim: Evidence suggests low-grade inflammation (LGI) to be associated with multimorbidity. Furthermore, there are links between inflammation markers, physical activity (PA), and labour market participation. The aims of this study were to examine the association between PA and LGI in people with multimorbidity and if this association was moderated by self-reported labour market attachment. Methods: Cross-sectional data were collected in the Lolland-Falster Health Study (LOFUS) from 2016-2020. We included 1,106 participants with multimorbidity and valid accelerometer data. PA was measured as the average counts per minute (CPM) per day during wake time and split in time spent in moderate to vigorous intensity (MVPA) and light intensity (LPA). Degree of inflammation was determined by high sensitive C-reactive protein (hsCRP) level. Associations were investigated using multiple logistic regression analyses, stratified by labour market attachment. Results: The odds of having LGI was higher with lower amount of daily LPA. The highest odds of LGI was observed for CPM < 200 per day (odds ratio (OR) 2.55; 95% confidence interval (CI) 1.46-4.43), MVPA < 15 minutes per day (OR 2.97; 95 % CI 1.56-5.62), and LPA < 90 (OR 2.89; 95 % CI 1.43-5.81) with the reference groups being CPM ≥ 400 per day, MVPA ≥ 30, and LPA ≥ 180 min per day, respectively. We could not preclude an interaction between LPA and labour market attachment (p = 0.109). Conclusion: PA recommendations should be developed with attention to people with chronic diseases, who may experience barriers to reach PA at high intensities. People with no labour market attachment may benefit from primary and secondary prevention of multimorbidity.

An integrated approach to health, wellbeing, and productivity at work: a design of a stepped wedge worksite intervention study.

BACKGROUND: Despite an intensive focus on workers' health during recent decades, the prevalence of work-related diseases remains unchanged in Denmark and internationally. Therefore, USA and Australian researchers have initiated new paradigms for integration of health promotion, prevention of work-related disease, and organization of work. Inspired by the Australian WorkHealth Improvement Network program (WIN), this paper describes the background, design, intervention methodologies, and evaluation methods of an Integrated Approach to Health, Wellbeing, and Productivity at Work (ITASPA) intervention aiming to prevent work-related injuries and diseases and promote the health, safety, and wellbeing of the worker. METHODS: Using a stepped wedge design, worksites will be enrolled at baseline and offered the intervention starting at different times. Data will be collected at baseline, before the off-set of the intervention, and after each implementation period. The effect evaluation will be based on a mixed-methods approach. The qualitative data are based on semi-structured interviews and focus groups. The quantitative data consists of questionnaires, anthropometrics, and resting blood pressure and will be analyzed based on the intention-to-treat principle in linear mixed models with random slope and intercept. DISCUSSION: Integrated interventions are shown to increase overall health and safety at worksites more effectively and rapidly than more narrowly focused programs. Still, previous integrated interventions are lacking successful implementation. In ITASPA, the effects of the intervention is tested in a strong scientific mixed-methods design. Thus, the ITASPA project contributes to the knowledge about what characterizes a best practice for the implementation of integrated worksite interventions. TRIAL REGISTRATION: ITASPA is retrospectively registered in Clinicaltrials.gov on May 19, 2023 (NCT05866978).

Occupational physical activity predicts baseline and 8-year progression of carotid atherosclerosis among women.

INTRODUCTION: Recent reviews link higher levels of occupational physical activity (OPA) to cardiovascular disease (CVD). However, the evidence for women is inconsistent and studies of activity-limiting symptomatic CVD are prone to healthy worker survivor effect. To address these limitations, this study investigated OPA effects on asymptomatic carotid artery intima-media thickness (IMT) among women. METHODS: Participants include 905 women from the population-based Kuopio Ischemic Heart Disease Risk Factor Study with baseline (1998-2001) data on self-reported OPA and sonographic measurement of IMT. Linear mixed models with adjustment for 15 potential confounders estimated and compared mean baseline IMT and 8-year IMT progression for five levels of self-reported OPA. Analyses stratified by cardiovascular health and retirement status were planned because strong interactions between preexisting CVD and OPA intensity have previously been reported. RESULTS: Light standing work, moderately heavy active work, and heavy or very heavy physical work were all consistently associated with greater baseline IMT and 8-year IMT progression than light sitting work. The greatest baseline IMT was observed for heavy or very heavy physical work (1.21 mm), and the greatest 8-year IMT progression for light standing work and moderately heavy active work (both 0.13 mm), 30% above sitting work (0.10 mm). Stratified analyses showed that these differences were driven by much stronger OPA effects among women with baseline carotid artery stenosis. Retired women experienced slower IMT progression than those working at baseline. CONCLUSIONS: Higher levels of OPA predict higher baseline IMT and 8-year IMT progression, especially among women with baseline stenosis.

Translation and cross-cultural adaptation of the Work Rehabilitation Questionnaire (WORQ) into Danish.

Purpose: This study aimed to translate and cross-culturally adapt the work rehabilitation questionnaire (WORQ) into Danish to examine the internal consistency and test-retest reliability of the Danish WORQ and, second, to test the feasibility of WORQ in the Danish context of vocational rehabilitation. Methods: The translation was performed in a dual-panel approach. The panel consisted of a bilingual physician, a university student in psychology, a layperson, a specialist in social work and rehabilitation, and a professor in social medicine. The international classification of functioning, disability, and health (ICF) codes were cross-evaluated to secure that there was a high level of agreement of ICF codes for each specific WORQ item in the Danish and English version. The content validity was evaluated by the clinical physicians at an outpatient clinic in social medicine and by the case managers at a municipality job center. Data for the examination of the internal consistency and test-retest reliability were collected at the Holbæk municipality from citizens in the working age. The test-retest took place 14 days apart. The internal consistency and test-retest reliability were tested conducting Cronbach's alpha, intraclass correlation, and Spearman's correlation analyses. Results: The panel experienced only minor challenges in the translation process, leading to minor modifications. The cross-evaluation of coding in the Danish WORQ compared with the initial English version only found small deviations, while the remaining coding agreed between the initial English and the Danish items. The panel argued to add sub-codes to culturally adapt to the transportation forms generally used in Denmark. The general perception among the participating patients and citizens at the job center as well as the clinical physicians and case managers was that the WORQ was easy, understandable, and meaningful. Conclusions: This study showed that the Danish WORQ have a high content validity and usability. Nonetheless, the Danish WORQ needs to be validated against well-acknowledged tools for assessing functional ability specific to work and in general.

Construct validity of the Danish version of the Work Rehabilitation Questionnaire (WORQ)-sensitivity and specificity of the objectively tested physical capacity items.

Objective: The aim of this study was to examine the construct validity of the Danish version of the Work Rehabilitation Questionnaire (WORQ) and to compare the physical capacity items of WORQ to objective, standardized measures of physical capacity and selected SF-36 physical items. Methods: The study took place at a job center in Holbæk municipality, and 40 clients of working age were enrolled. Participants completed the interviewer-administered version of WORQ, selected SF-36 items, and underwent objective, physical capacity testing, including a 30-s sit-to-stand-test, a hand-grip-strength test, and a 6-min walk test to estimate cardiorespiratory fitness. Correlations between variables were assessed using Spearman's correlation. Further, cross tabulations and chi-square tests were conducted, and sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were calculated. Results: We found a moderate to strong correlation between WORQ and SF-36 items and a weak to moderate correlation between physical capacity items of WORQ and objectively tested physical capacity measures. On the basis of cross tabulations, calculations yielded overall higher NPVs than PPVs, whereas sensitivity and specificity varied more, with not one parameter being overall better than the other. Conclusion: We found evidence of construct validity of the WORQ-Danish. However, our study might also raise a question as to whether objective physical capacity tests are the gold standard for evaluating functioning. Our results are promising, and we suggest further investigations of the screening capabilities of WORQ, alongside other legacy measures or instruments, both self-reported and objective physical measures, to complement information-where specific answers to specific questions trigger work-related actions or interventions.

How Does Occupational Lifting Affect Ambulatory Blood Pressure, Relative Aerobic Workload and Level of Physical Activity?

INTRODUCTION: Occupational physical activity (OPA), including occupational lifting (OL), seems to increase the risk of cardiovascular disease (CVD). Knowledge about the association between OL and risk of CVD is sparse, but repeated OL is assumed to result in prolonged raised blood pressure and heart rate (HR) eventually augmenting the risk of CVD. To disentangle parts of the mechanisms behind the raised 24-hour ambulatory blood pressure measurement (24h-ABPM), by exposure to OL, this study aimed to explore the acute differences in 24h-ABPM, relative aerobic workload (RAW) and OPA across workdays with and without OL, and secondary to assess the feasibility and rater agreement of direct field observations of the frequency and load of occupational lifting. METHODS: This controlled cross-over study investigates associations between moderate to high OL and 24h-ABPM, RAW in per cent of heart rate reserve (%HRR) and level of OPA. This included 2x24h monitoring of 24h-ABPM (Spacelabs 90217), PA (Axivity) and HR (Actiheart), comprising a workday containing OL and a workday without. The frequency and burden of OL were directly observed in field. The data were time synchronized and processed in the Acti4 software. Differences across workdays with and without OL in 24h-ABPM, RAW and OPA were evaluated using repeated 2 × 2 mixed-models among 60 blue-collar workers in Denmark.. Exposure to OL was estimated by direct manual field observation, registering burden and frequency of OL. Interrater reliability tests were performed across 15 participants representing 7 occupational groups. Interclass correlation coefficient (ICC) estimates of total burden lifted and frequency of lifts were calculated, based on a mean-rating (k = 2), absolute-agreement, 2 way mixed-effects model, indicating the raters as fixed effects. RESULTS: OL led to non-significant increases in ABPM during work-time (systolic Δ1.79 mmHg, 95%CI -4.49-8.08, diastolic Δ0.43 mmHg, 95%CI -0.80-1.65), and on 24-hours basis (systolic Δ1.96 mmHg, 95%CI -3.80-7.72, diastolic Δ0.53 mmHg, 95%CI -3.12-4.18), significant increases in RAW during work (Δ7.74 %HRR, 95%CI 3.57-11.91) as well as a raised level of OPA (Δ4156.88 steps, 95%CI 1898.83-6414.93, Δ-0.67 hours of sitting time, 95%CI -1.25-0.10, Δ-0.52 hours of standing time, 95%CI -1.03-0.01, Δ0.48 hours of walking time, 95%CI 0.18-0.78). ICC estimates were 0.998 (95% CI 0.995-0.999) for total burden lifted and 0.992 (95% CI 0.975-0.997) for frequency of lift. DISCUSSION: OL increased both intensity and volume of OPA among blue-collar workers, which supposedly to contributes to an augmented risk of CVD. Although this study finds hazardous acute effects, further investigations are needed to evaluate the long-term effects of OL on ABPM, HR and volume of OPA, also effects of cumulative exposure to OL would be relevant to investigate. CONCLUSION: OL significantly raised the intensity and volume of OPA. Direct field observation of occupational lifting showed an excellent interrater reliability.

Prospective relationship between occupational physical activity and risk of ischaemic heart disease: are men and women differently affected?

AIMS: High occupational physical activity (OPA) seems to increase risk of cardiovascular diseases among men. However, findings are mixed, and it is not known if women are differently affected. Therefore, the aim of this study is to investigate the relationship between OPA and risk for ischaemic heart disease (IHD), and whether it differs across sex. METHODS AND RESULTS: This prospective cohort study was based on 1399 women and 1706 men, aged 30-61 years, participating in the Danish Monica 1 study in 1982-84, actively employed, without prior IHD and answering an OPA question. The information on incidence of IHD, before and during the 34-years follow-up, was retrieved by individual linkage to the Danish National Patient Registry. Cox proportional hazards models were used to investigate the association between OPA and IHD. Compared to women with sedentary work, women in all other OPA categories had lower hazard ratio (HR) for IHD. Among men, the risk of IHD was 22% higher among those with light OPA, and 42% and 46% higher among those with moderate OPA with some lifting or strenuous work with heavy lifting, respectively, compared to men with sedentary OPA. Compared to women with sedentary work, HR for IHD was higher among men in all OPA categories. There was statistically significant interaction between OPA and sex. CONCLUSION: Demanding or strenuous OPA seems to be a risk factor for IHD among men, whereas a higher level of OPA seems to protect women from IHD. This emphasizes the importance of taking sex differences into account in studies of health effects of OPA.

In the Danish Monica I study among 1399 women and 1706 men, we investigated whether high physical activity at work was associated with higher risk of ischaemic heart disease and whether this association was different among men and women. The association between occupational physical activity and ischaemic heart disease was different among men and women. High physical activity at work was associated with around 45% higher risk of ischaemic heart disease in men, but with around 65% lower risk in women. The underlying mechanisms for this difference, e.g. differences in exposure and physiology, should be further investigated in future studies.

Agreement between an expert-rated mini job exposure matrix of occupational biomechanical exposures to the lower body and technical measurements or observation: a method comparison study.

OBJECTIVES: Investigating the agreement between an expert-rated mini job exposure matrix (JEM) of lower body exposures and technical measurements of worktime spent standing/walking and observation-based estimates of time spent kneeling/squatting and total load lifted per workday. METHODS: We chose 16 job titles from the 121 job groups in the lower body JEM and included them in the mini JEM. New expert ratings for the mini JEM were performed by the same five occupational physicians who performed the ratings for the lower body JEM. For each job title and type of exposure, the exposure estimates were a mean of the five independent ratings. Technical measurements of standing/walking for all 16 job titles, and for 8 job titles workplace observations were performed of kneeling/squatting and total load lifted per workday. Data were collected from September to December 2015 and supplemented by data from the NOMAD and DPhacto studies collected between 2011 and 2013. All data were collected in Denmark. Agreement between expert-based and measured/observed lower body exposures by job titles was evaluated using Spearman's rank correlation, Bland-Altman plots evaluated systematic deviations and limits of agreement (LoA). RESULTS: Standing/walking showed a rank correlation of 0.55, kneeling/squatting 0.83 and total load lifted per workday 0.71. The mini JEM estimates did not systematically deviate from the technical measurements/observations for time spent standing/walking (mean difference 0.20 hours/workday, LoA -1.63, 2.03 hours/workday) and kneeling/squatting (mean difference -0.35 hours/workday, LoA -1.21, 0.51 hours/workday). For total load lifted per workday, the mini JEM systematically overestimated the exposures compared with the observations (mean difference -909 kg/workday, LoA -3000, 1147 kg/workday). CONCLUSIONS: There was moderate to very high agreement between an expert-rated mini JEM of standing/walking, kneeling/squatting, and lifting exposures and corresponding technical measurements/observations. This method comparison study supports the use of the expert-based lower body JEM in large-scale occupational epidemiological studies.

The physical activity health paradox and risk factors for cardiovascular disease: A cross-sectional compositional data analysis in the Copenhagen City Heart Study.

BACKGROUND: Studies indicate that physical activity during leisure and work have opposite associations with cardiovascular disease (CVD) risk factors, referred to as the physical activity health paradox. We investigated how sedentary behaviour and physical activity types during leisure and work are associated with systolic blood pressure (SBP), waist circumference (WC), and low-density lipoprotein cholesterol (LDL-C) in an adult general population sample using compositional data analysis. METHODS: Participants wore accelerometers for 7 days (right thigh and iliac crest; 24 h/day) and had their SBP, WC, and LDL-C measured. Accelerometer data was analysed using the software Acti4 to derive daily time spent in sedentary behaviour and physical activity types. The measure of association was quantified by reallocating time between sedentary behaviour and 1) walking, and 2) high-intensity physical activity (HIPA; sum of climbing stairs, running, cycling, and rowing), during both domains. RESULTS: In total, 652 participants were included in the analyses (median wear time: 6 days, 23.8 h/day). During leisure, the results indicated that less sedentary behaviour and more walking or more HIPA was associated with lower SBP, while during work, the findings indicated an association with higher SBP. During both domains, the findings indicated that less sedentary behaviour and more HIPA was associated with a smaller WC and lower LDL-C. However, the findings indicated less sedentary behaviour and more walking to be associated with a larger WC and higher LDL-C, regardless of domain. CONCLUSIONS: During leisure, less sedentary behaviour and more walking or HIPA seems to be associated with a lower SBP, but, during work, it seems to be associated with a higher SBP. No consistent differences between domains were observed for WC and LDL-C. These findings highlight the importance of considering the physical activity health paradox, at least for some risk factors for CVD.

Intensity of occupational physical activity in blue-collar workers: do self-reported rating and device-worn measurements agree?

PURPOSE: High intensity occupational physical activity (OPA) seem to aggravate health and increase risk of sick leave and early retirement. Most intensity of OPA monitoring has been self-reported, e.g. by rating of perceived exertion (RPE). However, no studies have investigated the precision and risk of bias in RPE reporting during free-living OPA. This study investigated the agreement between OPA intensity in percentage of the heart rate reserve (%HRR) estimated from RPE and device-measured heart rate (HR), and potential bias factors on this agreement. METHODS: The CR10 scale measured RPE at work. The Actiheart monitor measured HR during 24-h a day for 2-4 days. Both RPE and device-worn HR were converted to %HRR. The difference between both %HRR and their limits of agreement was determined in a Bland Altman plot. To detect bias factors, the difference between both %HRR was regressed on age, sex, cardiorespiratory fitness, occupational lifting, medication, consequences of musculoskeletal disorders and the interactions between these factors with device-work %HRR. RESULTS: Six hundred and twenty-three participants were included in the analysis. Mean difference between RPE-based and device-worn %HRR was 54.6% (SD 19.5). The limits of agreement were wide (11.6-90.1%HRR). Age (0.48%HRR, 95% CI 0.18-0.79) occupational lifting (9.84%HRR, 95% CI 3.85-15.83) and cardiorespiratory fitness (0.41%HRR, 95% CI 0.03-0.79) significantly biased the agreement between the estimations of OPA intensity. CONCLUSION: RPE overestimated OPA intensity, and was biased by several factors. Device-worn %HRR should be preferred when evaluating OPA intensity among workers with physically demanding jobs.

Association between exposure to heavy occupational lifting and cardiac structure and function: a cross-sectional analysis from the Copenhagen City Heart Study.

To investigate cross-sectional associations between heavy occupational lifting and cardiac structure and function. Participants from the 5th round of the Copenhagen City Heart Study, aged < 65 years old, answering a questionnaire regarding occupational physical activity, heavy occupational lifting, use of anti-hypertensive and heart medication, and data on blood pressure, cardiac structure and function, from an echocardiographic examination, were included. Adjusted linear regressions and logistic regressions were applied to estimate the cross-sectional association between heavy occupational lifting and cardiac structure and function across all included participants and in groups stratified by hypertension status, and the risk for having abnormal values of cardiac structure and function. 2511 participants were included. The cross-sectional standardized associations between heavy occupational lifting and measures of cardiac structure and function showed a trends for raised left ventricular mass index (LVMi) (ß 0.14, 99% CI - 0.03 to 0.31). The standardized associations stratified by hypertensive status showed significant associations between exposure to heavy occupational lifting and LVMi (ß 0.20, 99% CI - 0.002 to 0.40) and a trend of a raised end-diastolic interventricular septal thickness (IVSd) (ß 0.15, 99% CI - 0.03 to 0.33) among normotensives. Exposure to heavy occupational lifting increased the odds for an abnormal IVSd (OR 1.42, 99% CI 1.07-1.89). This cross-sectional study shows heavy occupational lifting to associate with indices of abnormal cardiac structure and function among normotensives, indicating an increased risk for cardiovascular disease.

Occupational lifting and risk of hypertension, stratified by use of anti-hypertensives and age - a cross-sectional and prospective cohort study.

BACKGROUND: Heavy occupational lifting is prevalent in the general working population and is sparsely reported to associate with hypertension, especially among older and hypertensive workers. We investigated if heavy occupational lifting is associated with hypertension and blood pressure (BP) in both cross-sectional and prospective study designs in the Copenhagen General Population Study, stratified by age, and use of anti-hypertensives. METHODS: Participation was conducted following the declaration of Helsinki and approved by the ethical committee (H-KF-01-144/01). By multivariable logistic and linear regression models, we investigated the association between heavy occupational lifting and hypertension, in a cross-sectional design (n = 67,363), using anti-hypertensives or BP ≥140/≥90 mmHg as outcome, and in a prospective design (n = 7020) with an above-median change in systolic BP (SBP) from baseline to follow-up and/or a shift from no use to use of anti-hypertensives as outcome, with and without stratification by age and use of anti-hypertensives. RESULTS: The odds ratio for hypertension was estimated at 0.97 (99% CI: 0.93-1.00) in the cross-sectional analysis, and at 1.08 (99% CI: 0.98-1.19) in the prospective analysis. The difference in SBP among workers with versus without heavy occupational lifting was estimated at - 0.29 mmHg (99% CI -0.82 - 0.25) in the cross-sectional and at 1.02 mmHg (99% CI -0.41 - 2.45) in the prospective analysis. No significant interaction between heavy occupational lifting and age, nor use of anti-hypertensives were shown. CONCLUSIONS: Only the prospective analysis indicated heavy occupational lifting to increase the risk of hypertension. Further research on the association between occupational lifting and hypertension are needed.

Heart rate during work and heart rate variability during the following night: a day-by-day investigation on the physical activity paradox among blue-collar workers.

OBJECTIVES: Contrary to leisure-time physical activity, occupational physical activity (OPA) may have harmful health effects, called the physical activity paradox. A proposed mechanism is that OPA can elevate the heart rate (HR) for several hours per day. We aimed to investigate the association between the mean intensity of OPA and HR variability (HRV) indices the following night. METHODS: Three cohorts (NOMAD, DPhacto, and Physical Workload and Fitness) involving blue-collar workers from different sectors were merged in this study. HR monitors (Actiheart) recorded 24-hour inter-beat intervals (IBI) for up to four consecutive days. The relative intensity of the mean HR during work was estimated by HR reserve (%HRR), and time-domain indices of HRV were analyzed during the following night. Data were analyzed using a multilevel growth model to test the association between mean %HRR during work and HRV indices at night in a day-by-day analysis adjusted for age, BMI, alcohol consumption, smoking, and occupation. RESULTS: The dataset included a sample of 959 Danish blue-collar workers, with a mean %HRR during work of 31%, and 42% worked at an intensity ≥30%HRR. The multilevel model showed negative within- and between-subject associations between %HRR during work and HRV indices at night. CONCLUSIONS: Our results indicate a higher %HRR during work to associate with lower HRV indices the following night and a higher HR, reflecting an imbalanced autonomic cardiac modulation. This finding supports a high mean HR during work to be a potential underlying mechanism for the harmful health effect of OPA.

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.

The Relation between Domain-Specific Physical Behaviour and Cardiorespiratory Fitness: A Cross-Sectional Compositional Data Analysis on the Physical Activity Health Paradox Using Accelerometer-Assessed Data.

In contrast to leisure time physical activity (LTPA), occupational physical activity (OPA) does not have similar beneficial health effects. These differential health effects might be explained by dissimilar effects of LTPA and OPA on cardiorespiratory fitness (CRF). This study investigated cross-sectional associations between different physical behaviours during both work and leisure time and CRF by using a Compositional Data Analysis approach. Physical behaviours were assessed by two accelerometers among 309 workers with various manual jobs. During work time, more sedentary behaviour (SB) was associated with higher CRF when compared relatively to time spent on other work behaviours, while more SB during leisure time was associated with lower CRF when compared to other leisure time behaviours. Reallocating more time to moderate-to-vigorous physical activity (MVPA) from the other behaviours within leisure time was positively associated with CRF, which was not the case for MVPA during work. The results of our study are in line with the physical activity health paradox and we call for further study on the interaction between LTPA and OPA by implementing device-worn measures in a longitudinal design. Our results highlight the need for recommendations to take into account the different effects of OPA and LTPA on CRF.

Frequency of obstructive sleep apnoea in Danish truck drivers.

INTRODUCTION: Obstructive sleep apnoea (OSA) is associated with excessive daytime sleepiness and therefore affects traffic safety. The risk factors for OSA are age and BMI, and therefore sedentary occupational groups are likely to have a high prevalence of OSA. Our aim was to investigate the prevalence and identify the risk factors for OSA and Type 2 diabetes (T2D) among occupational truck drivers in Denmark. METHODS: Occupational truck drivers were recruited and their pulse oximetry and nasal respiratory flow were measured with the ApneaLink device. The Apnea-Hypopnea Index (AHI), defined as the average number of apnoeas and hypopnoeas per hour of sleep, was used to classify 1) non OSA (AHI less-than 5/h), 2) mild OSA (5/h ≤ AHI less-than 15/h), 3) moderate OSA (15/h ≤ AHI ≤ 30/h) and 4) severe OSA (AHI > 30/h). Risk factors for OSA and T2D were investigated by linear and logistic regressions. RESULTS: A total of 57 of 97 drivers were included in the analysis, all of whom were men, and 56% had OSA. The linear regressions showed all of the evaluated risk factors to be positively associated (less-than 0.01) with the AHI score, supported by the estimated odds ratios of having above-recommended levels of the evaluated risk factors when classified as having OSA. CONCLUSIONS: All the evaluated risk factors were significantly associated with AHI, and the prevalence of OSA was above mean levels in the population. Confirmation of these results is warranted in future studies. FUNDING: This study was supported by unrestricted grants from The FDE foundation, The Danish Council for Safe Traffic and Nordsjaellands Hospital. TRIAL REGISTRATION: none.

Can we walk away from cardiovascular disease risk or do we have to 'huff and puff'? A cross-sectional compositional accelerometer data analysis among adults and older adults in the Copenhagen City Heart Study.

BACKGROUND: It is unclear whether walking can decrease cardiovascular disease (CVD) risk or if high intensity physical activity (HIPA) is needed, and whether the association is modified by age. We investigated how sedentary behaviour, walking, and HIPA, were associated with systolic blood pressure (SBP), waist circumference (WC), and low-density lipoprotein cholesterol (LDL-C) among adults and older adults in a general population sample using compositional data analysis. Specifically, the measure of association was quantified by reallocating time between sedentary behaviour and 1) walking, and 2) HIPA. METHODS: Cross-sectional data from the fifth examination of the Copenhagen City Heart Study was used. Using the software Acti4, we estimated daily time spent in physical behaviours from accelerometer data worn 24 h/day for 7 days (i.e., right frontal thigh and iliac crest; median wear time: 6 days, 23.8 h/day). SBP, WC, and LDL-C were measured during a physical examination. Inclusion criteria were ≥ 5 days with ≥16 h of accelerometer recordings per day, and no use of antihypertensives, diuretics or cholesterol lowering medicine. The 24-h physical behaviour composition consisted of sedentary behaviour, standing, moving, walking, HIPA (i.e., sum of climbing stairs, running, cycling, and rowing), and time in bed. We used fitted values from linear regression models to predict the difference in outcome given the investigated time reallocations relative to the group-specific mean composition. RESULTS: Among 1053 eligible participants, we found an interaction between the physical behaviour composition and age. Age-stratified analyses (i.e.,

Detection of kneeling and squatting during work using wireless triaxial accelerometers.

Occupational kneeling and squatting are well-documented risk factors for knee disorders. A method using 3 wireless accelerometers to detect and discriminate kneeling and squatting during work were developed based on data from a semi-standardised laboratory protocol. The method was tested for validity under free-living working conditions. The developed method showed high sensitivity (88-99%) and specificity (98-99%) for detection of kneeling and squatting during the semi-standardised laboratory conditions. During free-living working conditions, kneeling showed very high sensitivity (94%) and specificity (99%), while squatting results were non-conclusive due to limited duration of squatting during the free-living working conditions. This method shows great promise for long-term technical measurement of kneeling and squatting during normal working conditions using wireless accelerometers. The method opens up possibilities for using technical measurements to provide valid exposure assessments and intervention evaluations of kneeling and squatting, as well as increased feasibility for technical measurements in large cohort studies. Practitioner summary: Quantification of kneeling and squatting during work is important for prevention, but limited by either imprecise or costly methods. This study developed and validated an inexpensive wireless accelerometer-based measurement method that can be used by practitioners and researchers for long-term measurements of kneeling and squatting during free-living working conditions.