Global reductions in manual agricultural work capacity due to climate change.

Manual outdoor work is essential in many agricultural systems. Climate change will make such work more stressful in many regions due to heat exposure. The physical work capacity metric (PWC) is a physiologically based approach that estimates an individual's work capacity relative to an environment without any heat stress. We computed PWC under recent past and potential future climate conditions. Daily values were computed from five earth system models for three emission scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5) and three time periods: 1991-2010 (recent past), 2041-2060 (mid-century) and 2081-2100 (end-century). Average daily PWC values were aggregated for the entire year, the growing season, and the warmest 90-day period of the year. Under recent past climate conditions, the growing season PWC was below 0.86 (86% of full work capacity) on half the current global cropland. With end-century/SSP5-8.5 thermal conditions this value was reduced to 0.7, with most affected crop-growing regions in Southeast and South Asia, West and Central Africa, and northern South America. Average growing season PWC could falls below 0.4 in some important food production regions such as the Indo-Gangetic plains in Pakistan and India. End-century PWC reductions were substantially greater than mid-century reductions. This paper assesses two potential adaptions-reducing direct solar radiation impacts with shade or working at night and reducing the need for hard physical labor with increased mechanization. Removing the effect of direct solar radiation impacts improved PWC values by 0.05 to 0.10 in the hottest periods and regions. Adding mechanization to increase horsepower (HP) per hectare to levels similar to those in some higher income countries would require a 22% increase in global HP availability with Sub-Saharan Africa needing the most. There may be scope for shifting to less labor-intensive crops or those with labor peaks in cooler periods or shift work to early morning.

Tip of the iceberg: unveiling the impact on back disorders from cumulative physical job exposure and evaluating bias from the healthy worker effect using a nationwide longitudinal cohort study.

PURPOSE: Longitudinal studies across various sectors with physically demanding jobs are notably absent in back disorder risk research. This study aimed to investigate the relationship between cumulative physical job exposure (PJE) and hospital-diagnosed back disorders among individuals in Denmark. To assess the healthy worker effect, we compared the cumulative risk estimate with results from a naive cross-sectional model ignoring PJE history. METHODS: A nationwide longitudinal cohort study was conducted using Danish registers, encompassing individuals born between 1975 and 1978 and working in 1996. Cumulative PJE was measured with a 10-year look-back period for each year 2006-2017. PJE consisted of lower-body occupational exposures, including the total weight lifted, stand/sit ratio, and the frequency of lifting more than 20 kg per day from a job exposure matrix. Odds ratio for back disorders was estimated for each year and all years combined. RESULTS: The results unveiled a significant 31% increase in the risk of hospital-diagnosed back disorders after 4 years of cumulative PJE. The lowest risk (7%) was observed for incident back disorders with 1 year of exposure, suggesting a healthy worker effect. Nevertheless, this risk is still significantly elevated. This cumulative estimate is fourfold the estimate from the 2006 naive cross section model. CONCLUSION: Our study clearly demonstrates an 31% increase in the risk of hospital-diagnosed back disorders with just 4 years of PJE over a 10-year period. Further, we find that cross-sectional studies strongly underestimate the risk of back disorders due to the healthy worker effect.

Occupational tasks associated with shoulder pain and upper extremity disability: a cross-sectional study in the Johnston County Osteoarthritis Project.

BACKGROUND: Shoulder pain is a leading cause of disability. Occupations requiring high upper extremity demands may put workers at greater risk of shoulder injury and resulting pain. We examined associations of occupation with shoulder pain and upper extremity disability in the Johnston County Osteoarthritis Project. METHODS: Work industry and occupational tasks for the longest job held were collected from participants. At follow-up ranging from 4-10 years later, participants were asked about shoulder symptoms (pain, aching, or stiffness occurring most days of 1 month in the last year) and given a 9-item, modified Disabilities Arm Shoulder and Hand (DASH) questionnaire to categorize disability from 0-4 (none-worst). Logistic regression and cumulative logit regression models were used to estimate associations with prevalent shoulder symptoms and with worse disability category, respectively. Models were adjusted for cohort, age, sex, race, education and time to follow-up. Sex- and race-stratified associations were evaluated. RESULTS: Among 1560 included participants, mean age was 62 years (standard deviation ± 9 years); 32% were men, and 31% were Black. Compared to the managerial/professional industry, higher odds of both shoulder symptoms and worse upper extremity disability were seen for most industrial groups with physically demanding jobs, particularly the service industry. Work that often or always required lifting/moving > 10 lbs. was associated with higher odds of shoulder symptoms. Work that sometimes or always required heavy work while standing was associated with higher odds of shoulder symptoms, and this association was stronger among men and White workers. CONCLUSION: Physically demanding occupations were associated with increased occurrence of shoulder pain and disability. Mitigating specific physical work demands may reduce shoulder-related disability.

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.

Sustainability of physical work capacity two years post outpatient cardiac rehabilitation.

OBJECTIVE: To determine if supervised training, after the completion of cardiac rehabilitation program, performed for a further two years would help maintain beneficial effects achieved during prolonged outpatient cardiac rehabilitation. DESIGN: Longitudinal parallel-grouped intervention study. SUBJECTS: Patients with coronary artery disease (n = 41, age 59.5 ± 9.3 years), who finished cardiac rehabilitation phase III in our outpatient cardiac rehabilitation facility. INTERVENTION: Two years of supervised exercise training consisting of endurance (either high intensity interval training or pyramid training) and resistance training sessions once a week. MAIN MEASUREMENT: Peak physical work capacity was assessed via an ergometry testing at the beginning and at the end of the study. RESULTS: Comparisons between end-of-cardiac rehabilitation and two years post cardiac rehabilitation revealed maintenance of peak physical work capacity after two years (begin vs end: 170 ± 59 W vs 167 ± 60 W; -0.5 ± 12.8%; p = 0.521). This was independent of exercise training protocols (percent change begin vs end: pyramid: 1.5 ± 11.8%; interval: -1.6 ± 13.4%; p = 0.459). CONCLUSION: Improvement of physical exercise capacity gained during outpatient cardiac rehabilitation can be maintained for up to two years by once-weekly supervised exercise training. Long-term, group-based exercise programs offered at the end of cardiac rehabilitation might be an effective tool to help patients maintain their physical work capacity.

Return to sports and physical work after anatomical and reverse shoulder arthroplasty.

BACKGROUND: No consensus has been reached on the return to sports or physical work after shoulder arthroplasty due to a shortage of literature. The purpose of this study was to investigate return to sports or physical work after anatomical total shoulder arthroplasty (aTSA) and reverse shoulder arthroplasty (RSA), as well as the clinical and radiographic outcomes. METHODS: The inclusion criteria were as follows: 1) aTSA or RSA between 2012 and 2017, and 2) patients who preoperatively participated in sports or physical work. The exclusion criteria were as follows: 1) revision arthroplasty, 2) fracture/dislocation, 3) fracture sequelae, 4) postinfection, and 5) <2-year follow-up. Sports and physical work were classified as low-, medium-, or high-load activities. Range of motion, Constant score, sport or work return, and radiographic findings were evaluated and compared between aTSA and RSA groups. RESULTS: The subjects who met the criteria were 90 shoulders in 86 patients. The aTSA group consisted of 30 shoulders (10 men and 20 women) with a mean age of 71 ± 8 years (range, 56-85). The RSA group consisted of 60 shoulders (39 men and 21 women) with a mean age of 72 ± 6 years (range, 56-83). Active range of motion significantly improved after surgery in all directions in the aTSA group but only in flexion and external rotation in the RSA group. Postoperative external and internal rotations, as well as postoperative Constant scores and satisfaction, were significantly better in the aTSA than in the RSA group. In the aTSA group, the return rate was 93%, and the complete return rate was 70%. In the RSA group, the return rate was 83%, and the complete return rate was 30%. The complete return rate was significantly higher in the aTSA than in the RSA group. Only one aTSA shoulder showed loosening of the glenoid implant, and 8 RSA shoulders demonstrated low-grade scapular notching. CONCLUSION: The return to sports or physical work rates after aTSA and RSA were high; however, the complete return rates were significantly higher in the aTSA group than in the RSA group. No radiographic failures were identified except for one asymptomatic glenoid loosening with a midterm follow-up.

Comparison Between Musculoskeletal Pain and Gender-Specific, Non-gendered Job-Exposure Matrix and Self-reported Exposures in CONSTANCES.

PURPOSE: Musculoskeletal disorders (MSDs) are common worldwide and gender differences exist in terms of prevalence and disability. MSDs are a leading cause of sick leave and physical work exposures. To assess the association between physical exposures assessed by the gender-specific CONSTANCES Job-Exposure Matrix (JEM) and musculoskeletal pain in six areas: neck pain, shoulder pain, elbow/arm pain, hand/wrist pain, low back pain, knee/leg pain; and to compare the results with those obtained using the non-gendered CONSTANCES JEM and with individual self-report exposures. METHODS: We included 48,736 male and 63,326 female workers from the CONSTANCES cohort (France). The association between 27 physical exposures and musculoskeletal self-reported pain in six body areas was assessed using logistic regression. We conducted the analysis with three types of exposures: (1) individual self-reported exposures; (2) gender-specific CONSTANCES JEM; (3) non-gendered CONSTANCES JEM, and adjusted for age and Body Mass Index (BMI). Analyses were stratified by gender. RESULTS: The associations to the gender-specific and non-gendered JEM were similar. The odds ratios using individual self-reported exposures were comparable to the JEM-based associations, with the exceptions of the exposures 'change tasks', 'rest eyes' and 'reach behind'. In some comparisons, there were differences in the direction and/or significance of effects between genders (regardless of whether the JEM used was gender-specific or not). CONCLUSION: The gender-specific and non-gendered JEMs gave similar results, hence, developing physical work exposures JEMs that are gender-specific may not be essential. However, when predicting musculoskeletal pain, it seems relevant to stratify the analysis by gender.

Associations between physical work environment, workplace support for health, and presenteeism: a COVID-19 context.

OBJECTIVE: Presenteeism has, in a larger sense, been viewed as a negative behaviour, although a limited body of studies suggests and reports its positive implications in an organizational context. This study assessed the association between the physical work environment (PWE) and presenteeism as well as the moderating influence of workplace support for health (WSH) on this relationship. METHODS: This study adopted the cross-sectional design alongside a sensitivity analysis and techniques against common methods bias. The study population was employees of private and public organizations in Accra, Ghana. A total of 590 employees participated in the study and hierarchical linear regression was used to present the results. RESULTS: PWE had a positive relationship with presenteeism (ß = 0.15; t = 3.04; p < 0.05), which means that higher presenteeism was associated with larger PWE scores. WSH positively moderated the relationship between PWE and presenteeism (ß = 0.23; t = 4.84; p < 0.001). CONCLUSIONS: Organizations with more satisfactory work environments may serve as preferred protective places for employees during a pandemic, more so within organizations with higher WSH. Interventions rolled out to improve PWE and to provide WSH can attenuate the potential negative influences of presenteeism on individual health and organizational productivity.

Do patient characteristics affect the predictive validity of Functional Capacity Evaluations?

PURPOSE: The aim of this study was to identify patient-related characteristics that affect the predictive validity of the FCE assessment ELA. METHODS: A prospective multicenter study was conducted on 303 patients with musculoskeletal disorders (MSD) recruited from eleven rehabilitation centers. The ELA-based estimation of the participants' ability to cope with physical work demands was considered valid if RTW was paired with a positive ELA outcome (≥ moderate) as well as if non-RTW was accompanied by a negative ELA outcome (rather or very poor). In the remaining cases, the ELA result was judged as non-valid. To reduce the risk of false conclusions, the rating was performed inversely in participants that (1) reported severe limitations regarding their productivity at work, (2) attributed RTW to a change in job resp. a reduction of their physical work demands and in those that (3) attributed non-RTW to non-physical reintegration barriers only. Using questionnaires, 28 patient-related characteristics were collected. Logistic regression models were calculated to identify characteristics that affected the predictive validity of ELA. RESULTS: ELA was considered valid in 208 of 303 (69%) participants. A moderate and strong pain-related disability at work were associated with a 0.15-fold (95% confidence interval (95% CI) 0.05-0.46), respectively, 0.19-fold (95% CI 0.05-0.72) chance for a valid outcome. In addition, a negative influence was found in participants that reported psychosocial distress (odds ratio (OR) 0.35; 95% CI 0.15-0.82), a native language different from the national language (OR 0.16; 95% CI 0.05-0.56) as well as in those that expected to return to work, but not within one month (OR 0.17; 95% CI 0.06-0.46). Further variables-including age, employment status, fear-avoidance beliefs and the level of physical work demands-did not affect the predictive validity of ELA. CONCLUSIONS: The results suggest that the predictive validity of ELA is primarily limited by patients that report a moderate or strong pain-related disability at work, psychosocial distress as well as the expectation to return to work, but not within one month. Furthermore, a negative influence can be assumed for language barriers.

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.

Matching Perceived Physical Capacity and Work Demands: A New Classification of the Modified Spinal Function Sort (M-SFS).

Purpose The aims of this study were (1) to develop a new classification for the scores of the Modified Spinal Function Sort (M-SFS) which is related to the level of physical work demands and (2) to test the predictive value of the M-SFS classification. Methods The classification was carried out in 194 subjects with musculoskeletal disorders (MSD) attending a work-related medical rehabilitation from four rehabilitation centers. External criterion was a Functional Capacity Evaluation (FCE)-based work capacity estimation according to the classification used in Germany ("REFA") which differentiates between light, light to medium, medium and heavy work. The optimal cut-offs for the M-SFS were allocated using the Youden index. Logistic regression models were calculated based on 147 subjects who participated in the follow-up survey to evaluate the predictive validity of the M-SFS classification with regard to sustainable return to work (RTW; employment at the 3-month follow-up combined with a low level of sick leave). Results Cut-offs for M-SFS scores were 44 (light work), 54 (light to medium work), 62 (medium work) and 73 (heavy work). A match between the M-SFS category and the level of physical work demands was associated with a more than threefold higher RTW chance compared to subjects with a negative discrepancy. In case the M-SFS category was above the physical demand level the RTW-chance was more than 13-fold higher. Conclusions M-SFS scores can be classified into four levels of physical work demands. If the perceived work capacity matches or exceeds the level of physical work demands patients with MSD have a substantially higher probability to return to work after rehabilitation. More studies are needed to confirm or reject our findings and overcome some of the weaknesses of this study.

Psychosocial Working Conditions Play an Important Role in the Return-to-Work Process After Total Knee and Hip Arthroplasty.

Purpose Both personal and work-related factors affect return to work (RTW) after total knee arthroplasty (TKA) and total hip arthroplasty (THA). Little is known about work-related factors associated with the recovery process. This study aimed to determine which work-related factors are associated with time to RTW for both TKA and THA patients. Methods A prospective multicenter survey study was conducted that included patients aged 18-63, had a paid job and were scheduled to undergo primary TKA/THA. Surveys were completed preoperatively, 6 weeks, and 3, 6, and 12 months postoperatively, and included four domains of work-related factors: work characteristics, physical working conditions, psychosocial working conditions and work adjustments. Control variables included age, sex, education, and comorbidity. Time to RTW was defined as days from surgery until RTW. Multivariate linear regression analyses were conducted separately for TKA/THA patients. Results Enrolled were 246 patients (n = 146 TKA, n = 100 THA, median age 56 years, 57% female). Median time to RTW was 79 days (IQR 52.0-146.0). Mainly physical tasks (TKA: B 58.2, 95%CI 9.5-106.8; THA: B 52.1, 95%CI 14.1-90.2) and a combination of physical and mental tasks (TKA: B 50.2, 95%CI 6.4-94.0; THA B 54.0, 95%CI 24.2-83.7) were associated with longer time to RTW after both TKA and THA. More possibilities for personal job development (B - 12.8, 95%CI - 25.3-0.4) and more work recognition (B - 13.2, 95%CI - 25.5 to - 0.9) were significantly associated with shorter time to RTW after TKA. Higher quality of supervisor leadership (B - 14.1, 95%CI - 22.2 to - 6.0) was significantly associated with shorter time to RTW after THA. Conclusion The findings of this study stress the importance of psychosocial working conditions, besides type of job tasks, in RTW after TKA/THA. Further research on work-related factors is needed, as arthroplasty is being performed on an increasingly younger population of knee and hip OA patients for whom participating in work is of critical importance.

Wearable Sensors and Machine Learning for Hypovolemia Problems in Occupational, Military and Sports Medicine: Physiological Basis, Hardware and Algorithms.

Hypovolemia is a physiological state of reduced blood volume that can exist as either (1) absolute hypovolemia because of a lower circulating blood (plasma) volume for a given vascular space (dehydration, hemorrhage) or (2) relative hypovolemia resulting from an expanded vascular space (vasodilation) for a given circulating blood volume (e.g., heat stress, hypoxia, sepsis). This paper examines the physiology of hypovolemia and its association with health and performance problems common to occupational, military and sports medicine. We discuss the maturation of individual-specific compensatory reserve or decompensation measures for future wearable sensor systems to effectively manage these hypovolemia problems. The paper then presents areas of future work to allow such technologies to translate from lab settings to use as decision aids for managing hypovolemia. We envision a future that incorporates elements of the compensatory reserve measure with advances in sensing technology and multiple modalities of cardiovascular sensing, additional contextual measures, and advanced noise reduction algorithms into a fully wearable system, creating a robust and physiologically sound approach to manage physical work, fatigue, safety and health issues associated with hypovolemia for workers, warfighters and athletes in austere conditions.

Characterizing the Effects of Explosive Ordnance Disposal Operations on the Human Body While Wearing Heavy Personal Protective Equipment.

OBJECTIVE: To provide a comprehensive characterization of explosive ordnance disposal (EOD) personal protective equipment (PPE) by evaluating its effects on the human body, specifically the poses, tasks, and conditions under which EOD operations are performed. BACKGROUND: EOD PPE is designed to protect technicians from a blast. The required features of protection make EOD PPE heavy, bulky, poorly ventilated, and difficult to maneuver in. It is not clear how the EOD PPE wearer physiologically adapts to maintain physical and cognitive performance during EOD operations. METHOD: Fourteen participants performed EOD operations including mobility and inspection tasks with and without EOD PPE. Physiological measurement and kinematic data recording were used to record human physiological responses and performance. RESULTS: All physiological measures were significantly higher during the mobility and the inspection tasks when EOD PPE was worn. Participants spent significantly more time to complete the mobility tasks, whereas mixed results were found in the inspection tasks. Higher back muscle activations were seen in participants who performed object manipulation while wearing EOD PPE. CONCLUSION: EOD operations while wearing EOD PPE pose significant physical stress on the human body. The wearer's mobility is impacted by EOD PPE, resulting in decreased speed and higher muscle activations. APPLICATION: The testing and evaluation methodology in this study can be used to benchmark future EOD PPE designs. Identifying hazards posed by EOD PPE lays the groundwork for developing mitigation plans, such as exoskeletons, to reduce physical and cognitive stress caused by EOD PPE on the wearers without compromising their operational performance.

Exploring Localized Muscle Fatigue Responses at Current Upper-Extremity Ergonomics Threshold Limit Values.

OBJECTIVE: The purpose of this study was to evaluate localized muscle fatigue responses at three upper-extremity ergonomics threshold limit value (TLV) duty cycles. BACKGROUND: Recently, a TLV equation was published to help mitigate excessive development of localized muscle fatigue in repetitive upper limb tasks. This equation predicts acceptable levels of maximal voluntary contraction (% MVC) for a given duty cycle (DC). Experimental validation of this TLV curve has not yet been reported, which can help guide utilization by practitioners. METHOD: Eighteen participants performed intermittent isometric elbow flexion efforts, in three separate counter-balanced sessions, at workloads defined by the American Conference of Governmental Industrial Hygenists' (ACGIH) TLV equation: low DC (20% DC, 29.6% MVC), medium DC (40% DC, 19.7% MVC), and high DC (60% DC, 13.9% MVC). Targeted localized muscle fatigue (LMF) of the biceps brachii was tracked across numerous response variables, including decline in strength (MVC), electromyography (EMG) amplitude and mean power frequency (MnPF), and several psychophysical ratings. RESULTS: At task completion, biceps MnPF and MVC (strength) were significantly different between each TLV workload, with the high DC condition eliciting the largest declines in MnPF and MVC. CONCLUSION: Findings demonstrate that working at different DCs along the ACGIH TLV curve may not be equivalent in preventing excessive LMF. Higher DC workloads elicited a greater LMF response across several response variables. APPLICATION: High DC work of the upper extremity should be avoided to mitigate excess LMF development. Current TLVs for repetitive upper-extremity work may overestimate acceptable relative contraction thresholds, particularly at higher duty cycles.

Oxygen Consumption and Blood Pressure Are Not Influenced by Use of a Backpack Hip Strap.

INTRODUCTION: Several studies have explored the effect of backpack carriage on physiologic responses while walking, but few have focused specifically on the influence of the use of a hip strap on these responses. The aim of this study was to investigate the effect of a backpack hip strap on physiologic responses when walking at a moderate intensity while carrying a backpack with a standardized relative load of 30% of the wearer's body mass. METHODS: Twenty-three healthy, active participants carrying backpacks walked on a treadmill at a speed and grade that elicited 40-50% of their heart rate reserve. Participants completed 2 counterbalanced 30-min trials, one with the hip strap in the strapped condition and one with the hip strap unfastened. Metabolic, heart rate, blood pressure, and muscle oxygen saturation (SmO2) responses were recorded during both trials. For each variable, 5-min intervals were averaged at baseline, 5, 10, 15, 20, 25, and 30 min. A repeated measures ANOVA test was used to evaluate the differences between the conditions at each time point. Data reported are the values from the final 5-min interval (30 min) and are reported as mean±SD. RESULTS: No differences were found between strapped and unstrapped trials for oxygen consumption (strapped 21.9±4.2 mL·kg-1·min-1; unstrapped 22.0±4.4 mL·kg-1·min-1, P=0.842), Δmean arterial pressure (strapped +5±17 Δmm Hg; unstrapped +12±14 Δmm Hg, P=0.128) or muscle oxygen saturation of the quadriceps (strapped 86±15%; unstrapped 90±12%, P=0.359) and calf (strapped 73±19%; unstrapped 81±12%, P=0.888). CONCLUSIONS: These results suggest that wearing a hip strap does not influence physiologic responses up to 30 min of moderate intensity walking while carrying 30% of the wearer's mass.

Determinants of heat stress and strain in electrical utilities workers across North America as assessed by means of an exploratory questionnaire.

Previous field studies monitoring small groups of participants showed that heat stress in the electrical utilities industry may be detrimental to worker health and safety. Our aim in this study was to characterize heat stress and strain in electrical utilities workers across North America. A total of 428 workers in the power generation, transmission, and distribution industry across 16 U.S. states and 3 Canadian Provinces completed a two-part on-line questionnaire anonymously. The first part comprised 13 general questions on the employee's workplace location, role in the organization, years of experience, general duties, average work shift duration, and other job-related information. It also included two questions on self-reported heat stress. The second part consisted of the "Heat Strain Score Index" (HSSI), a validated questionnaire which evaluates heat stress at the workplace as "safe level" (score ≤13.5: worker experiences no/low heat strain), "caution level" (score 13.6 to 18.0: moderate risk for heat strain), and "danger level" (score >18.0: high risk for heat strain). In addition to the survey, we obtained meteorological data from weather stations in proximity (12.3 ± 12.2 km) to the work locations. Based on the HSSI, 32.9%, 22.3%, and 44.4% of the responders' workplaces were diagnosed as "safe level," "caution level," and "danger level," respectively. The HSSI varied significantly depending on the occupation from 4.9 ± 3.2 in contact center workforce to 19.1 ± 5.4 in mechanics (p < 0.001), and demonstrated moderate linear relationships with summertime (June, July, August) midday air temperature (r = 0.317, p < 0.001) and outdoor midday Wet-Bulb Globe Temperature (r = 0.322, p < 0.001). The highest HSSI was observed in mechanics, machine operators in line installations, line workers, electricians, and meter-readers. We conclude that electrical utilities workers experience instances of severe environmental heat stress resulting in elevated levels of heat strain, particularly when performing physically demanding tasks (e.g., manually climbing utility poles, installing lines).

Associations between physical and psychosocial work environment factors and sickness absence incidence depend on the lengths of the sickness absence episodes: a prospective study of 27 678 Danish employees.

OBJECTIVES: This study examined if the association between work environment factors and sickness absence (SA) depended on the inclusion or exclusion of short-term SA episodes. METHODS: We linked the 'Work Environment and Health in Denmark' survey with the 'Danish Register of Work Absences' (n=27 678). Using covariate adjusted Cox regression, we examined the associations between work environment factors and SA by changing the cut-off points for the length of the SA episodes, for example, episodes ≥1 day, ≥6 days and ≥21 days. We examined three physical work environment factors: 'Back bend or twisted', 'Lifting or carrying', 'Wet hands' and three psychosocial work environment factors: 'Poor influence', 'Role conflicts' and 'Bullying'. RESULTS: 'Back bend or twisted' and 'Lifting or carrying' had small significant HRs for SA episodes ≥1 day and large and highly significant HRs for SA episodes ≥6 days and ≥21 days. 'Wet hands' had small significant HRs for SA episodes ≥1 day for both sexes and large and highly significant HR for ≥6 days for women. HRs of all three psychosocial factors were highly significant for SA episodes ≥1 day and ≥6 days for both sexes, and 'Poor influence' and 'Role conflicts' were significant for SA episodes ≥21 days for women. CONCLUSIONS: The physical work factors had higher associations with SA when SA episodes of 1-5 days were excluded and focus was on SA episodes ≥6 days. The psychosocial work factors were strongly associated with SA both with and without SA episodes of 1-5 days included in the analyses.

Lower limb venous and arterial peripheral diseases and work conditions: systematic review.

OBJECTIVES: The individual peripheral vascular disease risk factors are well documented, but the role of work conditions remains equivocal. This systematic review aims to assess relationships between lower limb peripheral venous diseases (lower limb varicose veins (LLVV), venous thromboembolism (VTE) comprising deep vein thrombosis and pulmonary embolism), peripheral arterial disease (intermittent claudication, aortic dissection, aortic aneurysm) and occupational constraints among working adults. METHODS: Several databases were systematically searched until February 2019 for observational studies and clinical trials. Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was used for article selection. Quality assessment and risk of bias were evaluated using Strengthening the Reporting of Observational Studies in Epidemiology and Newcastle-Ottawa scales. RESULTS: Among the 720 screened articles, 37 remained after full-text evaluation. Among the 21 studies on LLVV, prolonged standing was significantly associated to a higher risk of varicose veins with a threshold probably around >3 to 4 hours/day but exposure duration in years was not sufficiently considered. Seated immobility was often observed in workers, with no sufficient evidence to prove that prolonged sitting at work is related to VTE. Carrying heavy loads, stress at work and exposure to high temperatures have emerged more recently notably in relation to varicose veins but need to be better explored. Only three studies discussed the potential role of work on peripheral arterial disease development. CONCLUSIONS: Although some observational studies showed that prolonged standing can be related to varicose veins and that seated immobility at work could be linked to VTE, very little is known about peripheral arterial disease and occupational constraints. Clinical trials to determine preventive strategies at work are needed. PROSPERO REGISTRATION NUMBER: CRD42019127652.

Occupational physical activity and cardiovascular disease in the United States.

BACKGROUND: Emerging evidence, predominately from European and Asian countries, describes opposing effects of occupational physical activity (OPA) and leisure-time physical activity (LTPA) on cardiovascular health. This analysis examined cardiovascular disease (CVD) prevalence associated with OPA and LTPA. METHODS: This cross-sectional analysis of 2015 National Health Interview Survey data (n=16 974) employed logistic regression to estimate odds (OR) of self-reported CVD (coronary heart disease, heart attack, stroke or angina) with self-reported total occupational activity (TOA), occupational exertion (OE), occupational standing and walking (OSW) and LTPA. OPA was measured using two questions: 'How often does your job involve…' (1) 'repeated lifting, pushing, pulling or bending?' (OE) and (2) 'standing or walking around?' (OSW) with responses on a 5-item Likert scale (0=never, 4=always). TOA was categorised similarly after summing OE and OSW scores. LTPA was defined as 0, 1-149 or ≥150 min/week of moderate-to-vigorous activity. All models adjusted for common socioeconomic variables and additional analyses were stratified by sex, smoking status and LTPA. RESULTS: Odds for CVD were higher when 'always' performing TOA (OR 1.99 95% CI 1.12 to 3.53), OE (OR 2.15, 95% CI 1.45 to 3.19) or OSW (OR 1.84, 95% CI 1.07 to 3.17) compared with 'never'. When restricting to never-smokers, odds for CVD were higher when 'always' performing TOA (OR 3.00, 95% CI 1.38 to 6.51) and OE (OR 3.00, 95% CI 1.80 to 5.02) versus 'never'. CONCLUSION: Associations of high OPA with CVD were equally apparent across sexes, stronger in lower LTPA levels and stronger in never-smokers. While uncontrolled confounding is still possible, even after extensive adjustment, the seemingly paradoxical adverse associations with OPA and CVD should be investigated further.