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Abstract Ever‐increasing bandwidth requirements from various industries drive the need for the ever‐increasing bandwidth of antennas used for testing. Broadband Double‐Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state‐of‐the‐art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial‐to‐ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber‐filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented.

Abstract Broadband double‐ridged guide horn (DRGH) antennas are extensively used in antenna measurement and electromagnetic compatibility and interference testing, especially the 1–18 GHz DRGH antenna which is widely accepted as a standard for this band. Certain deficiencies in the radiation patterns have been identified and corrected by several authors, but the use was still limited to the 1–18 GHz frequency band. The incorporation of absorber materials and lenses has resulted in horn antennas with wider bandwidths; however, this complicates the manufacturing process and restricts these designs to lower power applications. Simulated and measured results for a new 0.5–18 GHz (36:1) DRGH antenna are presented here. The wider bandwidth is made possible by a new cavity design and optimising the design of the other antenna sections to allow wideband operation without using a lens or absorber. The new design has double the bandwidth ratio and is very compact, with an aperture size of 26.4 cm × 15.2 cm; the aperture sides are less than 12% larger than the sides of the aperture of the conventional 1–18 GHz DRGH antenna (24.2 cm × 13.6 cm).

Background: Emerging epidemiological evidence suggests that compared to engaging in 1 activity mode alone, a combination of moderate-to-vigorous physical activity (MVPA: brisk walking/jogging, cycling) and muscle-strengthening exercise (MSE: push-ups/sit-ups, using weight machines) has more favorable associations with optimal weight status. However, few studies have examined the dose-dependent and joint associations of MVPA and MSE with obesity., Methods: Based on cross-sectional analyses of the European Health Interview Survey Wave 2 (2013-2014), we examined prevalence ratios (PRs) of joint and stratified associations between MVPA (4 categories: (i) 0 min/week, (ii) 1-149 min/week, (iii) 150-299 min/week, and (iv) ≥300 min/week) and MSE (3 categories: (i) 0 day/week, (ii) 1 day/week, and (iii) ≥2 days/week) with body mass index-defined obesity (body mass index of ≥30.0 kg/m 2 ) using Poisson regression with robust error variance. PRs were examined unadjusted and adjusted for sociodemographic and lifestyle characteristics (e.g., sex, age, education, income, and smoking status)., Results: Data were available for 280,456 adults (≥18 years), of which 46,166 (15.5%) were obese. The interaction MVPA × MSE guideline adherence was statistically significant for obesity (p ≤ 0.05). The joint MVPA-MSE analysis showed that compared to the reference group (i.e., no MVPA and no MSE), the PRs followed a dose-dependent pattern, with the lowest observed among those reporting ≥150 MVPA min/week and ≥1 MSE days/week (PR: 0.43; 95% confidence interval: 0.41-0.46). When stratified across each MVPA strata, the PRs were mostly lower among those engaging in MSE 1 day/week, as compared to those doing MSE ≥2 days/week., Conclusion: There was evidence for a dose-dependent association between joint MVPA-MSE with a reduced prevalence of obesity. Public health strategies for the prevention and management of obesity should recommend both MVPA and MSE., Competing Interests: Competing interests The authors declare that they have no competing interests., (Copyright © 2021. Production and hosting by Elsevier B.V.)

Abstract: The Physical Activity Guidelines recommend performing 150 min of moderate- to vigorous-intensity aerobic physical activity (MVPA) per week. These guidelines also recommend muscle-strengthening physical activity (MSPA) on ≥2 d·wk-1 for additional benefits including muscular fitness and bone health. The majority of the scientific evidence supporting the PA recommendations for health comes from studies of MVPA while the possible contributions of MSPA in these findings have been overlooked historically. Emerging evidence suggests that MSPA can independently protect against major cardiometabolic risk factors, chronic diseases, and mortality. Additional data from clinical trials indicate that many of the well-known health benefits of exercise, like improvements in cardiovascular disease risk factors, are more robust with combined MVPA and MSPA. This review will clarify the relative benefits of MSPA versus MVPA on health-related outcomes to determine the best type of PA for health., (Copyright © 2022 by the American College of Sports Medicine.)

Background: Automated wearable cameras present a new opportunity to accurately assess human behavior. However, this technology is seldom used in the study of adolescent's screen exposure, and the field is reliant on poor-quality self-report data., Objective: This study aimed to examine adolescents' screen exposure by categorizing the type and context of behaviors using automated wearable cameras., Methods: Adolescents (mean age 15.4 years, SD 1.6 years; n=10) wore a camera for 3 school evenings and 1 weekend day. The camera captured an image every 10 seconds. Fieldwork was completed between February and March 2020, and data were analyzed in August 2020. Images were date and time stamped, and coded for screen type, content, and context., Results: Data representing 71,396 images were analyzed. Overall, 74.0% (52,842/71,396) of images contained screens and 16.8% (11,976/71,396) of images contained multiple screens. Most screen exposures involved television sets (25,950/71,396, 36.3%), smartphones (20,851/71,396, 29.2%), and laptop computers (15,309/71,396, 21.4%). The context of screen use differed by device type, although most screen exposures occurred at home (62,455/64,856, 96.3%) and with solitary engagement (54,430/64,856, 83.9%). The immediate after-school period saw high laptop computer use (4785/15,950, 30.0%), while smartphone use (2059/5320, 38.7%) peaked during prebedtime hours. Weekend screen exposure was high, with smartphone use (1070/1927, 55.5%) peaking in the early morning period and fluctuating throughout the day., Conclusions: There was evidence for high screen use during the after-school and weekend period, mostly through solitary engagement, and within the home environment. The findings may inform the basis of larger studies aimed at examining screen exposure in free-living conditions., (©George Thomas, Jason A Bennie, Katrien De Cocker, Fitria Dwi Andriyani, Bridget Booker, Stuart J H Biddle. Originally published in JMIR Pediatrics and Parenting (https://pediatrics.jmir.org), 21.03.2022.)

Background: Obesity is a significant and growing public health problem in high-income countries. Little is known about the relationship between resistance exercise (RE), alone and in combination with aerobic exercise (AE), and the risk of developing obesity. The purpose of this prospective cohort study was to examine the associations between different amounts and frequencies of RE, independent of AE, and incident obesity., Methods and Findings: Participants were 11,938 healthy adults ages 18-89 years with a BMI < 30 kg/m2 at baseline who completed at least 2 clinical examinations during 1987-2005 as part of the Aerobics Center Longitudinal Study. Self-reported RE participation in minutes/week and days/week was collected from a standardized questionnaire. Incident obesity was defined as a BMI ≥ 30 kg/m2 at follow-up. Incident obesity was also defined by waist circumference (WC) > 102/88 cm for men/women and percent body fat (PBF) ≥ 25%/30% for men/women at follow-up in participants who were not obese by WC (n = 9,490) or PBF (n = 8,733) at baseline. During the average 6-year follow-up, 874 (7%), 726 (8%), and 1,683 (19%) developed obesity defined by BMI, WC, or PBF, respectively. Compared with no RE, 60-119 min/wk of RE was associated with 30%, 41%, and 31% reduced risk of obesity defined by BMI (hazard ratio [95% CI], 0.70 [0.54-0.92], p = 0.008), WC (0.59 [0.44-0.81], p < 0.001), and PBF (0.69 [0.57-0.83], p < 0.001), respectively, after adjusting for confounders including age, sex, examination year, smoking status, heavy alcohol consumption, hypertension, hypercholesterolemia, diabetes, and AE. Compared with not meeting the RE guidelines of ≥2 d/wk, meeting the RE guidelines was associated with 18%, 30%, and 30% reduced risk of obesity defined by BMI (hazard ratio [95% CI], 0.82 [0.69-0.97], p = 0.02), WC (0.70 [0.57-0.85], p < 0.001), and PBF (0.70 [0.62-0.79], p < 0.001), respectively. Compared with meeting neither guideline, meeting both the AE and RE guidelines was associated with the smallest hazard ratios for obesity. Limitations of this study include limited generalizability as participants were predominantly white men from middle to upper socioeconomic strata, use of self-reported RE, and lack of detailed diet data for the majority of participants., Conclusions: In this study, we observed that RE was associated with a significantly reduced risk of obesity even after considering AE. However, meeting both the RE and AE guidelines was associated with the lowest risk of obesity., Competing Interests: The authors have declared that no competing interests exist.

Background: There is increasing interest in the association between psychological distress and time spent in sedentary behaviour (e.g. sitting), a highly prevalent behaviour in modern society. The limited evidence is mixed and mainly based on studies using self-reported sedentary time. Few studies have investigated device-based total sedentary time in its association with distress. None, however, have examined device-based domain-specific sedentary time in relation to psychological distress. The aim of this study was to investigate whether device-based total and domain-specific sedentary behaviour were associated with psychological distress., Methods: Flemish employees (n = 401; 20-64 years; 42.6% male; 83.6% had a 'physically active occupation') of seven organizations in service and production sectors participated. Sedentary behaviour (exposure) was assessed by two Axivity AX3 accelerometers (one placed on the thigh and one placed between the shoulders) for two to four consecutive working days. Based on diary completion, domain-specific sedentary behaviour (leisure vs. work) was assessed. The 12-item General Health Questionnaire was used to assess psychological distress (outcome). Adjusted hierarchical multiple regression models were conducted to report on the associations between total and domain-specific sedentary behaviour and psychological distress., Results: About 35% of the sample had high levels of distress and average total sedentary time was 7.2 h/day. Device-based total sedentary behaviour [B = -0.009, 95% confidence interval (CI), -0.087 to 0.068], leisure-time (B = 0.001, 95% CI, -0.017 to 0.018) and work-related (B = 0.004, 95% CI, -0.006 to 0.015) sedentary behaviour were not significantly associated with psychological distress., Conclusion: This cross-sectional study examining the association between device-based total and domain-specific sedentary behaviour and psychological distress among employees showed a lack of significant findings., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.)

Regular physical activity is a key modifiable non-pharmacological treatment to enhance sleep quality, a key predictor of optimal health and wellbeing. Most of the evidence on physical activity and sleep quality is based on studies assessing the effects of aerobic moderate-to-vigorous physical activity (e.g. brisk walking, cycling, jogging). Emerging clinical evidence suggests that muscle-strengthening exercise (e.g. push-ups, using weight machines) may also be beneficial for sleep quality. However, since no studies have examined the associations between muscle-strengthening exercise with sleep quality among a large sample of community-dwelling adults, it is currently unknown how these findings translate to the population level. This study describes the associations between the weekly frequency of muscle-strengthening exercise and sleep quality among a nationally representative sample of German adults. Data were drawn for the 2014 German Health Update Survey (n = 23,635; ≥18 years). Validated survey items assessed muscle-strengthening exercise (times/week) and sleep quality (assessed via 4 point-scale: ' very poor ' to ' good '). Poisson regression with robust error variance was used to calculate prevalence ratios of (PR) across weekly muscle-strengthening exercise frequency (None [reference]; 1, 2, 3-4 and ≥ 5 times/week), adjusting for potential confounders (e.g. age, sex, socioeconomic status, self-rated health, smoking, alcohol, aerobic physical activity). Compared with those reporting none, any muscle-strengthening exercise was associated with a reduced prevalence of ' poor ' (PR range: 0.77-0.83) and ' very poor ' (PR range: 0.57-0.70) quality sleep. Future health behavior modification strategies to enhance sleep quality at the population-level should consider promoting muscle-strengthening exercise., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Authors.)

Objective: Muscle-strengthening exercise (use of weight machines, free weights, push-ups, sit-ups), has multiple independent health benefits, and is a component of the Global physical activity guidelines. However, there is currently a lack of multi-country muscle-strengthening exercise prevalence studies. This study describes the prevalence and correlates of muscle-strengthening exercise across multiple European countries., Methods: Data were drawn from the European Health Interview Survey Wave 2 (2013-14), which included nationally representative samples (n = 3,774-24,016) from 28 European countries. Muscle-strengthening exercise was assessed using the European Health Interview Survey Physical Activity Questionnaire. Population-weighted proportions were calculated for (1) "insufficient" (0-1 days/week) or (2) "sufficient" muscle-strengthening exercise (≥2 days/week). Prevalence ratios were calculated using multivariate Poisson regression for those reporting sufficient muscle-strengthening by country and by sociodemographic/lifestyle characteristics (sex, age, education, income, self-rated health etc.)., Results: Data were available for 280,605 European adults aged ≥18 years. Overall, 17.3% (95% CI = 17.1%-17.5%) reported sufficient muscle-strengthening exercise (≥2 days/week). Muscle-strengthening exercise was geographically patterned with the lowest prevalence reported in South-eastern European countries (Romania, Malta and Cyprus: range: 0.7%-7.4%), and the highest prevalence in the Nordic countries (Iceland, Sweden, and Denmark: range: 34.1%-51.6%). Older age, insufficient aerobic activity, poorer self-rated health, lower income/education, being female, and being overweight/obese were significantly associated with lower likelihood of reporting sufficient muscle-strengthening exercise, independently of other characteristics., Conclusions: Most European adults do not report sufficient muscle-strengthening exercise, and prevalence estimates varied considerably across countries. Low participation in muscle-strengthening exercise is widespread across Europe, and warrants public health attention., Competing Interests: The authors have declared that no competing interests exist.

This current opinion provides an overview of the emerging discipline of muscle-strengthening exercise epidemiology. First, we define muscle-strengthening exercise, and discuss its recent addition into the global physical activity guidelines, which were historically mainly focused on aerobic physical activity (walking, running, cycling etc.). Second, we provide an overview of the current clinical and epidemiological evidence on the associations between muscle-strengthening exercise and health, showing a reduced mortality risk, and beneficial cardiometabolic, musculoskeletal, functional and mental health-related outcomes. Third, we describe the latest epidemiological research on the assessment, prevalence, trends and correlates of muscle-strengthening exercise. An overview of recent population estimates suggests that the proportion of adults meeting the current muscle-strengthening exercise guideline (10-30%; ≥ 2 sessions/week) is far lower than adults reporting meeting the aerobic exercise guideline (~ 50%; ≥ 150 min/week). Fourth, we discuss the complexity of muscle-strengthening exercise promotion, highlighting the need for concurrent, coordinated, and multiple-level strategies to increase population-level uptake/adherence of this exercise modality. Last, we explore key research gaps and strategies that will advance the field of muscle-strengthening exercise epidemiology. Our objective is to provide a case for increased emphasis on the role of muscle-strengthening exercise for chronic disease prevention, and most importantly, stimulate more research in this currently understudied area of physical activity epidemiology.

Objective: Both aerobic physical activity and muscle-strengthening exercise are recommended for obesity prevention. However, at the population level, the independent and/or combined associations of these physical activity modalities with obesity are unknown. The aim of this study was to examine the associations between aerobic physical activity and muscle-strengthening exercise with obesity among a representative sample of adults., Methods: Data were pooled from four US public health surveillance surveys from 2011 to 2017. Cross-sectional associations between adherence to the aerobic physical activity (≥ 150 min/wk) and muscle-strengthening exercise (≥ 2 times/wk) guidelines with different classes of BMI-defined obesity were examined using Poisson regression. Prevalence ratios are reported as both unadjusted and adjusted for sociodemographic and lifestyle characteristics., Results: Data were available for 1,677,108 adults (≥ 18 years old). Compared with meeting neither guideline (reference category), meeting both guidelines was associated with the lowest adjusted prevalence ratios (APRs) for the following: Class I obesity and above (BMI ≥ 30.0 kg/m 2 ), APR = 0.54 (95% CI: 0.53-0.54); Class II obesity and above (BMI ≥ 35.0 kg/m 2 ), APR = 0.32 (95% CI: 0.31-0.33); and Class III obesity and above (BMI ≥ 40.0 kg/m 2 ), APR = 0.21 (95% CI: 0.20-0.21)., Conclusions: Among nearly 1.7 million US adults, meeting both aerobic and muscle-strengthening exercise guidelines was associated with a lower obesity prevalence, and associations were more pronounced for higher obesity classes., (© 2019 The Obesity Society.)

The development in research concerning sedentary behaviour has been rapid over the past two decades. This has led to the development of evidence and views that have become more advanced, diverse and, possibly, contentious. These include the effects of standing, the breaking up of prolonged sitting and the role of moderate-to-vigorous physical activity (MVPA) in the association between sedentary behaviour and health outcomes. The present aim is to report the views of experts (n = 21) brought together (one-day face-to-face meeting in 2018) to consider these issues and provide conclusions and recommendations for future work. Each topic was reviewed and presented by one expert followed by full group discussion, which was recorded, transcribed and analysed. The experts concluded that (a). standing may bring benefits that accrue from postural shifts. Prolonged (mainly static) standing and prolonged sitting are both bad for health; (b). 'the best posture is the next posture'. Regularly breaking up of sitting with postural shifts and movement is vital; (c). health effects of prolonged sitting are evident even after controlling for MVPA, but high levels of MVPA can attenuate the deleterious effects of prolonged sitting depending on the health outcome of interest. Expert discussion addressed measurement, messaging and future directions., Competing Interests: The authors declare no conflict of interest.

Background: The World Health Organization's 'Global Recommendations on Physical Activity for Health' state that adults should engage in regular moderate-to-vigorous intensity aerobic physical activity (MVPA; e.g. walking, running, cycling) and muscle-strengthening activity (MSA; e.g. strength/resistance training). However, assessment of both MVPA and MSA is rare in physical activity surveillance. The aim of this study is to describe the prevalence, correlates and chronic health conditions associated with meeting the combined MVPA-MSA guidelines among a population representative sample of U.S. adults., Methods: In this cross-sectional study, data were drawn from the U.S. 2015 Behavioral Risk Factor Surveillance System. During telephone interviews, MVPA and MSA were assessed using validated questionnaires. We calculated the proportions meeting both the global MVPA and MSA physical activity guidelines (MVPA ≥150 min/week and MSA ≥2 sessions/week). Poisson regressions with a robust error variance were used to assess: (i) prevalence ratios (PR) for meeting both guidelines across sociodemographic factors (e.g. age, sex, education, income, race/ethnicity); and (ii) PRs of 12 common chronic health conditions (e.g. diabetes, coronary heart disease, hypertension, depression) across different categories of physical activity guideline adherence (met neither [reference]; MSA only; MVPA only; met both)., Results: Among 383,928 adults (aged 18-80 years), 23.5% (95% CI: 20.1, 20.6%) met the combined MVPA-MSA guidelines. Those with poorer self-rated health, older adults, women, lower education/income and current smokers were less likely to meet the combined guidelines. After adjustment for covariates (e.g. age, self-rated health, income, smoking) compared with meeting neither guidelines, MSA only and MVPA only, meeting the combined MVPA-MSA guidelines was associated with the lowest PRs for all health conditions (APR range: 0.44-0.76), and the clustering of ≥6 chronic health conditions (APR = 0.33; 95% CI: 0.31-0.35)., Conclusions: Eight out of ten U.S. adults do not meet the global physical activity guidelines. This study supports the need for comprehensive health promotion strategies to increase the uptake and adherence of MVPA-MSA among U.S. adults. Large-scale interventions should target specific population sub-groups including older adults, women, those with poorer health and lower education/income.

Background: The number of deaths per year attributed to non-communicable diseases is increasing in low- and middle-income countries, including Thailand. To facilitate the development of evidence-based public health programs and policies in Thailand, research on physical activity (PA) and sedentary behaviour (SB) is needed. The aims of this scoping review were to: (i) map all available evidence on PA and SB in Thailand; (ii) identify research gaps; and (iii) suggest directions for future research., Methods: A systematic literature search was conducted through 10 bibliographic databases. Additional articles were identified through secondary searches of reference lists, websites of relevant Thai health organisations, Google, and Google Scholar. Studies written in Thai or English were screened independently by two authors and included if they presented quantitative or qualitative data relevant to public health research on PA and/or SB., Results: Out of 25,007 screened articles, a total of 564 studies were included in the review. Most studies included PA only (80%), 6.7% included SB only, and 13.3% included both PA and SB. The most common research focus was correlates (58.9%), followed by outcomes of PA/SB (22.2%), prevalence of PA/SB (12.4%), and instrument validation (3.2%). Most PA/SB research was cross-sectional (69.3%), while interventions (19.7%) and longitudinal studies (2.8%) were less represented. Most studies (94%) used self-reports of PA/SB, and few (2.5%) used device-based measures. Both sexes were examined in most studies (82.5%). Adults were the main target population group (51.1%), followed by older adults (26.9%), adolescents (15.7%), and children (6.3%). Clinical populations were investigated in the context of PA/SB in a relatively large number of studies (15.3%), most frequently those with cardiovascular disease, diabetes, and hypertension (22%, 21%, and 21% respectively)., Conclusions: The number of Thai papers on PA published per year has been increasing, indicating a growing interest in this research area. More studies using population-representative samples are needed, particularly among children and adolescents, and investigating SB as a health risk factor. To provide stronger evidence on determinants and outcomes of PA/SB, longitudinal studies using standardised measures of PA and SB are required.

Prolonged sitting has been linked to adverse health outcomes; therefore, we developed and examined a web-based, computer-tailored workplace sitting intervention. As we had previously shown good effectiveness, the next stage was to conduct a dissemination study. This study reports on the dissemination efforts of a health promotion organisation, associated costs, reach achieved, and attributes of the website users. The organisation systematically registered all the time and resources invested to promote the intervention. Website usage statistics (reach) and descriptive statistics (website users' attributes) were also assessed. Online strategies (promotion on their homepage; sending e-mails, newsletters, Twitter, Facebook and LinkedIn posts to professional partners) were the main dissemination methods. The total time investment was 25.6 h, which cost approximately 845 EUR in salaries. After sixteen months, 1599 adults had visited the website and 1500 (93.8%) completed the survey to receive personalized sitting advice. This sample was 38.3 ± 11.0 years, mainly female (76.9%), college/university educated (89.0%), highly sedentary (88.5% sat >8 h/day) and intending to change (93.0%) their sitting. Given the small time and money investment, these outcomes are positive and indicate the potential for wide-scale dissemination. However, more efforts are needed to reach men, non-college/university educated employees, and those not intending behavioural change.

Background: In recent decades, the evidence supporting the physical and mental health benefits of holistic movement practices such as yoga and t'ai chi have become increasingly established. Consequently, investigating the participation prevalence and patterns of these practices is a relevant pursuit in the public health field. Few studies have provided population-level assessment of participation rates, however, and even fewer have focused on patterns over time. The purpose of this study was to examine participation prevalence and trends in yoga/Pilates and t'ai chi/qigong over a ten-year period in a nationally representative sample of Australians aged 15 years and over, with particular attention to sex and age. A secondary purpose was to juxtapose these findings with participation trends in traditional fitness activities over the same period., Methods: Data comprised modes and types of physical activity, age, and sex variables collected through the Exercise, Recreation and Sport Survey (ERASS), a series of independent cross-sectional Australia-wide surveys conducted yearly between 2001 and 2010. For each year, weighted population estimates were calculated for those participating in yoga/Pilates, t'ai chi/qigong, and fitness activities (e.g. aerobics, calisthenics). Linear regression and multiple logistic regression analyses were used to examine trends in prevalence rates over time and differences among sex and age (15-34; 35-54; 55+ years) groups, respectively., Results: Average prevalence rates between 2001 and 2010 were 3.0% (95% CI 2.9-3.1) for yoga/Pilates, 0.6% (95% CI 0.5-0.6) for t'ai chi/qigong, and 19.2% (95% CI 18.9-19.4) for fitness activities. Across the decade, overall participation rates remained relatively stable for yoga/Pilates and t'ai chi/qigong, while increasing linearly for fitness activities. For both genders and in all three age groups, participation in fitness activities increased, whereas only in the 55+ age group was there a significant increase in yoga/Pilates participation; participation in t'ai chi/qigong declined significantly in the two younger age groups., Conclusions: Participation rates in yoga/Pilates and t'ai chi/qigong in Australia were low and relatively stable. As fitness activities increased in popularity across the decade, holistic movement practices did not. These findings point to the need to investigate activity-specific barriers and facilitators to participation, including intrapersonal, interpersonal, organisational, and environmental factors.

Background: Sedentary behaviours (time spent sitting, with low energy expenditure) are associated with deleterious health outcomes, including all-cause mortality. Whether this association can be considered causal has yet to be established. Using systematic reviews and primary studies from those reviews, we drew upon Bradford Hill's criteria to consider the likelihood that sedentary behaviour in epidemiological studies is likely to be causally related to all-cause (premature) mortality., Methods: Searches for systematic reviews on sedentary behaviours and all-cause mortality yielded 386 records which, when judged against eligibility criteria, left eight reviews (addressing 17 primary studies) for analysis. Exposure measures included self-reported total sitting time, TV viewing time, and screen time. Studies included comparisons of a low-sedentary reference group with several higher sedentary categories, or compared the highest versus lowest sedentary behaviour groups. We employed four Bradford Hill criteria: strength of association, consistency, temporality, and dose-response. Evidence supporting causality at the level of each systematic review and primary study was judged using a traffic light system depicting green for causal evidence, amber for mixed or inconclusive evidence, and red for no evidence for causality (either evidence of no effect or no evidence reported)., Results: The eight systematic reviews showed evidence for consistency (7 green) and temporality (6 green), and some evidence for strength of association (4 green). There was no evidence for a dose-response relationship (5 red). Five reviews were rated green overall. Twelve (67 %) of the primary studies were rated green, with evidence for strength and temporality., Conclusions: There is reasonable evidence for a likely causal relationship between sedentary behaviour and all-cause mortality based on the epidemiological criteria of strength of association, consistency of effect, and temporality.

Background: Leisure-time physical activity and strength training participation levels are low and socioeconomically distributed. Fitness trainers (e.g. gym/group instructors) may have a role in increasing these participation levels. However, it is not known whether the training location and characteristics of Australian fitness trainers vary between areas that differ in socioeconomic status., Methods: In 2014, a sample of 1,189 Australian trainers completed an online survey with questions about personal and fitness industry-related characteristics (e.g. qualifications, setting, and experience) and postcode of their usual training location. The Australian Bureau of Statistics 'Index of Relative Socioeconomic Disadvantage' (IRSD) was matched to training location and used to assess where fitness professionals trained and whether their experience, qualification level and delivery methods differed by area-level disadvantage. Linear regression analysis was used to examine the relationship between IRSD score and selected characteristics adjusting for covariates (e.g. sex, age)., Results: Overall, 47 % of respondents worked in areas within the three least-disadvantaged deciles. In contrast, only 14.8 % worked in the three most-disadvantaged deciles. In adjusted regression models, fitness industry qualification was positively associated with a higher IRSD score (i.e. working in the least-disadvantaged areas) (Cert III: ref; Cert IV β:13.44 [95 % CI 3.86-23.02]; Diploma β:15.77 [95 % CI: 2.17-29.37]; Undergraduate β:23.14 [95 % CI: 9.41-36.86])., Conclusions: Fewer Australian fitness trainers work in areas with high levels of socioeconomic disadvantaged areas than in areas with low levels of disadvantage. A higher level of fitness industry qualifications was associated with working in areas with lower levels of disadvantage. Future research should explore the effectiveness of providing incentives that encourage more fitness trainers and those with higher qualifications to work in more socioeconomically disadvantaged areas.

Objective: The current Australian Physical Activity Guidelines recommend that adults engage in regular muscle-strengthening activity (e.g. strength or resistance training). However, public health surveillance studies describing the patterns and trends of population-level muscle-strengthening activity participation are sparse. The aim of this study is to examine the prevalence, trends and sociodemographic correlates of muscle-strengthening activity participation in a national-representative sample of Australians aged 15 years and over., Methods: Between 2001 and 2010, quarterly cross-sectional national telephone surveys were conducted as part of the Australian Sports Commission's 'Exercise, Recreation and Sport Survey'. Pooled population-weighted proportions were calculated for reporting: [i] no muscle-strengthening activity; [ii] insufficient muscle-strengthening activity, and [iii] sufficient muscle-strengthening activity. Associations with sociodemographic variables were assessed using multiple logistic regression analyses., Results: Out of 195,926 participants, aged 15-98 years, only 10.4% (95% CI: 10.1-10.7) and 9.3% (95% CI: 9.1-9.5) met the muscle-strengthening activity recommendations in the past two weeks and in the past year, respectively. Older adults (50+ years), and those living in socioeconomically disadvantaged, outer regional/remote areas and with lower education were less likely to report sufficient muscle-strengthening activity (p<0.001). Over the 10-year monitoring period, there was a significant increase in the prevalence of sufficient muscle-strengthening activity (6.4% to 12.0%, p-value for linear trend <0.001)., Conclusions: A vast majority of Australian adults did not engage in sufficient muscle-strengthening activity. There is a need for public health strategies to support participation in muscle-strengthening activity in this population. Such strategies should target older and lower educated adults, and those living in socioeconomically disadvantaged, outer regional/remote and areas.

Background: The current Australia's Physical Activity and Sedentary Behaviour Guidelines recommend that adults engage in regular moderate-to-vigorous-intensity physical activity (MVPA) and strength training (ST), and minimise time spent in sedentary behaviours (SB). However, evidence about the specific individual and concurrent distribution of these behaviours in Australia is scarce. Therefore, the aim of this study was to determine the prevalence and sociodemographic correlates of MVPA, ST and SB in a national-representative sample of Australian adults., Methods: Data were collected using face-to-face interviews, as part of the National Nutrition and Physical Activity Survey 2011-12. The population-weighted proportions meeting the MVPA (≥ 150 min/week), ST (≥ 2 sessions/week) and combined MVPA-ST guidelines, and proportions classified as having 'low levels of SB' (< 480 min/day) were calculated, and their associations with selected sociodemographic and health-related variables were assessed using multiple logistic regression analyses. This was also done for those at potentially 'high-risk', defined as insufficient MVPA-ST and 'high-sedentary' behaviour., Results: Out of 9345 participants (response rate = 77.0 %), aged 18-85 years, 52.6 % (95 % CI: 51.2 %-54.0 %), 18.6 % (95 % CI: 17.5 %-19.7 %) and 15.0 % (95 % CI: 13.9 %-16.1 %) met the MVPA, ST and combined MVPA-ST guidelines, respectively. Female gender, older age, low/medium education, poorer self-rated health, being classified as underweight or obese, and being a current smoker were independently associated with lower odds of meeting the MVPA, ST and combined MVPA-ST guidelines. A total of 78.9 % (95 % CI: 77.9 %-80.0 %) were classified as having low levels of SB. Females, older adults and those with lower education were more likely to report lower levels of SB, whilst those with poor self-rated health and obese individuals were less likely to report lower levels of SB (i.e. SB = ≥ 480 min/day). A total of 8.9 % (95 % CI: 8.1 %-9.6 %) were categorised as individuals at potentially 'high-risk'. Those with poorer self-rated health, obese individuals, those aged 25-44, and current smokers were more likely to be in the 'high risk' group., Conclusions: The large majority of Australian adults do not meet the full physical activity guidelines and/or report excessive SB. Our results call for public health interventions to reduce physical inactivity and SB in Australia, particularly among the subgroups at the highest risk of these unhealthy behaviours.

Objective: To describe the total and domain-specific daily sitting time among a sample of Australian office-based employees., Methods: In April 2010, paper-based surveys were provided to desk-based employees (n=801) in Victoria, Australia. Total daily and domain-specific (work, leisure-time and transport-related) sitting time (minutes/day) were assessed by validated questionnaires. Differences in sitting time were examined across socio-demographic (age, sex, occupational status) and lifestyle characteristics (physical activity levels, body mass index [BMI]) using multiple linear regression analyses., Results: The median (95% confidence interval [CI]) of total daily sitting time was 540 (531-557) minutes/day. Insufficiently active adults (median=578 minutes/day, [95%CI: 564-602]), younger adults aged 18-29 years (median=561 minutes/day, [95%CI: 540-577]) reported the highest total daily sitting times. Occupational sitting time accounted for almost 60% of total daily sitting time. In multivariate analyses, total daily sitting time was negatively associated with age (unstandardised regression coefficient [B]=-1.58, p<0.001) and overall physical activity (minutes/week) (B=-0.03, p<0.001) and positively associated with BMI (B=1.53, p=0.038)., Conclusions: Desk-based employees reported that more than half of their total daily sitting time was accrued in the work setting., Implications: Given the high contribution of occupational sitting to total daily sitting time among desk-based employees, interventions should focus on the work setting., (© 2014 Public Health Association of Australia.)

Background: Breaks in prolonged sitting may have beneficial cardiometabolic and musculoskeletal health outcomes. Desk-based work settings are an important environment to promote and support breaks in sitting time. However, few studies have reported the psychometric properties of self-report measures to assess the frequency and duration of breaks from sitting. This study examined the concurrent validity and test-retest reliability of the Workplace Sitting Breaks Questionnaire (SITBRQ) designed to assess frequency and duration of breaks in sitting within desk-based work settings., Methods: To assess the concurrent validity, a sample of 147 desk-based employees completed the SITBRQ and wore an Actigraph GT1M accelerometer for seven consecutive days. To establish test-retest reliability, SITBRQ was administered on two separate occasions 7-14 days apart to a separate sample of 96 desk-based employees., Results: A low relative agreement with accelerometry (Spearman's r = 0.24 [95% CI 0.07-0.40]) was determined for self-reported frequency, but not for the duration of sitting breaks (Spearman's r = 0.05 [95% CI -0.12-0.22]). Adequate reliability was determined for both self-reported frequency (Spearman's r = 0.71 [95% CI 0.59-0.79], Cohen's kappa = 0.74 [95% CI 0.64-0.84]) and duration of sitting breaks (Spearman's r = 0.59 [95% CI 0.45-0.71], Cohen's kappa = 0.61 [95% CI 0.38-0.85])., Conclusion: SITBRQ may be used for assessment of the frequency of sitting breaks within desk-based work settings with validity and reliability similar to other self-reports in the field of sedentary behaviour research. However, until adequately improved and re-evaluated, it should not be used to collect data about the duration of breaks in sitting time.

The Na+,K+-ATPase (NKA) plays a fundamental role in the regulation of skeletal muscle membrane Na+ and K+ gradients, excitability and fatigue during repeated intense contractions. Many studies have investigated the effects of acute concentric exercise on K+ regulation and skeletal muscle NKA, but almost nothing is known about the effects of repeated eccentric contractions. We therefore investigated the effects of unaccustomed maximal eccentric knee extensor contractions on K+ regulation during exercise, peak knee extensor muscle torque, and vastus lateralis muscle NKA content and 3-O-MFPase activity. Torque measurements, muscle biopsies, and venous blood samples were taken before, during and up to 7 days following the contractions in six healthy adults. Eccentric contractions reduced peak isometric muscle torque immediately post-exercise by 26±11% and serum creatine kinase concentration peaked 24 h post-exercise at 339±90 IU/L. During eccentric contractions, plasma [K+] rose during Set 1 and remained elevated at ∼4.9 mM during sets 4-10; this was despite a decline in work output by Set 4, which fell by 18.9% at set 10. The rise in plasma [K+] x work(-1) ratio was elevated over Set 2 from Set 4- Set 10. Eccentric contractions had no effect on muscle NKA content or maximal in-vitro 3-O-MFPase activity immediately post- or up to 7 d post-exercise. The sustained elevation in plasma [K+] despite a decrease in work performed by the knee extensor muscles suggests an impairment in K+ regulation during maximal eccentric contractions, possibly due to increased plasma membrane permeability or to excitation-contraction uncoupling.

Background: Prolonged sitting is an emerging health risk. However, multi-country comparative sitting data are sparse. This paper reports the prevalence and correlates of sitting time in 32 European countries., Methods: Data from the Eurobarometer 64.3 study were used, which included nationally representative samples (n = 304-1,102) from 32 European countries. Face-to-face interviews were conducted during November and December 2005. Usual weekday sitting time was assessed using the International Physical Activity Questionnaire (short-version). Sitting time was compared by country, age, gender, years of education, general health status, usual activity and physical activity. Multivariable-adjusted analyses assessed the odds of belonging to the highest sitting quartile., Results: Data were available for 27,637 adults aged 15-98 years. Overall, mean reported weekday sitting time was 309 min/day (SD 184 min/day). There was a broad geographical pattern and some of the lowest amounts of daily sitting were reported in southern (Malta and Portugal means 194-236 min/day) and eastern (Romania and Hungary means 191-276 min/day) European countries; and some of the highest amounts of daily sitting were reported in northern European countries (Germany, Benelux and Scandinavian countries; means 407-335 min/day). Multivariable-adjusted analyses showed adults with low physical activity levels (OR = 5.10, CI₉₅ = 4.60-5.66), those with high sitting in their main daily activity (OR = 2.99, CI₉₅ = 2.74-3.25), those with a bad/very bad general health state (OR = 1.87, CI₉₅ = 1.63-2.15) and higher education levels (OR = 1.48, CI₉₅ = 1.38-1.59) were more likely to be in the highest quartile of daily sitting time. Adults within Greece (OR = 2.91, CI₉₅ = 2.51-3.36) and Netherlands (OR = 2.56, CI₉₅ = 2.22-2.94) were most likely to be in the highest quartile. High-sit/low-active participants comprised 10.1% of the sample. Adults self-reporting bad/very bad general health state (OR = 4.74, CI₉₅ = 3.97-5.65), those within high sitting in their main daily activities (OR = 2.87, CI₉₅ = 2.52-3.26) and adults aged ≥65 years (OR = 1.53, CI₉₅ = 1.19-1.96) and were more likely to be in the high-sit/low-active group., Conclusions: Weekday sitting time and its demographic correlates varied considerably across European countries, with adults in north-western European countries sitting the most. Sitting is prevalent across Europe and merits attention by preventive interventions.