Electromyography-based fatigue assessment of an upper body exoskeleton during automotive assembly.

The purpose of this study was to assess an upper body exoskeleton during automotive assembly processes that involve elevated arm postures. Sixteen team members at Toyota Motor Manufacturing Canada were fitted with a Levitate Airframe, and each team member performed between one and three processes with and without the exoskeleton. A total of 16 assembly processes were studied. Electromyography (EMG) data were collected on the anterior deltoid, biceps brachii, upper trapezius, and erector spinae. Team members also completed a usability survey. The exoskeleton significantly reduced anterior deltoid mean active EMG amplitude (p = .01, Δ = -3.2 %MVC, d = 0.56 medium effect) and fatigue risk value (p < .01, Δ = -5.1 %MVC, d = 0.62 medium effect) across the assembly processes, with no significant changes for the other muscles tested. A subset of nine assembly processes with a greater amount of time spent in arm elevations at or above 90° (30 vs. 24%) and at or above 135° (18 vs. 9%) appeared to benefit more from exoskeleton usage. For these processes, the exoskeleton significantly reduced anterior deltoid mean active EMG amplitude (p < .01, Δ = -5.1 %MVC, d = 0.95 large effect) and fatigue risk value (p < .01, Δ = -7.4 %MVC, d = 0.96 large effect). Team members responded positively about comfort and fatigue benefits, although there were concerns about the exoskeleton hindering certain job duties. The results support quantitative testing to match exoskeleton usage with specific job tasks and surveying team members for perceived benefits/drawbacks.

Factors predicting the mental health of adolescents attending a faith-based Australian school system: a multi-group structural equation analysis.

Background: Adolescents attending Seventh-day Adventist schools (Adventist) in Australia tend to experience good health and exhibit better health behaviors than national norms, however few studies have investigated factors predicting their mental health.Aims: The aim of this study was to explore the complex network of factors that predict the mental health status (MHS) of adolescents attending Adventist schools in Australia.Methods: A survey instrument was used to collect data from 1527 secondary school students attending Adventist schools across Australia. Structural equation modeling was employed to examine concomitantly the direct and indirect effects of childhood experiences, present attitudes and selected health behaviors on MHS.Results: Childhood family dynamics had the strongest association with MHS (ßtotal = 0.33) followed by a sense of meaning and purpose (ßtotal = 0.27), perceived social misfit status (ßtotal = -0.19), and school academic performance (ßtotal = 0.18). Multi-group analysis found significant pathway differences in the model for gender with regards to the association of meaning and purpose, physical activity and sleep quantity with MHS.Conclusions: The outcomes of the study highlight the importance of early positive childhood family dynamics and the discovery of meaning and purpose during adolescence to promote positive mental health among adolescents.

The association between self-rated health and social environments, health behaviors and health outcomes: a structural equation analysis.

BACKGROUND: The factors shaping the health of the current generation of adolescents are multi-dimensional and complex. The purpose of this study was to explore the determinants of self-rated health (SRH) of adolescents attending a faith-based school system in Australia. METHODS: A total of 788 students attending 21 Seventh-day Adventist schools in Australia responded to a health and lifestyle survey that assessed SRH as well as potential determinants of SRH including the health outcomes mental health, vitality, body mass index (BMI), select health behaviors, social factors and personal demographics. Structural equation modeling was used to analyze the data and examine the direct and indirect effects of these factors on SRH. RESULTS: The structural model developed was a good fit with the data. The health outcome mental health had the strongest association with SRH (ß = 0.17). Several upstream variables were also associated with higher SRH ratings. The health behavior sleep hours had the strongest association with SRH (ßtotal = 0.178) followed by fruit/vegetable consumption (ßtotal = 0.144), physical activity (ßtotal = 0.135) and a vegetarian diet (ßtotal = 0.103). Of the demographic and social variables measured, adverse childhood experiences (ACEs) had the strongest association with SRH (ßtotal = - 0.125), negatively influencing SRH, and gender also associated with an increase in SRH (ßtotal = 0.092), with the influence of these factors being mediated through other variables in the model. CONCLUSIONS: This study presents a conceptual model that illustrates the complex network of factors concomitantly associated with SRH in adolescents. The outcomes of the study provide insights into the determinants of adolescent SRH which may inform priority areas for improving this construct.

Religious Affiliation Influences on the Health Status and Behaviours of Students Attending Seventh-Day Adventist Schools in Australia.

Students attending Seventh-day Adventist (Adventist) schools in Australia have been shown to have better health status and behaviours compared to secular norms, yet these schools cater for a high percentage of non-Adventist students. The purpose of this study was to investigate the influence of religious affiliation (Adventist/non-Adventist) on the health status and behaviours of students attending Adventist secondary schools in Australia. The sample included 1734 students who responded to a health and lifestyle survey that captured demographic details, self-reported height and weight, self-reported health status, mental health and select health behaviours. Students who identified themselves as Adventist reported significantly better health behaviours than the non-Adventist students in several behavioural domains, especially among the male students. However, this did not translate to a difference in health status. Further research is needed to understand the causal mechanisms responsible for the potential health advantage of Adventist students, which may include family or church religious influences.

The Body Mass Index of Adolescents Attending Seventh-Day Adventist Schools in Australia: 2001-2012.

BACKGROUND: We examined the body mass index (BMI) of students attending Seventh-day Adventist (Adventist) schools in Australia in 2001 and 2012. METHODS: A total of 3069 students attending Adventist schools in Australia responded to a health and lifestyle survey in 2001 (N = 1335) and 2012 (N = 1734). The survey captured self-reported height and weight, demographics (age, sex, year level, religion), and select health behaviors. RESULTS: Compared with national norms, lower rates of overweight and obesity were observed in the study cohort, but higher rates of underweight. There was no change in the mean BMI of the students attending Adventist schools in Australia from 2001 to 2012. Regression analyses indicated that a lower BMI was associated with age, sex, more regularly eating breakfast, consuming less soft drink, and having a regular exercise program. The students reported a high consumption of fruits, vegetables, and whole grains compared with Australian national norms, and 29% claimed to be vegetarian. CONCLUSIONS: Students attending Adventist schools appear to have a lower prevalence of overweight and obesity than the secular population, but a higher prevalence of underweight. The mechanisms through which Adventist schools may influence student's BMI warrants further investigation.

Are strict vegetarians protected against prostate cancer?

BACKGROUND: According to the American Cancer Society, prostate cancer accounts for ∼27% of all incident cancer cases among men and is the second most common (noncutaneous) cancer among men. The relation between diet and prostate cancer is still unclear. Because people do not consume individual foods but rather foods in combination, the assessment of dietary patterns may offer valuable information when determining associations between diet and prostate cancer risk. OBJECTIVE: This study aimed to examine the association between dietary patterns (nonvegetarian, lacto-ovo-vegetarian, pesco-vegetarian, vegan, and semi-vegetarian) and prostate cancer incidence among 26,346 male participants of the Adventist Health Study-2. DESIGN: In this prospective cohort study, cancer cases were identified by matching to cancer registries. Cox proportional hazards regression analysis was performed to estimate HRs by using age as the time variable. RESULTS: In total, 1079 incident prostate cancer cases were identified. Around 8% of the study population reported adherence to the vegan diet. Vegan diets showed a statistically significant protective association with prostate cancer risk (HR: 0.65; 95% CI: 0.49, 0.85). After stratifying by race, the statistically significant association with a vegan diet remained only for the whites (HR: 0.63; 95% CI: 0.46, 0.86), but the multivariate HR for black vegans showed a similar but nonsignificant point estimate (HR: 0.69; 95% CI: 0.41, 1.18). CONCLUSION: Vegan diets may confer a lower risk of prostate cancer. This lower estimated risk is seen in both white and black vegan subjects, although in the latter, the CI is wider and includes the null.

Vegetarian dietary patterns and the risk of colorectal cancers.

IMPORTANCE: Colorectal cancers are a leading cause of cancer mortality, and their primary prevention by diet is highly desirable. The relationship of vegetarian dietary patterns to colorectal cancer risk is not well established. OBJECTIVE: To evaluate the association between vegetarian dietary patterns and incident colorectal cancers. DESIGN, SETTING, AND PARTICIPANTS: The Adventist Health Study 2 (AHS-2) is a large, prospective, North American cohort trial including 96,354 Seventh-Day Adventist men and women recruited between January 1, 2002, and December 31, 2007. Follow-up varied by state and was indicated by the cancer registry linkage dates. Of these participants, an analytic sample of 77,659 remained after exclusions. Analysis was conducted using Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. The analysis was conducted between June 1, 2014, and October 20, 2014. EXPOSURES: Diet was assessed at baseline by a validated quantitative food frequency questionnaire and categorized into 4 vegetarian dietary patterns (vegan, lacto-ovo vegetarian, pescovegetarian, and semivegetarian) and a nonvegetarian dietary pattern. MAIN OUTCOMES AND MEASURES: The relationship between dietary patterns and incident cancers of the colon and rectum; colorectal cancer cases were identified primarily by state cancer registry linkages. RESULTS: During a mean follow-up of 7.3 years, 380 cases of colon cancer and 110 cases of rectal cancer were documented. The adjusted hazard ratios (HRs) in all vegetarians combined vs nonvegetarians were 0.78 (95% CI, 0.64-0.95) for all colorectal cancers, 0.81 (95% CI, 0.65-1.00) for colon cancer, and 0.71 (95% CI, 0.47-1.06) for rectal cancer. The adjusted HR for colorectal cancer in vegans was 0.84 (95% CI, 0.59-1.19); in lacto-ovo vegetarians, 0.82 (95% CI, 0.65-1.02); in pescovegetarians, 0.57 (95% CI, 0.40-0.82); and in semivegetarians, 0.92 (95% CI, 0.62-1.37) compared with nonvegetarians. Effect estimates were similar for men and women and for black and nonblack individuals. CONCLUSIONS AND RELEVANCE: Vegetarian diets are associated with an overall lower incidence of colorectal cancers. Pescovegetarians in particular have a much lower risk compared with nonvegetarians. If such associations are causal, they may be important for primary prevention of colorectal cancers.

Recruiting and motivating black subjects to complete a lengthy survey in a large cohort study: an exploration of different strategies.

BACKGROUND: The effectiveness of multiple innovative recruitment strategies for enrolling Black/African American participants to the Adventist Health Study-2 (AHS-2) is described. The study's focus is diet and breast, prostate and colon cancer. METHODS: Promotions centered on trust, relationship building and incentives for increasing enrollment and questionnaire return rate. Of the sub-studies described, one had a randomized control group, and the others, informal controls. The subjects are from all states of the U.S. and some provinces of Canada. The offer of a Black art piece, follow-up calls, a competitive tournament as well as other strategies accounted for nearly 3,000 additional returns even though they were often used in small subsets. RESULTS: Flexibility and multiple strategies proved advantageous in gaining the cooperation of Blacks, who are usually reluctant to participate in research studies. CONCLUSIONS: Lessons learned during initial enrollment should help us retain our final Black cohort of 26,000, and obtain new information when required.

Recruiting black Americans in a large cohort study: the Adventist Health Study-2 (AHS-2) design, methods and participant characteristics.

OBJECTIVE: The goal of the prospective Adventist Health Study-2 (AHS-2) was to examine the relationship between diet and risk of breast, prostate and colon cancers in Black and White participants. This paper describes the study design, recruitment methods, response rates, and characteristics of Blacks in the AHS-2, thus providing insights about effective strategies to recruit Blacks to participate in research studies. DESIGN: We designed a church-based recruitment model and trained local recruiters who used various strategies to recruit participants in their churches. Participants completed a 50-page self-administered dietary and lifestyle questionnaire. PARTICIPANTS: Participants are Black Seventh-day Adventists, aged 30-109 years, and members of 1,209 Black churches throughout the United States and Canada. RESULTS: Approximately 48,328 Blacks from an estimated target group of over 90,000 signed up for the study and 25,087 completed the questionnaire, comprising about 26% of the larger 97,000 AHS-2-member cohort. Participants were diverse in age, geographic location, education, and income. Seventy percent were female with a median age of 59 years. CONCLUSION: In spite of many recruitment challenges and barriers, we successfully recruited a large cohort whose data should provide some answers as to why Blacks have poorer health outcomes than several other ethnic groups, and help explain existing health disparities.

Type of vegetarian diet, body weight, and prevalence of type 2 diabetes.

OBJECTIVE: We assessed the prevalence of type 2 diabetes in people following different types of vegetarian diets compared with that in nonvegetarians. RESEARCH DESIGN AND METHODS: The study population comprised 22,434 men and 38,469 women who participated in the Adventist Health Study-2 conducted in 2002-2006. We collected self-reported demographic, anthropometric, medical history, and lifestyle data from Seventh-Day Adventist church members across North America. The type of vegetarian diet was categorized based on a food-frequency questionnaire. We calculated odds ratios (ORs) and 95% CIs using multivariate-adjusted logistic regression. RESULTS: Mean BMI was lowest in vegans (23.6 kg/m(2)) and incrementally higher in lacto-ovo vegetarians (25.7 kg/m(2)), pesco-vegetarians (26.3 kg/m(2)), semi-vegetarians (27.3 kg/m(2)), and nonvegetarians (28.8 kg/m(2)). Prevalence of type 2 diabetes increased from 2.9% in vegans to 7.6% in nonvegetarians; the prevalence was intermediate in participants consuming lacto-ovo (3.2%), pesco (4.8%), or semi-vegetarian (6.1%) diets. After adjustment for age, sex, ethnicity, education, income, physical activity, television watching, sleep habits, alcohol use, and BMI, vegans (OR 0.51 [95% CI 0.40-0.66]), lacto-ovo vegetarians (0.54 [0.49-0.60]), pesco-vegetarians (0.70 [0.61-0.80]), and semi-vegetarians (0.76 [0.65-0.90]) had a lower risk of type 2 diabetes than nonvegetarians. CONCLUSIONS: The 5-unit BMI difference between vegans and nonvegetarians indicates a substantial potential of vegetarianism to protect against obesity. Increased conformity to vegetarian diets protected against risk of type 2 diabetes after lifestyle characteristics and BMI were taken into account. Pesco- and semi-vegetarian diets afforded intermediate protection.

Missing data in a long food frequency questionnaire: are imputed zeroes correct?

BACKGROUND: Missing data are a common problem in nutritional epidemiology. Little is known of the characteristics of these missing data, which makes it difficult to conduct appropriate imputation. METHODS: We telephoned, at random, 20% of subjects (n = 2091) from the Adventist Health Study-2 cohort who had any of 80 key variables missing from a dietary questionnaire. We were able to obtain responses for 92% of the missing variables. RESULTS: We found a consistent excess of "zero" intakes in the filled-in data that were initially missing. However, for frequently consumed foods, most missing data were not zero, and these were usually not distinguishable from a random sample of nonzero data. Older, black, and less-well-educated subjects had more missing data. Missing data are more likely to be true zeroes in older subjects and those with more missing data. Zero imputation for missing data may create little bias except for more frequently consumed foods, in which case, zero imputation will be suboptimal if there is more than 5%-10% missing. CONCLUSIONS: Although some missing data represent true zeroes, much of it does not, and data are usually not missing at random. Automatic imputation of zeroes for missing data will usually be incorrect, although there is [corrected] little bias unless the foods are frequently consumed. Certain identifiable subgroups have greater amounts of missing data, and require greater care in making imputations.

Comparing self-reported disease outcomes, diet, and lifestyles in a national cohort of black and white Seventh-day Adventists.

INTRODUCTION: Few epidemiologic cohort studies on the etiology of chronic disease are powerful enough to distinguish racial and ethnic determinants from socioeconomic determinants of health behaviors and observed disease patterns. The Adventist Health Study-2 (AHS-2), with its large number of respondents and the variation in lifestyles of its target populations, promises to shed light on these issues. This paper focuses on some preliminary baseline analyses of responses from the first group of participants recruited for AHS-2. METHODS: We administered a validated and pilot-tested questionnaire on various lifestyle practices and health outcomes to 56,754 respondents to AHS-2, comprising 14,376 non-Hispanic blacks and 42,378 non-Hispanic whites. We analyzed cross-sectional baseline data adjusted for age and sex and performed logistic regressions to test differences between responses from the two racial groups. RESULTS: In this Seventh-day Adventist (Adventist) cohort, blacks were less likely than whites to be lifelong vegetarians and more likely to be overweight or obese. Exercise levels were lower for blacks than for whites, but blacks were as likely as whites not to currently smoke or drink. Blacks reported higher rates of hypertension and diabetes than did whites but lower rates of high serum cholesterol, myocardial infarction, emphysema, and all cancers. After we eliminated skin cancer from the analysis, the age-adjusted prevalence of cancer remained significantly lower for black than for white women. The prevalence of prostate cancer was 47% higher for black men than for white men. CONCLUSION: The profile of health habits for black Adventists is better than that for blacks nationally. Given the intractable nature of many other contributors to health disparities, including racism, housing segregation, employment discrimination, limited educational opportunity, and poorer health care, the relative advantage for blacks of the Adventist lifestyle may hold promise for helping to close the gap in health status between blacks and whites nationally.

Stages of sexual readiness and six-month stage progression among African American pre-teens.

We examined the range of sexual intentions and behaviors preceding sexual initiation among 211 African-American pre-teens assigned to the control arm of a longitudinal community-based intervention trial. Stage of sexual readiness was assessed using the stage of change construct from the Transtheoretical Model, and patterns of stage movement during a 6-month period were examined. Overall, 90% of participants were in precontemplation at baseline, with the proportion of participants in this stage declining with each year of age. There was substantial stability in stage of sexual readiness during the 6-month period (87% stable). While definitive conclusions regarding exact patterns of movement are not yet possible, stage movement does not appear to be linear for all pre-teens, and there is evidence of both stage progression and regression. We present emerging patterns of stage movement, which suggest potential variation by age, gender, and baseline stage, and discuss potential implications.

Recruiting blacks to the Adventist health study: Do follow-up phone calls increase response rates?

PURPOSE: To determine whether follow-up phone calls improve response rates to a long questionnaire among black and white subjects. METHODS: Forty black and 39 white Seventh-day Adventist churches were randomized to experimental or control status in a 2:1 ratio favoring the intervention, which is a follow-up phone call to certain church members. Subjects selected from each church were those who had signed up for the Adventist Health Study-2 but not returned a questionnaire 3 months after promotion began. Further returns from a church over the next 3 months, and this increment as a proportion of baseline response, were assessed using t-tests and Poisson regression, respectively. RESULTS: Comparing black experimental and control churches, the mean difference was 5.5 returned questionnaires per church (p < 0.01). Among white churches the mean difference was 3.0 (ns). The baseline-adjusted increment, however, was greater by a factor of 3.37 (95% confidence interval, 1.92, 5.93) in the black experimental relative to control churches, but among white experimental churches was 13% (ns) lower than controls. This difference in response by ethnic group was statistically significant (p < 0.01). CONCLUSION: Follow-up phone calls improved response rates among black subjects only.