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Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2019)

Psychosocial and environmental work factors and their effects on obesity and cardiovascular disease risk among firefighters

By

Javier Garcia Rivas

Doctor of Philosophy in Public Health

University of California, Irvine, 2019

Professor BongKyoo Choi, Chair

During the last two decades, US firefighters have gradually gotten heavier to become the third heaviest occupational group in the country and workplace has been identified as a salient environmental factor which contributes to the development of obesity among this occupational group. Nevertheless, few studies have studied the impact of the work environment and individual characteristics integrated in a socio-ecological model design.

The long term goal of this investigation is to make a contribution to the research of individual, occupational and environmental factors that play a role in the development of obesity in firefighters. The specific aims of this study were to 1) determine the association between worksite food environmental factors and obesity among male firefighters who work 24-hour shifts. 2) investigate the relationship between health-related (nutrition and physical exercise) self-efficacy and weight outcomes i.e. body mass index, waist circumference and body fat percent. Concurrently, analyze important occupational preceding variables (e.g. institutional, supervisor and coworker support) that facilitate/hamper self-efficacy; and 3) compare four sedentary behavior measures (number of steps, <100 and <150 counts per minute threshold in actigraphy, sitting time by posture sensor inclinometer and self-reported sedentary work) with regards to obesity and CVD risk factors.

The present study found an indirect association between environmental fast-food density and obesity indicators in male firefighters. The association was mediated by station- and individual-level eating behaviors. Secondly, organizational support was the most important occupational predictor of exercise and nutrition self-efficacy. However, only exercise self-efficacy was directly associated negatively with all three obesity indicators (Waist circumference, BMI and Body Fat Percent). Finally, self-reported sedentary work was identified as the best predictor of CVD risk factors when compared to other physical activity and sedentary behavior measures. Sitting time assessed by inclinometry was also an important predictor of systolic blood pressure and HDL cholesterol. Other measures of occupational inactivity (step count and sedentary behavior assessed by actigraphy) did not perform well as predictive tools.

The present dissertation offers an integral theoretical approach to a public health issue based on an occupational health perspective in order to prevent weight-related diseases and improve the health of firefighters.

    Cover page: Psychosocial and environmental work factors and their effects on obesity and cardiovascular disease risk among firefighters
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2016)

    Purpose

    This study aims to examine whether body mass index (BMI) overestimates the prevalence of overweight or obese firefighters when compared to waist circumference (WC) and skinfold-based percent body fat (PBF) and to investigate differential relationships of the three adiposity measures with other biological cardiovascular disease (CVD) risk factors.

    Methods

    The adiposity of 355 (347 males and eight females) California firefighters was assessed using three different measures. Other CVD risk factors (high blood pressure, high lipid profiles, high glucose, and low VO2 max) of the firefighters were also clinically assessed.

    Results

    The prevalence of total overweight and obesity was significantly (p < 0.01) higher by BMI (80.4 %) than by WC (48.7 %) and by PBF (55.6 %) in male firefighters. In particular, the prevalence of overweight firefighters was much higher (p < 0.01) by BMI (57.3 %) than by WC (24.5 %) and PBF (38.3 %). 60-64 % of male firefighters who were assessed as normal weight by WC and PBF were misclassified as overweight by BMI. When overweight by BMI was defined as 27.5-29.9 kg/m(2) (vs. the standard definition of 25.0-29.9 kg/m(2)), the agreement of the adiposity classification increased between BMI and other two adiposity measures. Obese firefighters had the highest CVD risk profiles across all three adiposity measures. Only when overweight by BMI was defined narrowly, overweight firefighters had substantially higher CVD risk profiles. Obesity and overweight were less prevalent in female and Asian male firefighters.

    Conclusions

    BMI overestimated the prevalence of total overweight and obesity among male firefighters, compared to WC and skinfold-based PBF. Overweight by BMI needs to be more narrowly defined, or the prevalence of BMI-based overweight (27.5-29.9 kg/m(2)) should be reported additionally for prevention of CVD among male firefighters.
      Cover page: Comparison of body mass index with waist circumference and skinfold-based percent body fat in firefighters: adiposity classification and associations with cardiovascular disease risk factors.Creative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2014)
      Shift work and overtime have been implicated as important work-related risk factors for cardiovascular disease (CVD). Many firefighters who contractually work on a 24-hr work schedule, often do overtime (additional 24-hr shifts) which can result in working multiple, consecutive 24-hr shifts. Very little research has been conducted on firefighters at work that examines the impact of performing consecutive 24-hr shifts on cardiovascular physiology. Also, there have been no standard field methods for assessing in firefighters the cardiovascular changes that result from 24-hr shifts, what we call "cardiovascular strain". The objective of this study, as the first step toward elucidating the role of very long (> 48 hrs) shifts in the development of CVD in firefighters, is to develop and describe a theoretical framework for studying cardiovascular strain in firefighters on very long shifts (i.e., > 2 consecutive 24-hr shifts). The developed theoretical framework was built on an extensive literature review, our recently completed studies with firefighters in Southern California, e-mail and discussions with several firefighters on their experiences of consecutive shifts, and our recently conducted feasibility study in a small group of firefighters of several ambulatory cardiovascular strain biomarkers (heart rate, heart rate variability, blood pressure, salivary cortisol, and salivary C-reactive protein). The theoretical framework developed in this study will facilitate future field studies on consecutive 24-hr shifts and cardiovascular health in firefighters. Also it will increase our understanding of the mechanisms by which shift work or long work hours can affect CVD, particularly through CVD biological risk factors, and thereby inform policy about sustainable work and rest schedules for firefighters.
        Cover page: Very Long (&gt; 48 hours) Shifts and Cardiovascular Strain in Firefighters: a Theoretical Framework
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2014)
        Shift work and overtime have been implicated as important work-related risk factors for cardiovascular disease (CVD). Many firefighters who contractually work on a 24-hr work schedule, often do overtime (additional 24-hr shifts) which can result in working multiple, consecutive 24-hr shifts. Very little research has been conducted on firefighters at work that examines the impact of performing consecutive 24-hr shifts on cardiovascular physiology. Also, there have been no standard field methods for assessing in firefighters the cardiovascular changes that result from 24-hr shifts, what we call cardiovascular strain. The objective of this study, as the first step toward elucidating the role of very long (> 48 hrs) shifts in the development of CVD in firefighters, is to develop and describe a theoretical framework for studying cardiovascular strain in firefighters on very long shifts (i.e., > 2 consecutive 24-hr shifts). The developed theoretical framework was built on an extensive literature review, our recently completed studies with firefighters in Southern California, e-mail and discussions with several firefighters on their experiences of consecutive shifts, and our recently conducted feasibility study in a small group of firefighters of several ambulatory cardiovascular strain biomarkers (heart rate, heart rate variability, blood pressure, salivary cortisol, and salivary C-reactive protein). The theoretical framework developed in this study will facilitate future field studies on consecutive 24-hr shifts and cardiovascular health in firefighters. Also it will increase our understanding of the mechanisms by which shift work or long work hours can affect CVD, particularly through CVD biological risk factors, and thereby inform policy about sustainable work and rest schedules for firefighters.
          Cover page: Very Long (&gt; 48 hours) Shifts and Cardiovascular Strain in Firefighters: a Theoretical Framework.
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