Firefighters With Higher Cardiorespiratory Fitness Demonstrate Lower Markers of Cardiovascular Disease Risk

Hazardous alcohol use and cardiometabolic risk among firefighters

BACKGROUND

Alcohol misuse is prevalent among firefighters, and associated adverse cardiometabolic health consequences could negatively impact readiness for duty. Mental health conditions may confer additional risk. Therefore, we aimed to determine whether alcohol misuse increases cardiometabolic risk among firefighters and whether mental health conditions modify these relationships.

METHODS

Deidentified data from firefighters (N = 2405; 95.8% males, 38 ± 9 years, 29.6 ± 4.6 kg/m2) included demographics, Alcohol Use Disorders Identification Test (AUDIT) and AUDIT-C scores, mental health screening scores, anthropometrics, metabolic panel, and cardiorespiratory testing results. Differences in cardiometabolic parameters between firefighters with low AUDIT-C (<3 [females] or <4 [males]; no or low-risk alcohol use) or high AUDIT-C (≥3 [females] or ≥4 [males]; hazardous alcohol use) were determined and odds ratios for clinical risk factors were calculated. Posttraumatic stress disorder (PTSD), insomnia, depression, and anxiety were assessed as moderators.

RESULTS

Firefighters with high AUDIT-C had significantly (p < 0.05) higher total cholesterol (TC), high-density lipoprotein (HDL-C), and systolic blood pressure (SBP) and diastolic blood pressure (DBP) and lower hemoglobin A1C (HbA1c) than those with low AUDIT-C. In unadjusted and/or adjusted analyses, those with high AUDIT-C had increased risk for overweight/obesity, hypercholesterolemia, and prehypertension/hypertension, and decreased risk for low HDL and elevated HbA1c. There were inverse moderation effects by posttraumatic stress disorder (PTSD), depression, and anxiety on relationships between AUDIT-C score and BP. Insomnia (directly) and anxiety (inversely) moderated relationships between AUDIT-C score and circulating lipids.

CONCLUSIONS

Firefighters with high AUDIT-C have differential cardiometabolic risk, with specific relationships altered by mental health status. Whether higher HDL and lower HbA1c with high AUDIT-C in firefighters is protective long-term remains to be explored. Overall, these results underscore the need for alcohol screening and intervention to maintain cardiometabolic health and long-term occupational readiness among firefighters.

Firefighter Health: A Narrative Review of Occupational Threats and Countermeasures

Structural firefighters are responsible for protecting properties and saving lives during emergency operations. Despite efforts to prepare firefighters for these hazardous occupational demands, the unfortunate reality is that the incidence of health morbidities is increasing within the fire service. Specifically, cardiovascular disease, cancer, and mental health disorders are among the most documented morbidities in firefighters. Pubmed and Google Scholar search engines were used to identify peer-reviewed English language manuscripts that evaluated firefighters' occupational health threats, allostatic factors associated with their occurrence, and evidence-based strategies to mitigate their impact. This narrative review provides fire departments, practitioners, and researchers with evidence-based practices to enhance firefighters' health.

Higher mitochondrial oxidative capacity is the primary molecular differentiator in muscle of rats with high and low intrinsic cardiorespiratory fitness

OBJECTIVE

Cardiorespiratory fitness (CRF) is tightly linked with health and longevity and is implicated in metabolic flexibility and substrate metabolism. The high capacity runner (HCR) and low capacity runner (LCR) rat lines are a genetically heterogeneous rat model selected and bred for CRF that reflect CRF in humans by exhibiting differences in nutrient handling. This study aims to differentiate the intrinsic substrate preference of the HCR compared to LCR rats to better understand the intersection of mitochondrial respiration and intrinsic CRF.

METHODS

We performed bulk skeletal muscle RNA-Sequencing on male and female HCR and LCR rats and assessed the effect of rat line on mitochondrial gene expression pathways using the MitoCarta3.0 database. In a separate cohort of rats, mitochondria were isolated from skeletal and cardiac muscle and maximal oxidation rates were measured using an Oroboros O2k when provided either pyruvate or fatty acid substrates.

RESULTS

The expression of mitochondrial genes are significantly upregulated in HCR skeletal muscle in both male and female rats. In respirometry experiments, fatty acid oxidative capacities were greater in HCR compared to LCR, and male compared to female rats, as a function of both mitochondrial quality and mitochondrial density. This effect was greater in the skeletal muscle than in the heart. Pyruvate oxidation did not differ significantly between lines.

CONCLUSIONS

The capacity for increased fatty acid oxidation in the HCR rat is a result of selection for running capacity and is likely a key contributor to the healthy metabolic phenotype of individuals with high CRF.

Association between Cardiovascular and Musculoskeletal Health in Firefighters

OBJECTIVE

The aim of the study is to determine the association between cardiovascular health (CVH) and musculoskeletal health in firefighters.

METHODS

This cross-sectional study involved 309 full-time firefighters aged 20 to 65 years. Cardiovascular health encompassed cardiovascular disease risk factors, risk scores, CVH metrics, and heart rate variability. Musculoskeletal health was assessed using two validated questionnaires.

RESULTS

Increasing age ( P = 0.004), body mass index ( P < 0.001), body fat percentage ( P < 0.001), diastolic blood pressure ( P = 0.003), total cholesterol ( P = 0.006), and Framingham risk score ( P = 0.011) increased the risk of reporting musculoskeletal injuries (MSIs). Obesity ( P = 0.018), hypertension ( P = 0.034), and dyslipidemia ( P = 0.005) increased the risk of reporting MSIs. Musculoskeletal discomfort was associated with total cholesterol ( P = 0.0.34) and low-density lipoprotein ( P = 0.014).

CONCLUSIONS

Adverse cardiovascular disease risk profile was associated with MSIs and musculoskeletal discomfort in firefighters. Firefighters should maintain an ideal CVH profile, especially as they age.

Association between Physical Fitness and Cardiovascular Health in Firefighters

Firefighters perform strenuous work in dangerous and unpredictable environments requiring optimal physical conditioning. The aim of this study was to investigate the association between physical fitness and cardiovascular health (CVH) in firefighters. This cross-sectional study systematically recruited 309 full-time male and female firefighters between the ages of 20 to 65 years in Cape Town, South Africa. Physical fitness was assessed using absolute (abV̇O2max) and relative oxygen consumption (relVO2max), grip and leg strength, push-ups and sit-ups, sit-and-reach for flexibility and lean body mass (LBM). CVH encompassed age, smoking, blood pressure (BP), blood glucose, lipid profile, body mass index, body fat percentage (BF%), and waist circumference. Linear regressions and logistic regressions were applied. Multivariable analysis indicated that relVO2max was associated with systolic BP (p < 0.001), diastolic BP (p < 0.001), non-fasting blood glucose (p < 0.001), and total cholesterol (p = 0.037). Poor CVH index was negatively associated with relV̇O2max (p < 0.001), leg strength (p = 0.019), and push-ups (p = 0.012). Furthermore, age was inversely associated with V̇O2max (p < 0.001), push-up and sit-up capacity (p < 0.001), and sit-and-reach (p < 0.001). BF% was negatively associated with abV̇O2max (p < 0.001), grip and leg strength (p < 0.001), push-ups (p = 0.008), sit-ups (p < 0.001), and LBM (p < 0.001). Cardiorespiratory fitness, muscular strength, and muscular endurance were significantly associated with a better overall CVH profile.

Association between Cardiovascular Disease Risk Factors and Cardiorespiratory Fitness in Firefighters: A Systematic Review and Meta-Analysis

Approximately 45% of on-duty related mortalities were due to sudden cardiac death, with many of these fatalities related to cardiovascular disease and overexertion, while performing emergency duties. Therefore, the aim of this systematic review was to determine the association between cardiovascular disease risk factors and cardiorespiratory fitness in firefighters. A literature search of PubMed, SCOPUS, Web of Science, Embase, EBSCOHost, and ScienceDirect was conducted; the Rayyan® intelligent systematic review tool was used to screen and select studies for inclusion. The appraisal tool for cross-sectional studies and the Critical Appraisal Skills Programme toolkit were used for methodological assessment of included studies. Data were analyzed using the Review Manager 5.3 and MedCalc® statistical softwares to determine the effects of obesity (Z = 10.29, p < 0.001) and aging (Z = 4.72, p < 0.001) on cardiorespiratory fitness. Furthermore, there was a significant effect for cardiorespiratory fitness level on systolic blood pressure (Z = 5.94, p < 0.001), diastolic blood pressure (Z = 2.45, p < 0.001), total cholesterol levels (Z = 3.80, p < 0.001), low-density lipoprotein cholesterol (Z = 4.44, p < 0.001), triglycerides (Z = 3.76, p < 0.001) and blood glucose concentration (Z = 4.78, p < 0.001). Cardiovascular disease risk factors and cardiorespiratory fitness were significantly and inversely associated in firefighters. Fire service departments should adopt behavioral intervention strategies to maintain optimum cardiovascular disease risk factor profiles and cardiorespiratory fitness among firefighters to ensure their occupational well-being.

Relationship between Cardiorespiratory Fitness and Executive Function in Young Adults: Mediating Effects of Gray Matter Volume

We evaluated the association between cardiorespiratory fitness (CRF) and executive function (EF) in young adults and the mediating effects of GMV on this relationship. This study involved 217 college students. An incremental load exercise program was used to evaluate VO2max. EF was estimated by the Flanker task, the 2-back task, and the more-odd shifting task, while structural magnetic resonance and region-based morphometry (RBM) were used to analyze GMV. The high CRF group had a shorter updating reaction time (RT) (p ≤ 0.05). CRF was positively correlated with the right orbital part of the middle frontal gyrus (ORBmid.R) GMV (p ≤ 0.05). ORBmid.R GMV was negatively correlated with updating RT (p ≤ 0.05). Model 4 in SPSS was used to assess the mediating effects of ORBmid.R GMV between CRF and updating RT. ORBmid.R GMV was established to have a partially mediating role between CRF and updating RT, which accounted for 19.6% of the total effect value. These findings indicate that the negative correlation between CRF and EF was significant, and ORBmid.R GMV played a mediating role in the relationship between CRF and EF, providing new evidence toward comprehensively revealing that CRF promotes EF performance.