Luiz Guilherme G. Porto

Body Composition is Strongly Associated With Cardiorespiratory Fitness in a Large Brazilian Military Firefighter Cohort: The Brazilian Firefighters Study.

Abstract Nogueira, EC, Porto, LGG, Nogueira, RM, Martins, WR, Fonseca, RMC, Lunardi, CC, and de Oliveira, RJ. Body composition is strongly associated with cardiorespiratory fitness in a large Brazilian military firefighter cohort: The Brazilian Firefighters Study. J Strength Cond Res 30(1): 33–38, 2016—Firefighting is associated with high-level physical demands and requires appropriate physical fitness. Considering that obesity has been correlated with decreased cardiorespiratory fitness (CRF) and that the prevalence of obesity may also be elevated within firefighters (FF), we analyzed the association between CRF and body composition (BC) in Brazilian military FF. We assessed 4,237 male FF (18–49 years) who performed a physical fitness test that included BC and CRF. Body composition was assessed by body mass index (BMI), body adiposity index (BAI), body fat percentage (BF%), and waist circumference (WC). CRF was assessed by the 12-minute Cooper test. Comparisons of V[Combining Dot Above]O2max between the BC categories were analyzed using the Mann-Whitney test, and the analysis was adjusted for age using the General Linear Model. The Spearman test was used for correlation analysis and the odds ratio (OR) was calculated to assess the odds of the unfit group (⩽12 metabolic equivalents [METs]) for poor BC. Statistically significant differences were considered when p ⩽ 0.05. Considering the BMI categories, 8 volunteers (0.2%) were underweight, 1,306 (30.8%) were normal weight, 2,301 (54.3%) were overweight, and 622 (14.7%) were obese. The V[Combining Dot Above]O2max was negatively correlated with age (r s = −0.21), BMI (r s = −0.45), WC (r s = −0.50), and BAI (r s = −0.35) (p < 0.001). Cardiorespiratory fitness was lower in the obese compared with the nonobese for all age categories (−3.8 ml·kg−1·min−1; p < 0.001) and for all BC indices (−4.5 ml·kg−1·min−1; p < 0.001). The OR of the unfit group having poor BC in all indices varied from 2.9 to 8.1 (p < 0.001). Despite the metabolically healthy obesity phenomenon, we found a strong association between CRF and BC irrespective of age and the BC method (BMI, BAI, WC, or BF%). These findings may aid in improving FF training programs with a focus on health and performance.

Effect of Body Mass Index on Left Ventricular Mass in Career Male Firefighters

Left ventricular (LV) mass is a strong predictor of cardiovascular disease (CVD) events; increased LV mass is common among US firefighters and plays a major role in firefighter sudden cardiac death. We aim to identify significant predictors of LV mass among firefighters. Cross-sectional study of 400 career male firefighters selected by an enriched randomization strategy. Weighted analyses were performed based on the total number of risk factors per subject with inverse probability weighting. LV mass was assessed by echocardiography (ECHO) and cardiac magnetic resonance, and normalized (indexed) for height. CVD risk parameters included vital signs at rest, body mass index (BMI)–defined obesity, obstructive sleep apnea risk, low cardiorespiratory fitness, and physical activity. Linear regression models were performed. In multivariate analyses, BMI was the only consistent significant independent predictor of LV mass indexes (all, p <0.001). A 1-unit decrease in BMI was associated with 1-unit (g/m1.7) reduction of LV mass/height1.7 after adjustment for age, obstructive sleep apnea risk, and cardiorespiratory fitness. In conclusion, after height-indexing ECHO-measured and cardiac magnetic resonance–measured LV mass, BMI was found to be a major driver of LV mass among firefighters. Our findings taken together with previous research suggest that reducing obesity will improve CVD risk profiles and decrease on-duty CVD and sudden cardiac death events in the fire service. Our results may also support targeted noninvasive screening for LV hypertrophy with ECHO among obese firefighters.

Agreement between BMI and body fat obesity definitions in a physically active population

Objectives Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physically active population. Subjects and methods 3,822 military firefighters underwent a physical fitness evaluation including cardiorespiratory fitness (CRF) by the 12 min-Cooper test, abdominal strength by sit-up test (SUT) and body composition (BC) by BF% (as the reference), as well as BMI. Obesity was defined by BF% > 25% and BMI ≥ 30 kg/m2. Agreement was evaluated by sensitivity and specificity of BMI, positive and negative predictive values (PPV/NPV), positive and negative likelihood (LR+/LR-), receiver operating characteristic (ROC) curves and also across age, CRF and SUT subgroups. Results The prevalence of obesity estimated by BMI (13.3%) was similar to BF% (15.9%). Overall agreement was high (85.8%) and varied in different subgroups (75.3-94.5%). BMI underestimated the prevalence of obesity in all categories with high specificity (≥ 81.2%) and low sensitivity (≤ 67.0). All indices were affected by CRF, age and SUT, with better sensitivity, NPV and LR- in the less fit and older groups; and higher specificity, PPV and LR+ among the fittest and youngest groups. ROC curves showed high area under the curve (≥ 0.77) except for subjects with CRF ≥ 14 METs (= 0.46). Conclusion Both measures yielded similar obesity prevalences, with high agreement. BMI did not overestimate obesity prevalence. BMI ≥ 30 was highly specific to exclude obesity. Because of systematic under estimation, a lower BMI cut-off point might be considered in this population.

Cardiac Enlargement in US Firefighters: Prevalence Estimates by Echocardiography, Cardiac Magnetic Resonance and Autopsies

Background: Cardiovascular Disease (CVD) accounts for 45% of on-duty deaths in US fire service; cardiac enlargement is common among US firefighters; and plays a major role in firefighter Sudden Cardiac Death (SCD). Objective: To estimate the prevalence of cardiac enlargement in US Firefighters by autopsies, echocardiography (ECHO) and Cardiac Magnetic Resonance (CMR). Methods: In the present cross-sectional study, the prevalence of Left Ventricular Hypertrophy (LVH)/ cardiomegaly was a) estimated non-invasively among active career firefighters and b) examined by reviewing autopsies of firefighters who suffered a non-cardiac, on-duty fatality. Left ventricular mass (LVM) among active career firefighters was assessed by ECHO and CMR, and normalized (indexed) for body surface area (BSA) and height. Autopsy estimates were based on cardiac weights and other forensic parameters. Results: LVH prevalence estimates among active career firefighters presented a range from 3.3% to 32.8% among ECHO; and 0.0% to 5.3% among CMR criteria. LVH was present in 17.5% and 0.4% of the active firefighters as defined by LVM indexed to height 1.7 (by ECHO and CMR, respectively). LVM indexed to BSA as measured by CMR indicated zero prevalence of LVH. Among non-cardiac traumatic autopsies, prevalence estimates of cardiomegaly and LVH were 39.5% (95% CI 33.7–45.3) and 45.4% (95% CI 39.5–51.4) respectively, even after adjustment for age and BMI. Conclusions: The prevalence of cardiac enlargement varied widely depending on the imaging assessment, the cutoffs and the normalization techniques. For autopsy data, BMI was a major determinant of heart weight. Future CVD-outcome based studies are needed to provide evidence for the most accurate clinical cutoffs, while standardization of autopsies is needed across protocols and jurisdictions.

Physical Fitness and Heart Rate During Exercise Testing as Predictors of Cardiac Autonomic Impairment among Firefighters: 2271 Board #2 June 2, 3: 15 PM - 5: 15 PM.

Cardiac autonomic impairment (CAI) as characterized by a sympathetic hyperactivity and/or a reduced parasympathetic activity is associated with sudden cardiac death.PURPOSE: To estimate CAI prevalence among firefighters and its association with physical fitness and heart rate (HR) profile using exer