Slow Breathing Reduces Markers of Stress in Response to a Virtual-Reality Active Shooter Training Drill

Law enforcement officers are expected to respond to potential life-threatening scenarios in high stress environments. Acute participation in virtual reality (VR) active shooter scenarios has been shown to increase markers of stress. Tactical occupations (i.e., military, law enforcement personnel) are trained to use slow breathing methods to aid in stress reduction, but there is no known evidence supporting the effectiveness of slow breathing in relation to a VR-active shooter training drill (VR-ASD). PURPOSE: To determine the effects of slow breathing on markers of stress in response to a VR-ASD. METHODS: A parallel between subjects design was used, during which, eighty-one (n=81) subjects performed five minutes of either slow breathing method 1 (SB1), slow breathing method 2 (SB2), or no modified breathing [normal breathing (NB)] immediately pre and post VR-ASD. SB1 (i.e., box breathing) involved a four second inhalation, two second pause, four second exhalation, and a two second pause. SB2 involved a four second inhalation, followed by a two second exhalation. The VR-ASD (~1 minute) included a single gunman and simulated victims. Subjects were fitted with a VR headset and equipped with a Glock 17 training pistol. Salivary samples and heart rate (HR) were collected thirty minutes pre, five minutes pre, five minutes post, and thirty minutes post VR-ASD. Saliva was analyzed for stress markers: α-amylase (AA) and secretory immunoglobulin-A (Sig-A). AA and SIgA were analyzed via 3x4 (treatment x timepoint) factorial ANOVAs. HR was analyzed via 2x4 factorial ANOVA. RESULTS: Both methods of slow breathing (SB1 and SB2) resulted in significantly lower AA concentrations at five (p \u3c 0.001), and thirty-minutes post VR-ASD (SB1: p= 0.008; SB2: p \u3c 0.001) compared to NB. In the NB condition, AA concentrations were significantly elevated five minutes post VR-ASD (p \u3c 0.001) compared to all other timepoints but did not change across time in SB1 or SB2 (p \u3e .05). A significant increase in SIgA concentrations was noted five minutes post VR-ASD compared to all the other time points (p \u3c 0.001), and significantly higher SIgA concentrations were found in the NB compared to SB1 and SB2 (p\u3c0.001). Finally, slow breathing resulted in a significant decrease in HR from pre to post VR-ASD (p \u3c 0.05). CONCLUSION: The VR-ASD resulted in a significant increase in stress markers AA and SIgA. Slow breathing (both SB1 and SB2) prevented a significant increase in AA concentrations and resulted in lower concentrations post VR-ASD. Future studies should investigate the effects of longitudinal participation in slow breathing methods on markers of stress in response to a VR-ASD

Impact of Cardiorespiratory Fitness on Markers of Cardiovascular Disease in Professional Firefighters

Higher cardiorespiratory fitness (CRF) levels (V̇O2max) are associated with lower oxidative stress and inflammatory markers in addition to lower cardiovascular disease (CVD) risk; however, there are a lack of data examining this relationship among firefighters. CVD is the leading cause of mortality among firefighters and correlates with low CRF. PURPOSE: To examine differences in markers of CVD risk between firefighters classified as having either high or low levels of CRF. METHODS: Forty-six professional firefighters performed a maximal graded exercise test (GXT; Bruce Protocol), where V̇O2max was estimated from the Foster equation using time to exhaustion. Fasted blood samples were also taken to assess traditional and non-traditional biomarkers of CVD risk: HDL, LDL, glucose, cholesterol, triglycerides, advanced oxidation protein products (AOPP), homeostatic model assessment for insulin resistance (HOMA-IR) and C-reactive protein (CRP). Body fat percentage (BF%) was determined via Dual-Energy X-Ray Absorptiometry (DEXA),V̇O2max values were categorized based on American College of Sports Medicine (ACSM) guidelines to establish a high fitness group (n=19; V̇O2max = 44.7 ± 5.2 ml·kg-1·min-1; age = 35.94 ± 9.73 yrs; height = 178.86 ± 7.28 cm; waist circumference = 35.5 ± 2.73 cm; BF% = 19.9 ± 2.66) and a low fitness group (n=27; V̇O2max = 28.2 ± 4.9ml·kg-1·min-1; age = 38.5 ± 9.33 yrs; height = 179.21 ± 8.48 cm; waist circumference = 40.06 ± 4.29 cm; BF% = 27.2 ± 5.07). Non-parametric Mann-Whitney U tests were used to assess differences in CVD risk markers between the high and low fitness groups. Effect sizes were calculated as Cohen’s d (i.e., small [0.2-0.5], medium [0.5-0.8], large [\u3e 0.8]). RESULTS: Participants classified as high fitness had significantly (p \u3c 0.05) higher V̇O2max and HDL concentrations coupled with significantly lower BF%, cholesterol, triglycerides, LDL, insulin, HOMA-IR, CRP, and AOPP. Half of the observed differences demonstrated a medium effect size (LDL, insulin, HOMA-IR, CRP, and AOPP), while large effect sizes were noted for V̇O2max, BF%, cholesterol, triglycerides, HDL, LDL/HDL risk ratio. CONCLUSION: The high fitness group exhibited lower CVD risk levels and higher HDL levels compared to the low fitness group. Considering the results, firefighters are encouraged to maintain high CRF as well as lower BF% in an effort to reduce the risk of CVD and on-duty cardiac events

Firefighters Versus Law Enforcement Officers: A Comparison Of Cardiovascular Disease Risk

Firefighters (FF) and law enforcement officers (LEO) have heightened cardiovascular disease (CVD) risk due to the stressful nature of their occupations. Data suggest that 45% of on-duty FF fatalities are related to CVD, while LEO have a 1.7 times higher CVD prevalence compared to the general public. To our knowledge, studies comparing FF to LEO, in terms of CVD risk factors, have not been published. This information is necessary to better understand differences in occupational disease risk, as well as to help bridge the gap between stress and CVD markers. PURPOSE: To compare CVD risk biomarkers, fitness, and body composition between career FF and LEO. METHODS: Ninety-eight career, structural male FF (age = 35.1±9.6 yrs; weight = 94.3±15.4 kg; height = 178.4±13.2 cm) and seventy-three career male and female LEO (age = 41.4±9.0 yrs; weight = 92.3±16.8 kg; height = 179.6±8.1 cm) from local fire and police departments were studied. Participants completed a maximal cardiopulmonary exercise test (CPXT), where VO2max was estimated from the Foster equation. Fasted blood samples were collected to assess biomarkers of CVD risk: advanced oxidation protein products (AOPP) and cortisol. Dual-energy X-ray absorptiometry was used to assess body composition and waist and hip measures were taken. Shapiro-Wilk Test was used to assess normality. Independent sample T-tests or non-parametric Mann-Whitney U tests (if normality was violated) were used to assess differences in CVD risk biomarkers, fitness, and body composition between the FF and LEO. Effect sizes were calculated as Cohen’s d (i.e., small [0.2-0.5], medium [0.5-0.8], large [\u3e0.8]). RESULTS: Firefighters had higher (p\u3c0.05) CPXT exercise times (FF: 10.9±1.6 min; LEO: 10.3±2.0 min; d=0.366) compared to LEO. While not statistically significant (p=0.64), FF had higher VO2max values (FF: 38.2±6.6 ml/kg/min; LEO: 36.2±6.2 ml/kg/min; d=0.306). Firefighters also had higher (p\u3c0.05) AOPP (FF: 134.8±90.1 mM; LEO: 106.8±67.6 mM; d=0.342), blood cortisol (FF: 14.2±5.0 mg/dL; LEO: 12.5±5.6 mg/dL; d=0.325), and waist-to-hip ratios (FF: 0.95±0.06; LEO: 0.89±0.08; d=0.792). CONCLUSION: These findings suggest that while FF demonstrated greater CPXT time-to-exhaustion they also expressed greater levels of stress and risk for CVD compared to LEO

Relationship Between Body Fat Distribution and Cardiovascular Disease Risk Biomarkers Among Firefighters

Firefighters are at risk of premature mortality due to cardiovascular disease (CVD). Firefighting is linked to elevations in oxidative stress, inflammation, and stress biomarkers, which all play a role in the development and progression of CVD. High prevalence rates of overweight and obesity have been found among U.S. firefighters. Obesity is considered a CVD risk factor, and firefighters who are classified as overweight or obese have been shown to express lower levels of high-density lipoprotein cholesterol (HDL-C) and higher levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and biomarkers of oxidative stress and inflammation. However, little is known regarding the relationships between fat mass distribution and CVD biomarkers among firefighters. This information can aid the understanding of CVD risk factors among firefighters. PURPOSE: This study examined the relationship between body composition measures and traditional and non-traditional CVD biomarkers among firefighters. METHODS: Ninety-eight career, structural male firefighters (age = 35.1±9.6 yrs; weight = 94.3±15.4 kg; height = 178.4±13.2 cm) from a local fire department were studied. Body composition (i.e., body fat percentage, BF%) was assessed via dual x-ray absorptiometry. Fasted blood samples were analyzed for concentrations of lipids, advanced oxidation protein products (AOPP), and ultra-sensitive C-reactive protein (CRP). Ordinary least square regression analyses were used to assess the relationship between body composition and blood biomarkers. RESULTS: Gynoid fat percentage was inversely predictive (p\u3c0.05) of AOPP, TC, LDL-C, and TG, as well as positively related (p\u3c0.05) to HDL-C, while android fat percentage was positively predictive (p\u3c0.05) of AOPP, CRP, and TG, as well as inversely related (p\u3c0.05) to HDL-C. Increased BF% was positively predictive (p\u3c0.05) of CRP, TC, and LDL-C. CONCLUSION: These findings provide insight into the relationship between body composition and various biomarkers of CVD risk, and may aid future interventions aimed at attenuating CVD risk among firefighters

Predictors of Cardiometabolic Disease Risk Factors in Professional Firefighters

The leading cause of mortality (~50% of deaths) among on-duty firefighters is sudden cardiac death. Firefighters with adequate cardiorespiratory fitness levels (among other muscular fitness metrics) and lower body fat percentage (BF%) are likely to better combat on-duty cardiac events and cardiovascular disease (CVD) risk. Individuals with higher VO2max values may be at lower risk noted by lower oxidative stress and inflammatory biomarkers, which may be more ideal predictors of CVD risk compared to traditional biomarkers (i.e., blood glucose and lipids) among the fire community; however, more research is needed to elucidate. PURPOSE: This study examined the relationship between fitness metrics, body fat percentage, and traditional and non-traditional biomarkers among professional firefighters. METHODS: Ninety-eight professional, male firefighters (age = 36.26 ± 9.08 yrs; height = 179.53 ± 7.06 cm; waist circumference = 37.99 ± 4.13 cm; BF% = 24.39 ± 5.21; years of experience = 11.81 ± 8.00 yrs) from a local fire department were studied VO2max was estimated from total treadmill exercise time using the Foster equation.. Fitness metrics including muscular strength, endurance, and power variables were also measured. Fasted blood samples were analyzed for concentrations of lipids, glucose, insulin resistance (HOMA-IR), advanced oxidation protein products (AOPP), and ultra-sensitive C-reactive protein (CRP). To assess the relationship between fitness metrics and AOPP, CRP, and HOMA-IR, ordinary least square regression analyses were used. RESULTS: VO2max values were inversely (p \u3c 0.05) related to AOPP, HOMA-IR, and CRP. Waist circumference was positively correlated to AOPP concentrations and HOMA-IR, while increased BF% was significantly related to increased CRP concentrations. CONCLUSION: High VO2max values were significantly related to lower AOPP, CRP, and HOMA-IR. Additionally, high waist circumference and BF% values were related to increases in oxidative stress, inflammation, and insulin resistance. Firefighters are encouraged to maintain high cardiorespiratory fitness (VO2max) and lower BF% to reduce CVD and, ultimately, on-duty sudden cardiac death risk

Slow Breathing Reduces Biomarkers of Stress in Response to a Virtual Reality Active Shooter Training Drill

Tactical occupations regularly encounter life-threatening situations while on duty. Although these occupations are often trained to utilize slow breathing (SB) during intense stress, there is no evidence supporting the effects on markers of stress in response to a virtual reality active shooter training drill (VR-ASD). The purpose of the study was to determine the impact of acute SB on biomarkers of stress in response to a VR-ASD. Seventy-nine (n = 79) subjects performed either slow breathing method 1 (SB1), slow breathing method 2 (SB2), or normal breathing (control) for five minutes, both pre- and post-VR-ASD. Saliva samples were analyzed for stress markers, including α-amylase (sAA) and secretory immunoglobulin-A (SIgA). Both methods of SB resulted in significantly lower sAA concentrations at 5 (p p = 0.008; SB2: p p p > 0.05). Thus, both SB1 and SB2 reduced the sAA response and resulted in lower concentrations post-VR-ASD. This study was pre-registered as a clinical trial (“Impact of Breathing Interventions on Stress Markers”; NCT05825846)

Impact of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality based active shooter training drill

Ingestion of L-theanine and L-tyrosine has been shown to reduce salivary stress biomarkers and improve aspects of cognitive performance in response to stress. However, there have been no studies to concurrently examine the impact of both L-theanine and L-tyrosine ingestion during a mental stress challenge (MSC) involving a brief cognitive challenge and a virtual reality based active shooter training drill. Thus, the purpose of this study was to determine the impact of ingestion of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality active shooter drill and cognitive challenge. The cognitive challenge involved a Stroop challenge and mental arithmetic. Eighty subjects (age = 21 ± 2.6 yrs; male = 46; female = 34) were randomly assigned L-tyrosine (n = 28; 2000 mg), L-theanine (n = 25; 200 mg), or placebo (n = 27) prior to MSC exposure. Saliva samples, state-anxiety inventory (SAI) scales, and heart rate (HR) were collected before and after exposure to the MSC. Saliva was analyzed for stress markers α-amylase (sAA) and secretory immunoglobulin A (SIgA). The MSC resulted in significant increases in sAA, SIgA, HR, and SAI. Ingestion of L-theanine and L-tyrosine did not impact markers of stress. However, the L-tyrosine treatment demonstrated significantly lower missed responses compared to the placebo treatment group during the Stroop challenge. These data demonstrate that ingestion of L-theanine or L-tyrosine does not impact markers of stress in response to a MSC but may impact cognitive performance. This study was pre-registered as a clinical trial ("Impact of supplements on stress markers”: NCT05592561)

Impact Of Cardiorespiratory Fitness On Markers Of Cardiovascular Disease Among Law Enforcement Officers

Law enforcement officers (LEOs) have heightened cardiovascular disease (CVD) risk due to the stressful nature of their occupations. The prevalence of CVD among LEOs is 1.7 times higher compared to that of the general public. Higher cardiorespiratory fitness (CRF) levels (VO2max) are associated with lower oxidative stress and inflammatory markers, as well as lower cardiovascular disease (CVD) risk; however, there is a lack of data examining this relationship among law enforcement officers (LEO). PURPOSE: To examine differences in markers of CVD risk between LEOs classified as having either high or low levels of CRF. METHODS: Seventy-three career male and female LEOs completed a maximal cardiopulmonary exercise test (CPXT), where VO2max was estimated from the foster equation. Fasted blood samples were taken to assess traditional and non-traditional CVD risk biomarkers: high-density lipoprotein (HDL), low-density lipoprotein (LDL), glucose, total cholesterol, triglycerides, advanced oxidation protein products (AOPP), cortisol, and C-reactive protein (CRP). Body fat percentage (BF%) was determined via dual-energy X-ray absorptiometry (DEXA), VO2max values were categorized based on American College of Sports Medicine (ACSM) guidelines to establish a high-fitness (HF) group (n=25) and a low fitness (LF) group (n=23). Shapiro-Wilk tests were used to assess normality. Independent sample T-tests or non-parametric Mann-Whitney U tests (if normality was violated) were used to assess differences in CVD risk biomarkers, fitness, and body composition between LEO categorized as HF and LF. Effect sizes were calculated as Cohen’s d (i.e., small [0.2-0.5], medium [0.5-0.8], large [\u3e0.8]). RESULTS: Participants classified as HF had significantly (p2max (HF: 38.5 ml/kg/min; LF: 32.4 ml/kg/min, d=1.30) and CPXT exercise times (HF: 11.05 min; LF: 9.54 min; d=1.28). In addition, the HF group had significantly (p=0.029) higher HDL concentrations (HF: 58.3 mg/dL; LF: 46.9 mg/dL; d=0.65). While not statistically significant (p=0.052), the LF group had greater fat mass compared to the HF group (HF: 48.3 lbs.; LF: 57.4 lbs.; d=-0.576). CONCLUSION: Given the cardioprotective benefits of higher HDL concentrations, these findings support the cardiometabolic benefits of having higher fitness levels among LEOs

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

Objective High cardiorespiratory fitness (CRF) is associated with reduced markers of oxidative stress and cardiovascular disease (CVD) risk factors; however, this relationship has not been elucidated in firefighters. The purpose of this study was to examine differences in markers of CVD risk between firefighters who have either high or low levels of CRF. Methods Forty-six firefighters participated in a maximal graded exercise test and a dual-energy x-ray absorptiometry scan and provided a fasted blood sample. V˙O2max values were categorized based on American College of Sports Medicine guidelines to establish high- and low-fitness groups. Results High fitness firefighters demonstrated significantly higher high-density lipoprotein cholesterol and lower markers of CVD risk: cholesterol, triglycerides, low-density lipoprotein cholesterol, insulin, homeostatic model assessment for insulin resistance, C-reactive protein, and advanced oxidation protein products concentrations. Conclusion Firefighters are encouraged to maintain high CRF to reduce risk of CVD

Risk Factors for Cardiometabolic Disease in Professional Firefighters

Objective Firefighters are plagued with cardiometabolic disease (CMD). Obesity, poor cardiorespiratory and muscular fitness, and blood lipids (low-density lipoprotein cholesterol, triglycerides, low high-density lipoprotein cholesterol) are risk factors for CMD. However, markers of oxidative stress, inflammation, and insulin resistance can provide further insight regarding CMD risk. Methods This study investigated the relationships between fitness metrics (cardiorespiratory and muscular fitness, percent body fat, waist circumference), blood lipids, blood pressure, and years of experience as a firefighter to blood markers of insulin resistance: Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), oxidative stress: advanced oxidation protein products (AOPPs), and inflammation: C-reactive protein. Results Waist circumference and blood concentrations of triglycerides were significantly related to AOPPs and HOMA-IR. Cardiorespiratory fitness was inversely related to AOPPs, HOMA-IR and C-reactive protein. Conclusion These findings demonstrate the importance of high cardiorespiratory fitness and low waist circumference to reduce markers of CMD