Virtual Reality Based Active Shooter Training Drill Increases Salivary and Subjective Markers of Stress.

Law enforcement personnel are required to respond to a variety of dangerous, potentially life-threatening high stress scenarios. Virtual reality (VR)-based training has been shown to attenuate stress responses; however, little is known about the acute stress response from VR exposure. This study examined the impact of participating in a VR-based active shooter training drill (ASD) on markers of physiological stress as well as potential differences in men and women. To examine the impact of participation in a ~50 sec VR-based ASD, 29 subjects (n = 29; 17 males, 12 females) participated in a quasi-experimental single group design. Saliva samples were collected and analyzed from 27 of the 29 subjects a total of four times 1) 30-min prior to, 2) 5-min prior to, 3) 5-min after, and 4) 30-min after the ASD and analyzed for α-amylase (AA) activity and concentrations of secretory immunoglobulin-A (SIgA), cortisol (CORT), and uric acid (UA). Participation in the ASD resulted in a significant (p < 0.05) increase in salivary stress markers AA and SIgA. In addition, lower concentrations of CORT and UA were found in women compared to men. These findings have implications for law enforcement and/or military personnel that may seek to implement a VR-based training into their training regimen. Future studies should investigate the impact of longitudinal participation in ASD interventions to determine if this is an effective training method to reduce stress responses to real life active shooter training drills.

Impact of Time Restricted Feeding on Markers of Cardiometabolic Health and Oxidative Stress in Resistance-Trained Firefighters.

ABSTRACT: McAllister, MJ, Gonzalez, AE, and Waldman, HS. Impact of time restricted feeding on markers of cardiometabolic health and oxidative stress in resistance-trained firefighters. J Strength Cond Res 36(9): 2515-2522, 2022-Firefighters are often exposed to numerous occupational stressors that cause inflammation, oxidative stress (OS), and elevated risk for developing cardiometabolic disease. Time-restricted feeding (TRF) has been shown to result in favorable changes in markers of inflammation and cardiometabolic health. This study investigated the impact of a 6-week TRF intervention (14:10; fasting:feeding) in resistance-trained firefighters. Blood was analyzed for several markers of inflammation, OS, and cardiometabolic health: insulin, ghrelin, leptin, glucagon, adiponectin, resistin, advanced glycated end products (AGE), advanced oxidation protein products, total nitrite-nitrate levels, tumor necrosis factor-α, interleukin (IL)-6, IL-8, IL-10, as well as glucose and lipid levels. A graded exercise test was also conducted before and after the TRF intervention, and substrate oxidation rates were calculated and compared before and after the intervention. Comparisons pre and post TRF were determined with dependent t -tests. Time-restricted feeding resulted in significant reductions in advanced oxidation protein products (∼31%) and AGEs (∼25%); however, no other changes were found. These findings suggest that TRF may be a nutrition intervention aimed at improving some select markers of cardiometabolic health in firefighters, namely, by the reductions in advanced oxidation protein products and AGEs.

Predictors of Work Efficiency in Structural Firefighters.

OBJECTIVE: Develop a novel work efficiency (WE) metric to quantify firefighter physical ability and identify correlates of WE. METHODS: Physical fitness and anthropometric measurements were taken on 19 male firefighters. Firefighters performed a timed maximal effort simulated fireground test (SFGT). WE was quantified as: (1/[Air depletion × SFGT completion time]) × 10,000. Regression analyses were used to identify predictors of WE. RESULTS: WE was significantly correlated to age, relative body fat, fat mass, occupational experience, jump height, inverted row repetitions, relative bench press and squat strength, treadmill time to exhaustion, relative ventilatory threshold, and relative peak oxygen consumption. Treadmill time to exhaustion and relative lower body strength accounted for the greatest variance in WE (R2 = 0.72, root mean square error = 0.07). CONCLUSION: Aerobic endurance and relative lower body strength were related to an occupationally-specific assessment of firefighter physical ability.

Time Restricted Feeding Reduces Inflammation and Cortisol Response to a Firegrounds Test in Professional Firefighters.

OBJECTIVE: Firefighters are at a heightened risk for developing cardiovascular disease. The purpose of this study was to determine if time restricted feeding (TRF) can improve the stress/inflammatory response to a simulated firegrounds test (FGT) in professional firefighters. METHODS: Thirteen firefighters participated in an 8-week TRF intervention (14:10 [fasting:feeding]) protocol and completed a FGT before and after the intervention. Blood lactate, heart rate, salivary C-reactive protein (CRP), interleukin-6 (IL-6), interleukin 1-ß (IL-1ß), and cortisol were measured pre and post FGT. RESULTS: Following TRF, the salivary cortisol response to the FGT was significantly (P < 0.05) reduced. Salivary IL-6 and IL-1ß were also significantly lower, and CRP was higher following the intervention. CONCLUSIONS: These findings demonstrate lower inflammation and reduced stress response to FGT following TRF and may suggest implications in terms of cardiometabolic benefits for firefighters.

Impact of Time Restricted Feeding on Fitness Variables in Professional Resistance Trained Firefighters.

Firefighters are at an elevated risk for cardiometabolic disease and sudden cardiac death due to physiological and psychological stressors. Research suggests time restricted feeding (TRF) may improve health and performance variables. OBJECTIVE: This study investigated the effects of a 7-week TRF (14-hour fasting:10-hour eating window) on fitness variables related to physical health and performance among professional, resistance-trained firefighters. METHODS: Several fitness variables were assessed pre- and post-TRF intervention. RESULTS: Relative and absolute ventilatory threshold (VT) increased (P < 0.05), relative and absolute , decreased (P < 0.05), and muscular strength, endurance, and power were not affected pre- versus post-intervention. CONCLUSION: Although , decreased, all other performance variables were not negatively impacted by TRF. Improvements in VT may be associated with improvements to markers of endurance exercise performance in firefighters, but more data are needed to confirm this hypothesis.

Acute coffee ingestion with and without medium-chain triglycerides decreases blood oxidative stress markers and increases ketone levels.

Ingestion of ketone supplements, caffeine, and medium-chain triglycerides (MCTs) may all be effective strategies to increase blood levels of the ketone body beta-hydroxybutyrate (D-BHB). However, acute ingestion of a bolus of lipids may increase oxidative stress (OS). The purpose of the study was to investigate the impact of adding varying amounts of MCTs to coffee on blood levels of D-BHB and markers of OS. Ten college-aged men ingested coffee with 0, 28, and 42 g of MCT in a randomized order. Blood samples were collected pre- as well as 2 and 4 h postprandial and analyzed for D-BHB, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), glucose, triglycerides (TAG), insulin, and OS markers: advanced oxidation protein products (AOPP), glutathione (GSH), malondialdehyde (MDA), and hydrogen peroxide (H2O2). All three treatments resulted in a significant increase in D-BHB, HDL-c, and TC as well as a significant decrease in TAG, MDA, H2O2, and insulin. The 42 g treatment was associated with significantly higher levels of AOPP and MDA. Acute ingestion of coffee results in favorable changes to markers of cardiometabolic health that were not impacted by the addition of 28 g of MCT. However, 42 g of MCT caused significantly greater OS.