Psychophysiological responses of firefighters to day and night rescue interventions

Physiological demands and physical performance determinants of a new firefighting simulation test

The study aimed to examine physiological responses of firefighters performing a firefighting simulation test (FST) and to determine the relationship between physical fitness parameters and FST performance. Aerobic fitness, muscular strength, muscular endurance, and anaerobic capabilities were evaluated in 37 firefighters (21-profesionals and 16-volunteers firefighters). Furthermore, participants carried out the FST during which we measured performance, respiratory gas exchange, heart rate (HR), perceived exertion and blood lactate concentrations. Males were significantly faster than females for all tasks of the FST (p < 0.01); however, final performance score (16.5 ± 2.9 and 14.5 ± 2.6 points for males and females, respectively), HR (94.0 ± 2.0% and 93.7 ± 2.3% of HRmax) and perceived exertion (8.1 ± 0.9 and 7.1 ± 1.3) were not significantly different. Prediction of FST performance by LASSO regression revealed a model that included mainly aerobic capacity and maximal strength. In conclusion, FST challenged both aerobic and anaerobic energy metabolisms for both males and females and requires various physiological abilities to perform. Practitioner Summary: For the safety of firefighters and victims, firefighters must meet minimum physical requirements. 37 firefighters performed physical tests and a new firefighting test implemented for the recruitment of firefighters in France. The results revealed that this test is strenuous and that performance is associated with cardiorespiratory fitness and muscular strength. Abbreviations: V̇O2: oxygen consumption; V̇CO2: carbon dioxyde production; V̇E: expired ventilation; RER: respiratory exchange ratio; FST: firefighting simulation test; MAS: maximal aerobic speed; HR: heart rate; RPE: rating of perceived exertion; MVC: maximum voluntary contraction; IMTP: isometric mid-thigh pull; TTE: time to exhaustion; Ppeak: peak power; Pmean: mean power; LASSO: least absolute shrinkage and selection operator; La-: blood lactate concentration.

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.

Autonomic Nervous System Response to Far-Infrared Sauna Exposure in Firefighters

OBJECTIVES

Fire departments have employed far-infrared sauna (FIRS) use as part of post-fire call protocols to address concerns related to carcinogens. The inability of the autonomic nervous system (ANS) to fully recover following an emergency call, as demonstrated by heightened sympathetic nervous system activity and delayed parasympathetic nervous system reactivation, has been implicated as a potential factor related to sudden cardiac death. The use of a sauna post-fire call, which has been demonstrated to elevate body temperature, may interfere with the ability of the ANS to fully recover. The purpose of this study was to examine ANS responses to FIRS exposure in firefighters (FFs) with (EX) and without (NONEX) prior maximal exercise.

METHODS

Sixteen career FFs participated in this study. Body temperature (TEMP), heart rate (HR), heart rate variability (HRV), blood pressure (BP), and blood lactate (La─) were measured at the start of each testing session, following a maximal exercise test (EX only), and immediately after a 15-min FIRS exposure for NONEX and EX.

RESULTS

In NONEX, TEMP increased (P < 0.001); however, there was no change in HR, HRV, BP, or La─. In EX, BP remained unchanged while TEMP, HR, and La─ were significantly (P < 0.001) greater than baseline following FIRS exposure and HRV was significantly (P = 0.018) lower than baseline.

CONCLUSIONS

These findings indicate that FIRS following maximal exercise did support some ANS recovery, but may interfere with restoration of body temperature and parasympathetic nervous system reactivation, potentially influencing post-call cardiovascular risk in FFs.