Biomarkers of mild hyperthermia related to flashover training in firefighters

Evaluation of a Wearable Non-Invasive Thermometer for Monitoring Ear Canal Temperature during Physically Demanding (Outdoor) Work

Aimed at preventing heat strain, health problems, and absenteeism among workers with physically demanding occupations, a continuous, accurate, non-invasive measuring system may help such workers monitor their body (core) temperature. The aim of this study is to evaluate the accuracy and explore the usability of the wearable non-invasive Cosinuss° °Temp thermometer. Ear canal temperature was monitored in 49 workers in real-life working conditions. After individual correction, the results of the laboratory and field study revealed high correlations compared to ear canal infrared thermometry for hospital use. After performance of the real-life working tasks, this correlation was found to be moderate. It was also observed that the ambient environmental outdoor conditions and personal protective clothing influenced the accuracy and resulted in unrealistic ear canal temperature outliers. It was found that the Cosinuss° °Temp thermometer did not result in significant interference during work. Therefore, it was concluded that, without a correction factor, the Cosinuss° °Temp thermometer is inaccurate. Nevertheless, with a correction factor, the reliability of this wearable ear canal thermometer was confirmed at rest, but not in outdoor working conditions or while wearing a helmet or hearing protection equipment.

Exercise in a hot environment influences plasma anti-inflammatory and antioxidant status in well-trained athletes

Exercise in thermally stressful environmental conditions can enhance oxidative stress. We sought to measure the plasma antioxidant defenses and cytokine response together with oxidative damage post-exercise in a temperate versus a hot environment. The plasma concentrations of vasoactive endothelin-1 and vascular angiogenic growth factor were also evaluated. Male athletes (n=9) volunteered to participate. The athletes randomly performed two bouts of treadmill exercise of 45min at 75-80% of maximal oxygen uptake in a climatic-controlled chamber under two different conditions: temperate environment (10-12°C, 40-55% humidity) and hot, humid environment (30-32°C, 75-78% humidity). Venous blood samples were obtained immediately pre- and post-bout and on recovery after 2h. Serum glucose, malondialdehyde and lactate concentrations were significantly increased post-exercise in hot but maintained in the temperate environment; these post-exercise values were significantly higher after exercise in hot than in temperate. Urinary 8-hydroxy-2'-deoxyguanosine concentration, plasma phosphocreatine kinase and catalase activities, creatinine and monocyte chemoattractant protein-1, and interleukin-6 significantly increased post-exercise in hot but maintained in temperate environment. The post-exercise circulating values of antioxidant enzyme paraoxonase-1 and endothelin were significantly higher in the hot than in temperate environment. Exercise in a hot and humid environment resulted in mild hyperthermia with elevated perceived exertion and thermal stress. Hyperthermic environment induced hyperglycemia, lactatecidemia and more cellular and oxidative damage than exercise in a temperate environment but also induced a post-exercise antioxidant and anti-inflammatory response in plasma. These results suggest that environmental temperature needs to be taken into account when evaluating exercise-related oxidative stress and inflammation.

Response to thermal and physical strain during flashover training in Croatian firefighters

Flashover training (FOT) for firefighters is a simulation of the flashover phenomenon under controlled conditions. This study assessed arterial blood pressure (BP) and its response to thermal and physical strain during FOT in 48 professional and 18 volunteer firefighters. A high prevalence of obesity (27%), basal hypertensive (53%) and prehypertensive (33%) BP values was found. FOT induced mild hyperthermia and physical strain (average increase of 1.1 °C in tympanic temperature and 61% of the maximal heart beat predicted for age). Compared to professional firefighters, FOT in the volunteers induced a higher increase in pulse (P = 0.050) and tympanic temperature (P = 0.025). Systolic BP did not vary significantly, and diastolic BP slightly decreased in both groups. Results confirm that FOT induced only physiological cardiovascular responses to thermal and physical strain in firefighters. High prevalence of obesity and elevated BP values indicate the need for better physical fitness and BP control among firefighters.