Thermoregulatory Demands During Firefighting Activities

The protective barrier of the gear prevents the body from properly cooling itself and the generation of internal body heat and the inability to dissipate heat are further compounded by the weight of the gear.

Most firefighters are on duty for 24 hours, and then they are off for 48 hours and during this time they live at the fire station. Since there is never a "planned emergency," they are always anticipating the alarm. Once the alarm sounds there is an automatic adrenaline "rush" and an increase in their heart rate, before they even get to the fire. Combine the emotional stress of this with the health stresses of being overweight and having low cardiovascular fitness, and the physical stress of fighting the fire, overweight firefighters are more at risk for a heart attack. Interestingly, almost 50% of on-duty firefighter fatalities are not from direct fire related injuries but from heart attack and stroke. A firefighters's aerobic capacity is probably the strongest single determinant of an individual's ability to carry out sustained physical work under hot conditions.

As noted above, early findings of group differences in heat tolerance which were attributed to age are now viewed as manifestations of aerobic capacity and heat acclimatization. In a study conducted by the NFPA from 1977 through 1995, about one-half of all line-of-duty deaths of firefighters were not the result of fires, but heart attacks. In almost all of the cases, the heart attacks suffered by firefighters are directly linked to the exertional demands of the firefighter's job. Nationally, figures show three-fourths of firefighters over the age of 45 who die in the line of duty die from a heart attack. And of the firefighters who have died from a heart attack while in the line of duty, 2 of every 5 had documented heart conditions. Firefighters place considerable strain on the cardiovascular system. Since a fire alarm can come at any time, it's important for firefighters to pre-hydrate the body by drinking six to eight glasses of water per day. The risk of cardiovascular strain can be minimized by being well hydrated, having a high aerobic capacity, and not having excess bodyfat.


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Robbie Durand is an exercise physiologist whom has a undergraduate degree in nutrition and masters degree in exercise physiology. Robbie is actively involved in human physiological responses to exercise and works at the Institute for Exercise and Environmental Medicine in Dallas, TX.