Cardiovascular responses to five cooling strategies wearing a prototype firefighter ensemble.
Coca-A; Roberge-RJ; Powell-JB; Kim-J-H; Williams-WJ
Med Sci Sports Exerc 2010 May; 42(5)(Suppl 1):767-768
Overexertion/stress is among the most common causes of injuries and deaths amongst firefighters. The stress faced by a firefighter results from a myriad of sources, including the work environment, and their protective equipment. PURPOSE: The purpose of this study was to evaluate five cooling strategies based on exploiting the conductive/convective mechanisms of body cooling. Our hypothesis was that any cooling (garments and/or ventilation) would provide less cardiovascular stress to the wearer thus reducing heart rate (HR), sweat loss (SL), and skin and rectal temperatures (Tsk and Tre). METHODS: Six male subjects participated in this study. Each subject completed six exercise sessions using the same prototype firefighter ensemble (PFE) under random conditions with five different cooling sessions and one control session without cooling (CS). The five cooling sessions were conducted wearing various cooling strategies, as follows: 1) a whole body cooling garment (CG); 2) CG plus air ventilation (AV) from the PFE hose (CG+AV); 3) a top cooling garment (TCG); 4) TCG plus AV (TCG+AV); 5) only AV. Each session consisted of 3 stages of 15 min exercise on a treadmill at 75% VO2max with 10 min rest between stages while Tre, Tsk and heart rate (HR) were measured. Nude weight to calculate SL was measured prior and after each session. Each session was completed in an environmental chamber operating at 35 degrees C and 50% RH. RESULTS: Results from this study showed that HR, Tsk and Tre were lower for CG and CG+AV than for CS (p<= 0.05). Sweat loss was higher for CS than for CG (p<= 0.05). CONCLUSION: The results of this research suggest that a whole body cooling garment (CG) with or without the additional ventilation system (AV) can be helpful in reducing cardiovascular stress and the risk of heat-related injuries. In addition, air ventilation (convective heat loss) through the hose seems to augment the effect of the cooling garments to reduce HR, Tsk and Tre, therefore decreasing cardiovascular and thermal stress. However, the hose system used for convective heat loss in this PFE does not show any improvement by itself.
Biological-factors; Body-protection; Body-temperature; Cardiopulmonary-system; Cardiovascular-function; Cardiovascular-function-tests; Cardiovascular-system; Clothing; Comfort-zones; Exposure-levels; Fire-fighters; Fire-protection-equipment; Heat-acclimatization; Heat-conduction; Heat-exposure; Heat-regulation; Heat-tolerance; Laboratory-testing; Physical-reactions; Physical-stress; Physiological-effects; Physiological-factors; Physiological-measurements; Physiological-response; Physiological-testing; Quantitative-analysis; Statistical-analysis
Aitor Coca, National Institute of Occupational Safety and Health, NPPTL, Pittsburgh, PA
Medicine and Science in Sports and Exercise