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Effectiveness of Ice-Vest Cooling in Prolonging Work Tolerance Time during Heavy Exercise in the Heat for Personnel Wearing Canadian Forces Chemical Defence Ensembles
DEFENCE AND CIVIL INST OF ENVIRONMENTALMEDICINE DOWNSVIEW (ONTARIO)
Pagination or Media Count:
Effectiveness of a portable, ice-pack cooling vest Steelevest in prolonging work tolerance time in chemical defense clothing in the heat 33 C dry bulb, 33 relative humidity or 25 C WBGT was evaluated while subjects exercised at a metabolic rate of approx. 700 watts. Subjects were six male volunteers. The protocol consisted of a 20 minute treadmill walk at 1.33 ms. and 7.5 grade, followed by 15 minutes of a lifting task, 5 minutes rest, then another 20 minutes of lifting task for a total of one hour. The lifting task consisted of lifting a 20 kg box, carrying task for a total of one hour. The lifting task consisted of lofting a 20 kg box, carrying it 3 metres and setting it down. This was followed by a 6 m walk 3m back to the start point and 3 m back to the box in 15 sec after which the lifting cycle began again. The work was classified as heavy as previously defined. This protocol was reapted until the subjects were unable to continue or they reached a physiological endpoint. Time to voluntary cessation or physiological endpoint was called the work tolerance time. Physiological endpoints were rectal temperature of 39 C, heart rate exceeding 95 of maximum for two consecutive minutes of visible loss of motor control or nausea. The cooling vest had no effect on work tolerance time, rate of rise of rectal temperature or sweat loss. It was concluded that the Steelvest ice-vest is ineffective in prolonging work tolerance time and preventing increases in rectal temperature while wearing chemical protective clothing.
APPROVED FOR PUBLIC RELEASE