2007, Piran, Slovenia

Acute and chronic heat exposure
EFFECT OF A PERSONAL COOLING SYSTEM ON PHYSIOLOGICAL
STRAIN DURING HEAT STRESS IN REST AND EXERCISE
Amir Hadid, Ran Yanovich, Tomer Erlich, Gennadi Khomenok, Osnat Ron-Tal,
Daniel S. Moran
Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer and the Sackler
Faculty of Medicine, Tel Aviv University, ISRAEL
Contact person: dmoran@sheba.health.gov.il
INTRODUCTION
Under the conditions of exercise heat stress or rest in hot environments, the ability to maintain
body temperature within physiological limits is hampered, particularly when ballistic
protective garments are worn. Thus, auxiliary cooling methods are needed to alleviate heat
stress. The present study was conducted to evaluate whether physiological strain is alleviated
by a new personal Cooling System (CS), which consists of a layered vest and integrated
blower that generate low-pressure flow of air over the torso skin. In this study, volunteers
wore the CS under a protective garment and rested and exercised under a heavy heat load.
METHODS
Twelve young, healthy, male volunteers participated in this study. All participants were
exposed to climatic conditions of 40°C, 40% RH (40/40), and 35°C, 60% RH (35/60) during
which they performed a 185 min exercise routine while wearing a battle dress uniform (BDU)
and ballistic vest. The routine included 5 min of sitting followed by two bouts of 50 min
walking on a treadmill (5 km·hr -1 , 2% grade) separated by 10 min of rest, followed by another
60 min of sitting. All the test subjects were exposed to these experimental conditions with and
without the CS worn under their BDU. During the exposures, the volunteers' body core
temperature (Trec), skin temperature (Tsk), and heart rate (fc) were continuously monitored.
Sweat rate heat storage were calculated for each exercise routine.
RESULTS
The results demonstrate that the CS was able to significantly attenuate the physiological strain
levels during exercise under the prescribed conditions, when compared to identical exercise
exposure without the CS. When used in 40/40 and 35/60, the CS reduced rectal temperature
elevation rate, ∆Trec (Trec t -Trec 0 ), by 0.26 ±0.20 o C and 0.34 ±0.21 o C, respectively, after 115
min of exercise (p