Physiological Responses to Simulated Approach March in Desert and Tropic Conditions: Effects of Three Microclimate Cooling Configurations.

摘要

This study supported the U.S. Army Natick Soldier Research, Development, and Engineering Center (NSRDEC) effort to develop lightweight microclimate cooling systems (MCCS) for use by dismounted Soldiers by evaluating the cooling potentials of two prototype MCCS. This development is underway because it is known that military operations in warm and hot environments that require wearing helmets and body armor in addition to carrying the added weight of mission essential equipment pose a thermoregulatory challenge to Soldiers. For dismounted troops, load carriage of the cooling system imposes an additional metabolic burden and spatial configuration challenge. While HAZMAT and explosive ordnance disposal troops currently have MCCS available to them, it may be possible to extend the application for more dismounted troops by using a smaller capacity MCCS that reduces load carriage, or by using a vehicle-mounted MCCS only during rest periods. This study evaluated two liquid vapor compression systems in which the components differed in size, weight, and cooling capacity. One system (LO) was 93 cubic inches, and weighed 4.2 kg, with a cooling capacity of 120 W. The other system (HI) was 200 cubic inches, and weighed 6.5 kg with a cooling capacity of 250 W. The nominal 120 W of cooling and 250 W of cooling were each used continuously to reduce heat strain in volunteers exercising in desert (45 deg C Tdb, 20% rh) and tropic (35 deg C Tdb, 70% rh) environments while dressed and equipped for an approach march with approximately 33kg of clothing and equipment. A third experimental test (INT) was conducted using 250 W of cooling delivered intermittently only during rest periods. On this test, no cooling was delivered during exercise; however, the cooling vest was worn. A control test (NC) was also performed in each environment with no cooling provided at any time. On this test the volunteer wore neither the cooling vest nor the MCCS.