Continuous and intermittent personal microclimate cooling strategies

Area of Science:

• Environmental Physiology
• Human Performance
• Protective Clothing Technology

Background:

• Wearing the USAF Chemical Defense Ensemble (CDE) can induce significant thermal stress during physical exertion.
• Personal auxiliary cooling systems are explored to mitigate heat strain in protective ensembles.

Purpose of the Study:

• To compare the effectiveness of two personal microclimate air cooling methods against a no-cooling control.
• To evaluate cooling strategies for personnel wearing the CDE in warm and hot environments.

Main Methods:

• Subjects performed intermittent exercise at 40% VO2max in warm (28/24/34°C) and hot (38/26/43°C) conditions.
• Two cooling methods were tested: intermittent cooling (IC) during rest and continuous cooling (CC) during work and rest.
• Physiological (rectal temperature, heart rate, sweat production) and subjective (RPE, thermal comfort) measures were recorded.

Main Results:

• Both CC and IC significantly reduced thermal stress compared to no cooling (NC).
• CC demonstrated superior results over IC, showing lower sweat production, higher sweat evaporation, and improved thermal comfort and perceived exertion.
• CC also enhanced the ability to maintain thermal equilibrium over time in warm conditions.

Conclusions:

• Continuous personal microclimate air cooling is a highly effective strategy for managing thermal stress in the CDE.
• Personal cooling systems can significantly improve wearer tolerance and performance in demanding thermal environments.
• Subjective improvements in thermal comfort and perceived exertion are critical outcomes of effective cooling strategies.