Immediate Load Carriage Improves Core Temperature but Not Skin Temperatures When Wearing Wet Clothing in Mild Cold Air

Abstract

Introduction

Members of the military are regularly exposed to austere environmental conditions that may create clothing saturation in cold conditions. This study sought to determine whether immediate ruck initiation is superior in maintaining rectal temperature (T_re), improving skin temperatures, and augmenting thermal comfort compared with remaining static and/or delayed ruck initiation when wet in cold air.

Methods

Eleven healthy adults (10 males and 1 female, 26±9 y old, 22.5±8.6% body fat) participated in this study. Volunteers were immersed in warm water (34.0±0.3°C) before entering the cold chamber (5.3±0.4°C) and began immediately rucking (IR) or stood statically for 60 min (Static) before rucking (delayed rucking [DR]) for 60 min.

Results

IR initiation was superior in elevating T_re compared with Static at 20 min (37.6±0.4 vs 37.3±0.2°C, P=0.033), 40 min (37.9±0.4 vs 37.5±0.2°C, P=0.012), and 60 min (37.9±0.4 vs 37.6±0.3°C, P=0.016). IR T_re was also greater than DR at 40 min (37.9±0.4 vs 37.4±0.5°C, P=0.002) and 60 min of wet-cold exposure (37.9±0.4 vs 37.5±0.5°C, P<0.001). Consequently, IR tended to improve thermal sensation ratings compared with both DR and Static. Yet, IR was no more sufficient in overcoming wet-cold decrements in skin temperatures than Static, especially at the finger (P>0.05).

Conclusions

Compared with DR and Static, IR is effective at elevating deep body temperature and improving thermal perceptions but is significantly less effective at improving wet-cold skin temperatures compared with Static.