Introduction: The aim of this study was to evaluate how the textile composition of torso undergarment fabrics may impact upon thermal strain, moisture transfer, and the thermal and clothing comfort of fully clothed, armored individuals working in a hot-dry environment (41.2 degrees C and 29.8% relative humidity).
Methods: Five undergarment configurations were assessed using eight men who walked for 120 min (4 km x h(-1)), then alternated running (2 min at 10 km x h(-1)) and walking (2 min at 4 km x h(-1)) for 20 min. Trials differed only in the torso undergarments worn: no t-shirt (Ensemble A); 100% cotton t-shirt (Ensemble B); 100% woolen t-shirt (Ensemble C); synthetic t-shirt (Ensemble D: nylon, polyethylene, elastane); hybrid shirt (Ensemble E).
Results: Thermal and cardiovascular strain progressively increased throughout each trial, with the average terminal core temperature being 38.5 degrees C and heart rate peaking at 170 bpm across all trials. However, no significant between-trial separations were evident for core or mean skin temperatures, or for heart rate, sweat production, evaporation, the within-ensemble water vapor pressures, or for thermal or clothing discomfort.
Conclusion: Thus, under these conditions, neither the t-shirt textile compositions, nor the presence or absence of an undergarment, offered any significant thermal, central cardiac, or comfort advantages. Furthermore, there was no evidence that any of these fabrics created a significantly drier microclimate next to the skin.