Effect of localized microclimate heating on peripheral skin temperatures and manual dexterity during cold exposure

Abstract

Reduced dexterity (DEX) is a problem in cold weather with a need for countermeasures that increase hand (T) and finger (T) temperatures and improve DEX. The purpose of the study was to determine whether heat applied to the forearm (ARM), face (FACE) or both (COMB) at the beginning of cold exposure (COLD; 0.5°C, 120-min) or after T fell to 10.5°C (delayed trials, D) improves temperatures and DEX. Eight volunteers (26±9 yr) completed 7 COLD trials: ARM, ARM-D, FACE, FACE-D, COMB, COMB-D, and no heating (CON). Temperatures and DEX were measured before (BASE) and during COLD. Data are reported for min 90. Thand was warmer (p<0.001) during ARM (18.0±2.6°C) and COMB (18.9±2.0°C) vs. CON (15.3±1.5) and FACE (15.8±1.5°C) for heating that was initiated at the beginning of COLD. T was higher (p<0.04) during COMB (12.7±5.1°C) vs. CON (9.7±2.1°C) and FACE (8.9±2.2°C). The change from BASE for Purdue pegboard assembly (# of pieces) was less (p<0.005) in COMB (-4.5±3.3) and ARM (-5.0±6.0) vs. CON (-13.0±7.3) and FACE (-10.0±8.3). There was no change in finger key pinch strength from BASE to min-90 in ARM or COMB, but decreased by 20% in CON and FACE. There were no differences in T, T, and DEX when comparing heating that was initiated at the beginning of COLD vs. delayed heating. In conclusion, forearm heating improved Thand and T and reduced the decline in DEX by 20-50% and finger strength by 90%. Delayed heating had no deleterious effect on temperatures and hand function.

Development of interactive guidance for cold exposure using a thermoregulatory model

“…CoWEDA was validated with physiological data from three studies: 1) eight volunteers sat in 0.5°C for 2 h and wore 3 layers of the Army Extended Cold Weather Clothing System (ECWCS) on torso and 2 layers on legs but were bare-handed throughout the exposures [ 29 ]; 2) six volunteers rested or exercised at two intensities in 0, −20 and −30°C environments for up to 2 h, and they wore an ECWCS ensemble and three different gloves [ 30 ]; 3) four volunteers wore the ECWCS ensemble and were exposed to −40°C environments for 2 h [ 31 ].…”

We are all exposed, but some are more exposed than others

“…Performance degradation of the extremities is usually expressed by dexterity loss. Dexterity can further be classified into gross (e.g., loosening of nuts) and fine dexterity (e.g., inserting pins) and is generally found to decrease when hand skin temperature reaches below 22°C and becomes critical below 15°C [ 2 , 16–18 ]. Furthermore, non-freezing CWI can develop when skin temperature is maintained below 15°C for long durations, and general risk for CWI is expected when skin temperatures are below 5 °C for long durations [ 1 , 19 ].…”

Environmental Stress in Military Settings

“…One of the major human performance concerns when operating in the cold is the loss of manual dexterity, which declines precipitously once hand and finger temperatures fall below ~15 C (Schiefer et al 1984), causing the largest effect on tasks requiring fine finger dexterity (Castellani et al 2018). From an operational perspective, having cold fingers may negatively impact the activities required to keep a mission on track (like equipment repairs or medical procedures) and one's ability to handle weapons.…”

“…Strategies center on the behavioral responses listed above, as well as keeping clothing dry. Skin-heating devices increase peripheral blood flow and slow the decline in skin temperature (Castellani et al 2018) but have not been widely implemented in the field.…”