Whole-body active heating does not preserve finger temperature or manual dexterity during cold-water immersion

Abstract

Background: Cold-water immersion impairs manual dexterity when finger temperature is below 15˚C. This exposes divers to increased risk of error. We hypothesized that whole-body active heating would maintain finger temperatures and dexterity during cold-water immersion. Methods: Twelve subjects (six males) (22±2 years old; BMI 23.9±2.5; body fat 16±6%) completed 60-minute head-out water immersion (HOWI) wearing a 7mm wetsuit and 3mm gloves in thermoneutral water (TN 25˚C) and cold water (CW 10˚C)while wearing a water-perfused suit (WP) with 37˚C water circulated over the torso, arms, and legs. Gross (Minnesota Manual Dexterity Test [MMDT]) and fine (modified Purdue Pegboard [PPT]) dexterity were assessed before, during and after immersion. Core body and skin temperatures were recorded every 10 minutes. Results: MMDT (TN -25±14%; CW -72±23%; WP -67±29%; p<0.05) and PPT (TN -16±9%; CW: -45±10%; WP: -38±13%; p<0.05) performance decreased during immersion. MMDT and PPT did not differ between CW and WP. Immediately following immersion gross dexterity was recovered in all conditions. Post-immersion fine dexterity was still impaired in CW (p<0.01), but not WP or TN. Core and skin temperatures decreased during immersion in CW and WP (p<0.05) but did not differ between CW and WP. Conclusions: Manual dexterity decreased during immersion. Dexterity was further impaired during cold-water immersion and was not maintained by water perfusion active heating. Warm water perfusion did not maintain finger temperature above 15˚C but hand temperature remained above these limits, suggesting a need to reassess thermal thresholds for working divers in cold-water conditions.

Comparison of insulation provided by dry or wetsuits among recreational divers during cold water immersion (< 5°C)

“…This can be achieved either by insulation or by using some heating device, but both seem to be ineffective. Indeed, according to previous literature, neither manual dexterity nor finger temperature could be rescued using whole body active heating [21], while in wet-suited subjects, wearing gloves and boots seems to increase the overall rate of body heat loss [8,33]. Consistently with these findings, no difference in hand's temperature among groups was observed and pain in the hands with major discomfort was the main complaint in both groups at the end of the dive.…”

“…Consequently, comfort and dexterity may be the limiting factor in performance/endurance irrespective of how well the rest of the body is protected. It is indeed a known fact that manual gross and fine dexterity decreases by 71.6 ± ± 22.9% and 44.5%, respectively during cold water (10°C) immersion and continue to decrease with immersion time [21].…”

“…Also, from the physiological standpoint, this might not be adapted as we are more interested on how the divers' thermal balance to cold exposure is modified by any type of diving suit rather than the insulation per se. Then, alternative means would be to measure skin temperature at multiple sites as body heat loss will depend on the heat flux from different sites [21]. Although, these thermocouples are non-invasive, the required hard-wired connections to a datalogger limit its validity and fail to address questions and applications outside the laboratory.…”