Influence of body heat content on hand function during prolonged cold exposures

Abstract

We examined the influence of 1) prior increase [preheating (PHT)], 2) increase throughout [heating (HT)], and 3) no increase [control (Con)] of body heat content (H(b)) on neuromuscular function and manual dexterity of the hands during a 130-min exposure to -20 degrees C (coldEx). Ten volunteers randomly underwent three passive coldEx, incorporating a 10-min moderate-exercise period at the 65th min while wearing a liquid conditioning garment (LCG) and military arctic clothing. In PHT, 50 degrees C water was circulated in the LCG before coldEx until core temperature was increased by 0.5 degrees C. In HT, participants regulated the inlet LCG water temperature throughout coldEx to subjective comfort, while the LCG was not operating in Con. Thermal comfort, rectal temperature, mean skin temperature, mean finger temperature (T(fing)), change in H(b) (DeltaH(b)), rate of body heat storage, Purdue pegboard test, finger tapping, handgrip, maximum voluntary contraction, and evoked twitch force of the first dorsal interosseus muscle were recorded. Results demonstrated that, unlike in HT and PHT, thermal comfort, rectal temperature, mean skin temperature, twitch force, maximum voluntary contraction, and finger tapping declined significantly in Con. In contrast, T(fing) and Purdue pegboard test remained constant only in HT. Generalized estimating equations demonstrated that DeltaH(b) and T(fing) were associated over time with hand function, whereas no significant association was detected for rate of body heat storage. It is concluded that increasing H(b) not only throughout but also before a coldEx is effective in maintaining hand function. In addition, we found that the best indicator of hand function is DeltaH(b) followed by T(fing).

Effect of Cold Conditions on Manual Performance while Wearing Petroleum Industry Protective Clothing

“…A study by Flouris et al 9) supports the findings of Brajkovic et al 7,8) , and further showed that not only maintaining H b during work but pre-heating before cold exposure is effective in maintaining hand function. Flouris et al 9) also showed that ∆H b was the best indicator of hand function followed by T fi .…”

“…Flouris et al 9) also showed that ∆H b was the best indicator of hand function followed by T fi . These findings demonstrate that decrements in manual performance are not due to reduced skin temperature alone, but are rather a result of changes in several variables.…”

“…These parameters have been T ha and T fi , body heat content (H b ) and changes in body heat content (∆H b ) [7][8][9][10] . Gaydos and Dusek 10) looked at the effect of local versus total body cooling and concluded that T fi seemed to be the primary determinant of impaired manual performance.…”

“…Previous studies on the effect of cold exposure on manual performance have focused on military clothing [7][8][9]11) and nuclear, biological and chemical (NBC) protective clothing 12) . Hence, we do not know whether the clothing used by petroleum workers provides sufficient protection against cold.…”

The Determination of Changes in Body Heat Content during Exercise Using Calorimetry and Thermometry

“…The thermometry approach is also limited to steady-state body temperatures both at rest and during exercise. Despite this, some authors (Flouris et al, 2006) have attempted to estimate DT ළ b and therefore DH b using the minute-by-minute integration of changes in "core" and "shell" temperature with fixed core-to-shell ratios. Since during exercise of varying intensity and/or lasting less than ϳ50 min, and during transient environmental conditions, body temperatures are nonsteady state; therefore the coefficients representing the "core" and "shell" will change considerably during this period (Gagge and Gonzales, 1996;Livingstone, 1967).…”