Skip to main content

Currently Skimming:

9 Influence of Cold Stress on Human Fluid Balance
Pages 161-180

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 161...
... . During physical work, mental stress, and/or exposure to climatic extremes, marked disruptions of body fluid balance can occur.
From page 162...
... Military Situation Regarding Fluid Balance in the Cold Sixty percent of the earth's land mass has January temperature lows below 32°F (0°C) , and over 25 percent of the earth's land mass experiences January temperature lows below 0°F (-18°C)
From page 163...
... The most significant factors are coldinduced diuresis, respiratory water losses, cold-weather clothing, metabolic cost of movement, and reduced fluid intake. Cold-Induced Diuresis Cold-induced diuresis (CID)
From page 164...
... 164 Cal ._ V]
From page 165...
... demonstrated an increase in urine flow to be the direct result of cold exposure. In 1940 Bazett and associates published a field study that confirmed that an increase in urine flow occurred with cold exposure, but also demonstrated commensurate reductions in plasma and blood volume.
From page 166...
... However, respiratory water losses do contribute to dehydration in the cold. As shown in Table 9-2, metabolic rate has a far greater impact than ambient temperature on respiratory fluid losses and, hence, on fluid requirements.
From page 167...
... 100 ~ 905 ml/24 h (-20) 100 ~ 1,020 ml/24 h NOTE: Effect of cold air itself could account for increased respiratory water losses as great as 340 ml/24 h, i.e., 50 percent increase.
From page 168...
... of clothing plus air necessary for comfort at various metabolic rates. (l Clo unit is equivalent to the insulation of a business suit, and 1 MET equals 100 watts.)
From page 169...
... Clothing cart be added when work rates decrease or removed when work rates and metabolic heat production increase. Metabolic Cost of Movement in Cold Terrain Figure 9-3 illustrates the effects of terrain associated with cold climates (e.g., snow)
From page 170...
... FREUND AND MICHAEL N SAWKA Reduced Fluid Intake The most important factor regarding fluid intake in the cold is the logistical constraint of fluid delivery.
From page 171...
... MILITARY IMPACT AND SIGNIFICANCE OF DEHYDRATION IN THE COLD It is clear that military operations conducted in cold climates can have a significant effect on body fluid balance. The impact of this dehydration and/or the direct effects that cold exposure can have on physical and cognitive performance, thermoregulation, and the susceptibility to cold injury are discussed below.
From page 172...
... In one group, euhydration was maintained while the second group was dehydrated by 2.5 percent body weight (prior fluid restriction and
From page 173...
... From their summary tables, it appears that dehydration representing as little as 2 percent loss of body weight can result in significant reductions in muscular strength, muscular endurance, and anaerobic work capacity, although some studies report no significant changes in the above parameters. Likewise, dehydration seems to cause a significant reduction in maximal aerobic power and maximal work capacity with decrements following a body weight loss of as little as 2 percent.
From page 174...
... For example, in moderately cold climates when individuals are wearing heavy clothing and are performing heavy work or exercise, it is conceivable that dehydration will exacerbate the core temperature rise and increase heat strain. In contrast, in severe cold or when work rates are low and body heat losses exceed heat production, dehydration probably has little effect on core temperature but may accentuate peripheral cooling (see below)
From page 175...
... Although further study is required, these studies provide evidence that differences in antidiuretic hormone response may be the mechanism responsible for improved fluid retention with glycerol. Alternatively, glycerol may directly affect the kidney's concentration gradients and hence water reabsorption.
From page 176...
... AUTHORS' CONCLUSIONS AND RECOMMENDATIONS In cold climates body fluid losses can be similar to those in hot environments and can result from sweating and increased respiratory water losses as well as cold-induced diuresis. Fluid intake in cold environments can also be reduced as a result of logistical constraints in fluid delivery, problems with the freezing of water, reduced thirst sensation, and voluntary fluid restriction.
From page 177...
... Gray 1986 Effects of hypohydration or cold exposure and restricted fluid intake upon cognitive performance. Technical Note T15-86.
From page 178...
... Granberg, and B Wedin 1974 Fluid balance and physical work capacity in humans exposed to cold.
From page 179...
... Issekutz, Jr. 1962 Effects of dietary protein on physical work capacity during severe cold stress.


This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More information on Chapter Skim is available.