Impaired Metabolic And Tissue Insulation Responses To Cold In Aged Humans

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S213???S214
Author(s):  
David W. DeGroot ◽  
W. Larry Kenney
Keyword(s):  
Tissue Insulation

Metabolic and thermal responses of women during cooling in water

1974 ◽  
Vol 36 (5) ◽  
pp. 577-580 ◽  
Author(s):  
J. Kollias ◽  
L. Barlett ◽  
V. Bergsteinova ◽  
J. S. Skinner ◽  
E. R. Buskirk ◽  
...  
Keyword(s):  
Body Fat ◽  
Young Women ◽  
Heat Production ◽  
Cold Exposure ◽  
Korean Women ◽  
Mass Ratio ◽  
Body Fatness ◽  
Body Fat Content ◽  
Tissue Insulation ◽  
Skin Temperatures

The metabolic and thermal responses of 10 young women, 3 lean (21–24% fat) and 7 obese (29–41% fat), were measured during head-out immersion in a stirred water bath maintained at 20°C. Continuous measurements of heat production (M), rectal (Tre, esophageal (Tes), and skin temperatures were obtained. The rate and magnitude of the increase in M and decrease in core temperatures were significantly greater in the lean than the obese group. Tissue insulation values for lean women were similar to those reported for diving and nondiving Korean women in 30°C water. Lean women with 22% body fat have a larger SA/mass ratio than men of comparable body fat content and cool at a greater rate. It is concluded that SA/mass as well as body fatness and size must be considered in the overall metabolic and thermal responses to cold exposure.

scholarly journals EFFECTS OF COLD ENVIRONMENTS ON THE ENERGY EXCHANGES OF YOUNG BEEF CATTLE

1970 ◽  
Vol 50 (1) ◽  
pp. 89-100 ◽  
Author(s):  
A. J. F. WEBSTER ◽  
J. CHLUMECKY ◽  
B. A. YOUNG
Keyword(s):  
Body Weight ◽  
Critical Temperature ◽  
Beef Cattle ◽  
Environmental Control ◽  
Weather Conditions ◽  
Cold Climates ◽  
Cold Environments ◽  
External Insulation ◽  
Energy Exchanges ◽  
Tissue Insulation

Groups of four heifers were kept over winter at 20 C (controls) or outdoors with (sheltered) or without (exposed) shelter. Weather conditions were severe. Mean January temperature was −28 C. All animals received the same amount of grain. Calves in the control, sheltered and exposed groups ate on average 9.0, 11.3 and 10.9 g hay/kg body weight per day and gained, over winter, 156, 158 and 140 kg, respectively. Growth of new hair was similar in all groups. However, total hair cover in the cattle kept outside was, in February, twice that of the controls. This increase was attributed to reduced hair shedding. Tissue insulation increased throughout in all groups. External insulation was markedly reduced by exposure of the animals to wind. The influence of coat depth on external insulation was small. Still air critical temperature for the controls fell from 7 to −2 C during the experiment. The effect of acclimatization was to reduce critical temperature to −18 C in the sheltered group during February.The results are discussed with respect to the nature and extent of environmental control required for beef production in cold climates.

Impaired Metabolic And Tissue Insulation Responses To Cold In Aged Humans

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S213-S214
Author(s):  
David W. DeGroot ◽  
W. Larry Kenney
Keyword(s):  
Tissue Insulation

Effects of body mass and morphology on thermal responses in water

1986 ◽  
Vol 60 (2) ◽  
pp. 521-525 ◽  
Author(s):  
M. M. Toner ◽  
M. N. Sawka ◽  
M. E. Foley ◽  
K. B. Pandolf
Keyword(s):  
Metabolic Rate ◽  
Body Mass ◽  
Small Body ◽  
Large Body ◽  
Esophageal Temperature ◽  
Mass Ratio ◽  
Total Body Fat ◽  
Tissue Insulation ◽  
Total Body ◽  
Intensity Of Exercise

Ten male volunteers were divided into two groups based on body morphology and mass. The large-body mass (LM) group (n = 5) was 16.3 kg heavier and 0.22 cm2 X kg-1 X 10(-2) smaller in surface area-to-mass ratio (AD X wt-1) (P less than 0.05) than the small-body mass (SM) group (n = 5). Both groups were similar in total body fat and skinfold thicknesses (P greater than 0.05). All individuals were immersed for 1 h in stirred water at 26 degrees C during both rest and one intensity of exercise (metabolic rate approximately 550 W). During resting exposures metabolic rate (M) and rectal temperature (Tre) were not different (P greater than 0.05) between the LM and SM groups at min 60. Esophageal temperature (Tes) was higher (P less than 0.05) for the SM group at min 60, although the change in Tes during the 60 min between groups was similar (LM, -0.4 degrees C; SM, -0.2 degrees C). Tissue insulation (I) was lower (P less than 0.05) for SM (0.061 degrees C X m-2 X W-1) compared with the LM group (0.098 degrees C X m-2 X W-1). During exercise M, Tre, Tes, and I were not different (P greater than 0.05) between groups at min 60. These data illustrate that a greater body mass between individuals increases the overall tissue insulation during rest, most likely as a result of a greater volume of muscle tissue to provide insulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological adjustment to repeated wind exposure in sheep

1969 ◽  
Vol 11 (4) ◽  
pp. 493-498 ◽  
Author(s):  
J. G. Griffiths ◽  
J. M. Doney
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Air Flow ◽  
Progressive Increase ◽  
Gradual Decrease ◽  
Wind Exposure ◽  
Tissue Insulation

SUMMARYAn experiment was undertaken to examine the possibility that progressive adjustments in tissue insulation on the trunk might occur following repeated wind cooling. Two sheep were exposed at right angles to an air flow of 12 mph for 6 hr daily on each of 7 consecutive days.When first exposed to the wind the heat loss from the fleece-covered surfaces increased due to a reduction in insulation and apparently increased vaso-dilatation. After the first day there was a progressive increase in surface vaso-constriction before exposure and a gradual decrease in the extent of the vaso-dilatation during exposure. The results indicate the possibility of centrally-induced peripheral adjustments in blood flow occurring on the trunk of the sheep in response to repeated wind cooling.

Mechanisms of cold acclimatization in the cat

1963 ◽  
Vol 18 (4) ◽  
pp. 778-780 ◽  
Author(s):  
Thomas Adams
Keyword(s):  
Cold Exposure ◽  
Whole Body ◽  
Metabolic Rates ◽  
Body Temperatures ◽  
Peripheral Vascular ◽  
Air Exposure ◽  
Cold Acclimatization ◽  
Tissue Insulation ◽  
Body Heat ◽  
Internal Body

Thermoregulatory control in cats living at 25 C was compared to the regulation of body temperature in the same species after continuous whole-body cold exposure to an ambient temperature of 5 C for periods exceeding 2 months. Rectal and extremity temperatures and metabolic rates for the two groups were examined during acute (2-hr) air exposures to 23, 10, and 0 C. Cold acclimatizing mechanisms in the cat involve a redistribution of body heat at 23 C, obligating increased heat flux at the expense of elevated metabolism, an improved peripheral vascular defense (increase functional tissue insulation) during moderate cold exposure (10 C), and a greater ability to increase heat production accompanied by more labile peripheral vasomotion, during more severe cold air exposure (0 C). Although resting at 23 C, cold-acclimatized cats had lower rectal temperatures and were able to maintain higher internal body temperatures during both levels of cold stress compared to noncold-acclimatized animals. Submitted on November 1, 1962

Thermal insulation and shivering threshold in Greek sponge divers

1982 ◽  
Vol 52 (4) ◽  
pp. 845-850 ◽  
Author(s):  
A. Veicsteinas ◽  
D. W. Rennie
Keyword(s):  
Sharp Increase ◽  
Cold Water ◽  
Subcutaneous Fat ◽  
Long Time ◽  
Subcutaneous Fat Thickness ◽  
Fat Thickness ◽  
Tissue Insulation ◽  
Relationship Of ◽  
The Relationship ◽  
Average Skin

Sublingual temperature (Tor), average skin temperature (Tsk), and skin heat flow (Hsk) were determined in a field study for six Greek sponge divers and seven nondiving controls during head-out immersions at water temperature of 21 degrees C. Wetsuits kept Tsk at 22–28 degrees C for 1–3 h until Tor fell to 36.5–35.5 degrees C and violent shivering [metabolic rate (M) = 100–150 W . m-2] ended the test. At a steady Tsk, immediately before shivering, overall tissue insulation (It), calculated as (Tor--Tsk)/Hsk, was linearly related to mean subcutaneous fat thickness (MFT) in both groups without statistical difference between them. The onset of shivering, as detected by a sharp increase of M, occurred at the same Tor for a Tsk of about 26 degrees C, and the relationship of M vs. Tor (i.e., metabolic sensitivity) was the same for both groups. Contrary to other groups accustomed to diving in cold water, the use of a wetsuit for a long time has evidently prevented cold adaptation in these divers.

Method for measuring regional heat losses in man

1980 ◽  
Vol 49 (3) ◽  
pp. 533-535 ◽  
Author(s):  
A. R. Gin ◽  
M. G. Hayward ◽  
W. R. Keatinge
Keyword(s):  
Blood Flow ◽  
Heat Flow ◽  
Heat Loss ◽  
Local Heat ◽  
Heat Losses ◽  
Cutaneous Blood Flow ◽  
Rubber Sheet ◽  
Tissue Insulation ◽  
Flow Devices ◽  
Cutaneous Blood

Flexible heat flow devices were constructed from 0.4-mm-thick nylon-reinforced rubber sheet, with multiple copper-constantan thermocouples on each side to measure mean temperature difference across the sheet. A method of calibration is described that corrects for the alteration of local heat loss produced by the device itself. It was shown that such errors would otherwise be large when cutaneous blood flow was high, and tissue insulation low, even with devices as thin as these.

Effects of fitness, fatness, and age on men's responses to whole body cooling in air

1991 ◽  
Vol 71 (6) ◽  
pp. 2387-2393 ◽  
Author(s):  
G. M. Budd ◽  
J. R. Brotherhood ◽  
A. L. Hendrie ◽  
S. E. Jeffery
Keyword(s):  
Multiple Regression ◽  
Skinfold Thickness ◽  
Fat Free Mass ◽  
Whole Body ◽  
Skin Fold Thickness ◽  
Skin Fold ◽  
Vasoconstrictor Response ◽  
Tissue Insulation ◽  
Body Cooling ◽  
Whole Body Cooling

Simple and multiple regression analyses were used to assess the influence of 12 white men's fitness (aerobic capacity 44–58 ml O2.min-1.kg fat-free mass-1), fatness (mean skin-fold thickness 5–20 mm, body fat content 15–36%), and age (26–52 yr) on their thermal, metabolic, cardiovascular, and subjective responses to 2 h of whole body cooling, nude, in air at 10 degrees C. Fitter men had slower heart rates, and fatter men had higher blood pressures. Fitness had no effect (P greater than 0.39) on any measured response to cold. Fatness was associated (P less than 0.01) with reduced heat loss, heat production, and mean skin temperature; unchanged heat debt; and increased tissue insulation. Age had the opposite effects. When the confounding effects of fatness were held constant by multiple regression, older men responded to cold as though they were 1 mm of skinfold thickness leaner for each 3–4 yr of age. We conclude that aging, even between the relatively youthful ages of 26 and 52 yr, is accompanied by a progressive weakening of the vasoconstrictor response to cold.

DIRECT EFFECTS OF COLD WEATHER ON THE ENERGETIC EFFICIENCY OF BEEF PRODUCTION IN DIFFERENT REGIONS OF CANADA

1970 ◽  
Vol 50 (3) ◽  
pp. 563-573 ◽  
Author(s):  
A. J. F. WEBSTER
Keyword(s):  
Environmental Control ◽  
Task Force ◽  
Cold Weather ◽  
Energetic Efficiency ◽  
Regression Equations ◽  
Beef Production ◽  
Critical Temperatures ◽  
Feeder Cattle ◽  
Direct Measurements ◽  
Tissue Insulation

Direct measurements of the energy exchanges of cattle in cold and windy environments were used to derive partial regression equations predicting the effects of air temperature and body weight on tissue insulation, and wind speed and coat depth on external insulation. These measurements were combined with estimates of thermoneutral heat production to predict still air critical temperatures for feeder steers, pregnant cows and growing calves. These values ranged from −31 to −38, −11 to −23, and −16 to −21 C in the three groups, respectively. Meteorological records from different sites in Canada showed that cold has a negligible effect on the energetic efficiency of sheltered feeder cattle. The effects of cold on pregnant cows and growing calves are significant but not excessive. Examples are presented of the extent to which wind, sunshine and precipitation may influence critical temperature and the results are discussed in terms of regional disparities within Canada in the costs of keeping beef cattle, the economics of environmental control and the recommendations with respect to beef production of the Canadian Federal Task Force on Agriculture.

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