Thermal, cardiovascular & thermogenic responses to mild cold exposure in chronically energy deficient human subjects.

Thirteen young, male adults were investigated for thermal, cardiovascular and metabolic responses to truncal cooling for 40 min. The subjects were divided into two groups [well nourished controls (WN) and chronically energy deficient (CED)] on the basis of anthropometry and socio-economic status. The CED group had significantly greater reductions in peripheral forearm blood flow and surface finger tip temperatures on exposure to cold when compared to the well nourished controls. The CED group also showed a significant rise in oxygen consumption (3.4%), while no thermogenic response was observed in the WN controls. There was no fall in deep body temperature in either group. The study suggests that chronically energy deficient subjects thermoregulate appropriately on exposure to mild cold. The deficiency in insulative body fat is made up for by evoking greater peripheral vasoconstrictor responses as well as thermogenic mechanisms. The study suggests that on exposure to cold, thermoregulation takes precedence over energy conservation in chronically energy deficient subjects.

Superficial thermal gradients during mild body cooling and its relationship to forearm blood flow.

Forearm and fingertip temperature gradients were related to simultaneously measured forearm blood flow in eleven adult subjects at rest and during a mild cold stimulus. The change in temperature gradients were converted into a percentage change of the potential capacity for heat exchange and this was found to correlate well (r = 0.73: P < 0.001) with the absolute reduction in forearm blood flow.