The influence of age on thermosensitivity during cold water immersion.
OBJECTIVE
This investigation evaluated the influence of older age (OLD) vs younger age (YNG) on thermosensitivity and metabolic heat production (HP) during cold water immersion (20 degrees C) in 15 YNG (22.7 +/- 2.7 years) vs 7 OLD (41.7 +/- 2.7 years) individuals.


METHODS
After a 20-minute baseline (BASE) period, subjects were immersed in 20 degrees C water until esophageal temperature (Tes) reached 36.5 degrees C, or for a maximum preocclusion (pre-OCC) time of 40 minutes. Arm and thigh cuffs were then inflated to 180 and 220 mm Hg, respectively, for 10 minutes (termed "occlusion" [OCC]). After release of the inflated cuffs (postocclusion [post-OCC]), the slope (beta) of the relationship between the decrease in Tes and the increase in HP was used to quantify thermosensitivity.


RESULTS
Analysis of variance showed no significant difference in thermosensitivity between OLD and YNG (OLD = 2.25 +/- 1.72 W x kg(-1) x degrees C(-1) vs YNG = 3.56 +/- 1.53 W x kg(-1) x degrees C(-1)). No significant differences (P > .05) were found for mean skin temperature (Tsk; OLD = 23.8 degrees C +/- 0.31 degrees C vs YNG = 24.2 degrees C +/- 0.19 degrees C), HP (P > .05; OLD = 3.10 +/- 0.38 W x kg(-1) vs YNG = 2.50 +/- 0.22 W x kg(-1)), or Tes (OLD = 36.61 degrees C +/- 0.11 degrees C vs YNG = 36.74 degrees C +/- 0.06 degrees C).


CONCLUSIONS
Therefore, these data demonstrate that when faced with a cold challenge, there is a similar response in beta, HP, Tes, and Tsk between OLD and YNG individuals.
D000328:Adult; D000375:Aging; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D003080:Cold Temperature; D004947:Esophagus / Q000502:physiology; D006801:Humans; D007035:Hypothermia / Q000503:physiopathology*; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D022722:Thermogenesis / Q000502:physiology*