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 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 C water until esophageal temperature (Tes) reached 36.5 degreesC, 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.kg(-1).degreesC(-1) vs YNG = 3.56 +/- 1.53 W.kg(-1)degreesC(-1)). No significant differences (P > .05) were found for mean skin temperature (Tsk; OLD = 23.8 +/- 0.31degreesC vs YNG = 24.2degreesC +/- 0.19degreesC), HP (P > .05; OLD = 3.10 +/- 0.38 W.kg(-1) vs YNG = 2.50 +/- 0.22 W.kg(-1)), or Tes (OLD = 36.61degreesC +/- 0.11degreesC vs YNG = 36.74degreesC +/- 0.06degreesC). Conclusions.-Therefore, these data demonstrate that when faced with a cold challenge, there is a similar response in (3, HP, Tes, and Tsk between OLD and YNG individuals.