The effect of capsaicin on the thermal and metabolic responses of men exposed to 38 degrees C for 120 minutes.
OBJECTIVE
To determine the thermoregulatory response of humans to heat following an ingestion of capsaicin.


METHODS
The thermoregulatory responses of 7 men (aged 22-28 years) to a 2-hour exposure to 38 degrees C (50% relative humidity) were compared following ingestion of either placebo or capsaicin. The capsaicin dose (2 mg x kg(-1)) was ingested 1 hour prior to the heat exposure, and all subjects were encouraged to overhydrate for 48 hours prior to each trial. Core temperature, mean skin temperature, cardiac output, and oxygen consumption were measured every 30 minutes. In addition, the changes (pre-exposure vs postexposure) in body mass and plasma volume were calculated.


RESULTS
As expected, core temperature, cardiac output, and oxygen consumption all increased significantly (P < .05) with exposure time. There were also significant decreases over time in body mass and plasma volume. These aforementioned changes, however, were not significantly different (P > .05) between the placebo and capsaicin trials, except for mean skin temperature. The treatment effect for mean skin temperature was significant (P = .013), with the capsaicin response (34.7 degrees C) registering lower than the placebo measurement (35.1 degrees C).


CONCLUSIONS
It appears that humans respond differently than animals to capsaicin ingestion. For humans, ingesting a 2-mg x kg(-1) dose of capsaicin 1 hour prior to heat exposure does not alter a person's ability to thermoregulate in the heat.
Nelson
A G
AG
Department of Kinesiology, Louisiana State University, Baton Rouge 70803, USA.
Glickman-Weiss
E
E
Day
R
R
D000328:Adult; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects*; D002211:Capsaicin / Q000494:pharmacology*; D005334:Fever / Q000378:metabolism*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D012016:Reference Values; D013997:Time Factors
D002211:Capsaicin