freakin me out -
The effect of caffeine administration on thermoregulatory and myocardial function during endurance performance was studied.
A caffeine solution (250 ml; 5 mg caffeine/kg body weight) ingested 1 hour prior to 2 hours of running by 5 subjects was shown to have no significant effect on sweat loss, water deficit, percentage change in plasma volume, final rectal temperature and serum electrolyte levels, as compared with a similar control group who were given a caffeine-free drink.
The rectal temperatures in both groups did, however, reach levels known to be associated with heatstroke despite a recommended regimen of fluid replacement. No pathological electrocardiographic changes occurred in either group.
It is therefore concluded that the use of caffeine for ergogenic purposes by young athletes is a relatively safe procedure.
rectal temperature ... ick.