METABOLIC AND EXERCISE ENDURANCE EFFECTS OF COFFEE AND CAFFEINE INGESTION

Caffeine (Caf) ingestion increases plasma epinephrine (Epi) and exerci se endurance; these results are frequently transferred to coffee (Cof) consumption. We examined the impact of ingestion of the same dose of Caf in Cof or in water. Nine healthy, fit, young adults performed live trials after ingesting (double blind) either a capsule (Caf or placeb o) with water or Cof (decaffeinated Cof, decaffeinated with Caf added, or regular Cof). In all three Oaf trials, the Caf dose was 4.45 mg/kg body wt and the volume of liquid was 7.15 ml/kg. After 1 h of rest, t he subject ran at 85% of maximal O-2 consumption until voluntary exhau stion (similar to 32 min in the placebo and decaffeinated Cof tests). In the three Caf trials, the plasma Caf and paraxanthine concentration s were very similar. After Ih of rest, the plasma Epi was increased (P < 0.05) by Caf ingestion, but the increase was greater (P < 0.05) wit h Oaf capsules than with Cof. During the exercise there were no differ ences in Epi among the three Caf trials, and the Epi values were all g reater (P < 0.05) than in the other tests. Endurance was only increase d (P ( 0.05) in the Oaf capsule trial; there were no differences among the other four tests. One cannot extrapolate the effects of Oaf to Co f; there must be a component(s) of Cof that moderates the actions of C af.