In a study analyzing the
effect of caffeine on sport -
specific endurance performances, researchers found that
caffeine increased race times by an average
of 3 % which is equivalent to 2 minutes an hour.
One measured fluid, electrolyte, and renal indices
of hydration over eleven days
of caffeine consumption in human subjects, finding that doses
of up to 6 mg
caffeine per kilogram
of body weight had no
effect on body mass, urine osmolality (urine concentration), urine
specific gravity (concentration
of excreted materials in urine), urine color, urine volume, sodium excretion, potassium secretion, creatinine content, blood urea nitrogen (forms when protein breaks down), and serum levels
of sodium and potassium.