Hydration during exercise in warm, humid conditions: effect of a caffeinated sports drink.

Caffeine is regarded as a diuretic despite evidence that hydration is not impaired with habitual ingestion. The purpose of this study was to determine whether a caffeinated sports drink impairs fluid delivery and hydration during exercise in warm, humid conditions (28.5 degrees C, 60% relative humidity). Sixteen cyclists completed 3 trials: placebo (P), carbohydrate-electrolyte (CE), [...]

Black tea–helpful or harmful? A review of the evidence.

OBJECTIVE: To consider whether consumption of black tea has a positive or negative impact on health. DESIGN: Databases were searched for relevant epidemiological and clinical studies published between 1990 and 2004. RESULTS: Clear evidence was found for coronary heart disease (CHD), where an intake of > or = 3 cups per day related to risk [...]

The effect of drinking tea at high altitude on hydration status and mood.

The effect of drinking tea on hydration status and mood was studied in nine male and four female members of expeditions based at Mt. Everest base camp at an altitude of 5,345 m. Whilst exposed to altitude-cold diuresis, participants were subjected to a crossover experimental design comprising two 24-h dietary interventions. In the "tea" condition, [...]

Caffeine vs caffeine-free sports drinks: effects on urine production at rest and during prolonged exercise

We compared the effects of caffeinated vs non-caffeinated carbohydrate electrolyte (CE) drinks on urine volume (UV), free water clearance (CH2O), fractional excretion of water (FEH2O), and osmolar excretion during 4 h of rest or 1 h rest followed by 3 h of cycling at 60% VO2max in six subjects. We also tested maximal performance at [...]