This study was conducted to evaluate the influence of excessive sweating during long-distance running on the urinary concentration of caffeine after the intake of a large amount of caffeine. Nine endurance-trained athletes participated in a randomised cross-over study in which 450 mg caffeine were taken with and without exercise. Exercise consisted of running for 30 min on a treadmill at 75% of maximum heart rate, one hour after intake of caffeine. This endurance exercise caused a decrease in the urine flow as well as in the amount of caffeine excreted in urine. The combined effect of both these decreases is that the concentrations of caffeine detected in urine were similar with and without exercise. The maximum caffeine concentration detected in any urine sample was 11.9 micrograms/ml without exercise and 10.4 micrograms/ml with exercise. It can be concluded that excessive sweating during long-distance running did not enhance the urinary caffeine concentration.
The stability of some growth promoting agents in cattle urine, under various temperature storing conditions, was investigated. Bovine urine samples obtained from previous excretion studies which contained zeranol, nandrolone and trenbolone respectively, were stored frozen, at room temperature and in direct sunlight. On days 0, 2, 4, 7 and 10, zeranol and nandrolone were quantified by selective ion monitoring analysis on a gas chromatography-mass selective detector and trenbolone by using an enzyme linked immunosorbent assay. Zeranol and its metabolite taleranol are stable under all of these storage conditions. There is a remarkable decrease in the concentration of 17 alpha-19-nortestosterone, the main metabolite of nandrolone in cattle, when stored at room temperature and in direct sunlight. There is also a decrease in concentration of trenbolone when stored in direct sunlight. From the results it can be concluded that urine specimens obtained from cattle for residue analysis should be frozen as soon as possible after collection.
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