Urine melatonin and citrate excretion during the elite swimmers' training season.

The objectives of the study were to evaluate the influence of a whole training season on 6-sulfatoxymelatonin (αMT6s) and citrate excretion in 12 elite swimmers. Urine samples were obtained (before bedtime and after waking up) at the beginning of the season, basic training, macrocycle I, tapering and macrocycle II stages. For αMT6s, at basic training, mainly with aerobic training, the evening concentrations were significantly lower (P < 0.