AbstractIn this study, the possible effects of exercise on hormonal secretions in some sport branches were investigated on the basis of urinary cyclic nucleotide (cAMP and cGMP) excretion, since it was thought that the total, ultimate effects of secreted hormones, under the effect of exercise stress, may be estimated by means of the changes in the second messenger, cAMP, and cGMP, concentrations in urine. A total of 60 subjects from different sport branches were included in the study, and pre- and post-training urinary cyclic nucleotide levels of them were determined by EIA method. The differences in cAMP and cGMP between pre-training and post-training periods were statistically significant (p < 0.05 for both), with the post-training levels being higher. The increased post-training cyclic nucleotide concentrations in urine showed that a complex hormonal response occurs as a result of both metabolic state and the exercise stress in sporters. It was concluded that the complicated hormonal status of the spor...