Abstract

Nitric oxide is a potent vasodilator, and endothelin-1 is a potent vasoconstrictor ‎peptide, which is produced by endothelial cells. The present study was conducted to ‎examine the effect of a 12-week regular aquatic exercise program on plasma levels of ‎nitric oxide, endothelin-1, and some platelet indices in healthy young men.‎ The subjects were 24 healthy young men, who were randomly assigned to two groups ‎of experimental (n=12) and control (n=12). Both groups were similar regarding their ‎age and body mass index. Practice protocol in the experimental group included a 12-‎week swimming program (three sessions a week) with an intensity of 55-75% of the ‎maximum heart rate. Participants in the control group did not take part in any regular ‎physical activity program during the study. Blood samples were taken 48 hours after ‎the initiation of the practice protocol for measuring levels of nitric oxide, endothelin-1, ‎and some platelet indices. Independent and dependent t-tests were run to compare the ‎means of the examined parameters (α=0.05).‎ The results indicated that, in the experimental group, the level of nitric oxide increased ‎‎(p=0.003); but, the level of endothelin-1 (p=0.029), platelet count (p=0.004), mean ‎platelet volume (MPV) (p=0.29) and platelet count percentage (p=0.001) significantly ‎decreased. Between-group comparison showed that changes in the level of nitric oxide ‎‎(p=0.035) and platelet count percentage (p=0.003) were significant, while those of ‎platelet count (p=0.066) and MPV (p=0.62) were not significant statistically. ‎

Based on the results of this study, aquatic aerobic exercise can reduce the risk of ‎hypertension in healthy young men by increasing the level of nitric oxide and ‎decreasing the level of endothelin-1‎‎‎‎‎‎‎‎‎‎.