The Effect of a Submaximal Swimming Program on Plasma ANP Concentration and its Relationships with Essential Hypertension in Middle-Age Males

The purpose of this study was to investigate the effect of a selected submaximal swimming training on BP and plasma [ANP] among middle age males with EH. In this research, 30 subjects aged 40-55 years with mild EH for at least 2 years, were selected. The subjects were randomly divided into EXP and CON groups. The CON group were asked to continue their normal life but were closely observed. The EXP group was guided to participate in training protocol for 28 sessions, 3 days a week. In each session subjects were asked to swim at 60-65% of Maximum pulse rate for 55 to 60 min. The Bruce treadmill test was conducted to determine the aerobic capacity of subjects. The Doppler M. Mode Echocardiography test showed that subjects had no problems to participate in training protocol. Pulse rate was used to control the training intensity. Sys and dia BP of each EXP subject was measured before and after training session and blood samples were taken at four stages, before training started, 30 min, 24 h and two weeks after last training session. [ANP] was also measured by RIA method. The t-test, (P<0.05), was used to test the hypotheses. The findings are as follows: In EXP group there was a significant difference between sys and dia BP before and after each session. There was also a significant difference between [ANP] in EXP group before training started, 30 min, 24 h and 2 weeks after the last training session. In addition, there was significant differences between sys and dia BP and [ANP] of EXP group before training started and 24 h after the last training session. The results revealed that following a submaximal swimming training protocol, the sys and dia BP would decrease to safe border which might be due to the increase of [ANP].