Effects of exercises on cardiac and gastric parasympathetic nerve activities in young adults

Thirteen young male subjects first lied in the supine position on bed with eyes opened for 10 min, followed by 10 min exercise of a cycle ergometer with a load randomly chosen among three different ones inducible heart rates as high as 15, 30, or 60% of the predicted maximal heart rate, and again took a supine position as during the first rest for 40 min. ECG and EGG were measured by using bio-amplifiers during all the experimental period, AD converted at the rate of 1kHz and stored into PC. RR-intervals obtained from ECG were Fourier transformed by every 64, serially from the top to the end of the file with doubling about its 50%. Cardiac sympathetic (CS) as well as parasympathetic nerve activities (CPS) were assumed from the power in high-frequency band (HF), and the relative magnitude of the power in low-frequency band (LF) to HF, respectively. EGG re-sampled by 10 Hz from the row EGG datum was Fourier transformed by every 512, serially from the top to the end, with doubling about its 50%. The power summed in the range between 2.4 and 3.6 cpm was assumed to be gastric parasympathetic nerve activities (GPS). CPS tended to increase only during 10-20 min district after 30% exercise (ex30). GPS was significantly increased during 10-15 min district (p<0.05) in the post-ex30 period. Either CPS or GPS after 60% exercise was significantly depressed. These results suggested that moderate exercise could augment parasympathetic nerve activities, particularly in the gastric region. [J Physiol Sci. 2006;56 Suppl:S143]