Influence of exercise, day-night rhythm, and respiration on heart rate variability

doi:10.3321/j.issn:1673-8225.2003.12.005

Abstract：Aim To explore the influence of exercise , day-night rhythm, and respiration on heart rate variability (HRV).Methods Thirty four voluntary subjects from a community in Chongqing City in 2000, were included in this self-controlled study. HRV signals at 5 am and 5 pm, at rest and after exercise , were recorded, measured, and analyzed , respectively. The standard deviation of consecutive cardiac cycles( SDNN) was used as an indicator of HRV. Results The 10 subjects' mean SDNNs at 5 am and 5 pm were 30 ms and 29 ms, respectively, whereas when the two sets of cardiac cycle data at 5 am and 5 pm were merged as one dataset, the SDNN increased to 262 ms; for 34 subjects, mean SDNN before exercise was 18 ms, and mean SDNN after exercise was 10 ms, in comparison of SDNN before exercise with that after exercise, the difference was significant (t=6.049, P< 0.01); the difference between the mean value of the maximal cardiac cycle difference in respiratory cycle I and that in cycle J was not significant (t=0.024, P >0.05). Conclusion One of the bases of the normal value ( 141± 39)ms of SDNN from 24 hours HRV recording is day-night variations of cardiac cycle; SDNN after exercise is decreased, exercise is an important factor influencing HRV; respiration has a certain influence on HRV but this influence is less than that of day-night variations of cardiac cycle. The method used in this study can simultaneously collect and record cardiac contractility and cardiac cycle signals, which might be a tool for analyzing HRV.