| Summary: | 碩士 === 輔仁大學 === 體育學系碩士班 === 94 === Abstract
We studied the heart rate variability (HRV) at cycling exercise in 16 high school elite basketball players and 15 age matched controls. A conventional lead II electrocardiogram was recorded for 10 minutes at baseline condition. Then these subjects had a cycling ergometers exercise and electrocardiogram at 160 watts for 10 minutes. After exercise, these subjects take a rest at sitting position and have the third session of electrocardiogram recording. The R-R interval was then calculated from the recorded electrocardiogram after R wave identification. The last stationary 512 RR intervals in each session were then used for HRV analysis. Time domain measures including mean of R-R intervals (RRI), standard deviation of R-R intervals (SD), Coefficient of variation (CV), the percent of R-R intervals differing > 50 ms from the preceding R-R (PNN50%) and standard deviation of the root mean square of the RRI (RMSSD) were calculated by statistics and the frequency domain measures including total power (TP), high frequency power (HFP), low frequency power (LFP), very low- frequency power (VLF), normalized high frequency power (nHFP), normalized low frequency power, (nLFP), and low-to-high frequency power ratio (LFP/HFP) were calculated by Fast Fourier transformation. A signed rank test was used to compare the HRV measures between elite and control groups. A repeated measures analysis of variance on rank was used to compare the HRV measures before, during and after exercise in both groups.
We found that all HRV measures did not differ significantly between elite and control groups at baseline condition. The elite group had higher mean RRI, HFP, LFP, nHFP and nLFP during exercise; and higher mean RRI, SD, CV, RMSSD, PNN50%, TP, HFP, LFP, VLFP, nHFP and LFP/HFP after exercise than those of the controls. All HRV measures except LFP/HFP decreased dramatically during exercise and then increased after exercise in both groups. The comparison between baseline and after exercise of the most HRV measures was not significantly in the elite group; whereas the comparison between during exercise and after exercise of the most HRV measures significantly in the control group. The elite group had a much lessened decrease in HRV at the same cycling load during exercise and had a more rapid recovery to baseline condition after exercise then those of the control group.
These results implied that the autonomic nervous control might not be different between elite and control group in the resting condition. The lessened decrease and rapid recovery in the HRV in response to the fixed load of exercise in the elite group implied that the elite group had a more efficient regulatory function in the modulation of the autonomic nervous system and HRV.
Key word: elite basketball players, high school students, heart rate variability, electrocardiogram, RR intervals, autonomic nervous activity.
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