| Summary: | 碩士 === 輔仁大學 === 體育學系碩士班 === 93 === Although water does not contribute to the nutrient value for human body, it is still essential to life. Without water, death occurs within days. Water serves as the body’s transport and reactive medium, and it has tremendous heat-stabilizing qualities. From 40 to 60% of an individual’s body weight is water, and it constitutes 65 to 75% of the weight of muscle. Due to the important functions of the water, human body needs to remain the water relatively stable over time. Therefore, the water intake became an important issue to researchers. Chen (2004) conducted a study with two different temperatures of water intake, respectively, 4°C and 37°C in order to see if different temperature of water intake would affect automatic nervous system. His results showed there was no significantly difference to the automatic nervous system by drinking different temperature of water. Chen suspected the non-difference might be due to the training effect performed pre to the test, therefore, affected his study. In Chen’s study, he used the analysis of heart rate variability (HRV) to see the change of the excitation from the automatic nervous system in his young subjects. This technique is a non-offensive, simple, quantitative and easy to differentiate the excitation of sympathetic nervous system and parasympathetic nervous system, and was used by many researchers.
Therefore, the purpose of this study was to use the same technique of the analysis of heart rate variability Chen used:
1.To clarify if exercise pre to the measurement of heat rate variability would affect the excitation both in sympathetic nervous system and parasympathetic nervous system.
2.To investigate the effects of water temperatures (4°C and 37°C) to the resting heart rate variability.
Thirty healthy young athletes aged 16.53±0.68 were recruited in this study. ECG signals were recorded in supine position for 10 minutes before, and 20 minutes after 500 c.c. of water intake, and a total 30 minutes of ECG signal was collected. Two trails were performed for each subject by drinking two different temperatures of water, respectively, 4°C and 37°C at different day. All data was calculated for the time domain variability indices (mean, standard deviation and coefficient of variation of R-R interval) and frequency domain variables (total power spectrum, high frequency and low frequency, etc.). Comparisons between groups were then made by paired t tests.
The means of the R-R interval were significantly increased after drinking two different temperatures of water, especially for the drinking water at the temperature of 4°C. Although there was not significantly different in frequency domain after water intake, however, the data showed a trend of increasing values both in the high frequency and low frequency for 4°C of water, and in the high frequency for 37°C of water during the 20 minutes of resting period after water intake. This data showed a similar result as the study was done by Chen; therefore, it may suggest that the training effect performed pre to the measurement of heart rate variability may have no effect to the values of those variables in both time domain and frequency domain.
Key words: Hear rate variability, Autonomic nervous system, Water intake, Time domain, Frequency domain.
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