1.衛生署桃園醫院內科, 桃園, 台灣＝Department of Medicine, Tao-Yuan General Hospital, Tao-Yuan, Taiwan; 2.台北榮總教學研究部, 台北, 台灣=Department of Medical Research and Education, Taipei Veterans General
數息是藉呼吸的操控練習來達到禪悅的境界. 在佛教經典中有許多關於數息及靜坐方法的記載. 目前各種靜坐方法中最廣為研究的是[超覺靜坐] ，它已被證實可造成許多良性的生理變化，並能降低老化，癌症，與其他疾病的罹病率與死亡率，然而針對佛教數息法所做的研究卻很少. 本研究嘗試以[心率變異度分析法] ，來評估靜坐調息對自律神經活性的效應. 受測者共有十二名年輕健康成年人，其中九名是男性，三名是女性. 他們先接受為期一個月的調息訓練，每天在相同時段練習三十分鐘，其方法是採取一個舒適的坐姿，閉上雙眼，集中注意力觀察每個呼氣與吸氣的動作，並摒除任何會分心的意念. 受測者在三種情況下接受測試，即仰臥休息，端坐休息及靜坐調息，其次序是由抽籤決定. 在進入各種不同狀態五分鐘後，利用心電圖監視器紀錄心電圖訊號約十分鐘，然後量測心電圖相鄰RR波間的間期，再進一步做頻譜分析. 我們以高頻功率比(高頻功率/總功率) 作為副交感神經活性的指標，低頻功率比(低頻功率/高頻功率)做為交感—副交感神經活性平衡的指標. 結果十二名志願者中，有十一名成功地完成測試，並列入分析. 這些受測者的高頻比率比在靜坐調息時最高，端坐休息時最低，仰臥休息時居間; 且靜坐調息與端坐休息或仰臥休息間的差異均有統計上的意義. 低頻功率比與高頻功率比率呈現相反的變化趨勢. 靜坐調息時的高頻功率顯著高於端坐休息時，高頻主峰頻率也顯著低於端坐休息時; 而總功率與低頻功率在這三種狀態間均無顯著差異—這些結果顯示在靜坐調息時的副交感神經活性比端坐休息及仰臥休息都來得高. 由臥姿轉為坐姿時，由於重力的影響，交感神經活化及副交感神經活性受限制的現象可以因靜坐調息而引發比仰臥休息還要高的副交感神經活性，因此靜坐調息應可作為一種生理性的副交感神經活性提昇法，從而在老化的預防與疾病的治療上扮演一個重要的角色. 至於靜坐調息時高頻功率比的上升機轉，應與呼吸頻率的下降有關，因高頻主峰頻率與高頻功率比有顯著的負相關. [數息法] 是佛教眾多修行法中，相當完備且內容浩瀚的一種方法. 本研究中的受測者採用簡單的方法，在經過短短一個月的練習後，即可以使靜坐調息時的副交感神經活化，且其活化程度甚至比仰臥休息時還明顯. 因經由這些簡單的練習，即可達到如此顯著的效應，所以我們相信進一步的練習可能會有更大的生理或超越心理的作用，這有待進一步研究的闡明. Breach-counting during meditation is a kind of respiration manipulation in order to achieve a status of tranquility and harmony. It has frequently been reported in the Buddhistical literature as an effective way of practice during meditation. Transcendental meditation was the most extensively studied among many methods of meditation. Transcendental meditation has been demonstrated to have beneficial effect on many physiological systems and can be used to decrease the process of aging，morbidity and mortality of cancer and other diseases. Although there were many comments on breath-counting in Buddhism，little studies on breath-counting meditation has been done in a scientific way. We tried to study the effect of breath-counting meditation on the autonomic nervous modulation by using heart arte variability analysis. Twelve young healthy subjects, nine male and three female，were recruited in this study. The study subjects had practiced breath-counting mediation for thirty minutes every day for one month before testing. During the breath-counting meditation，the subject sat quietly in a comfortable position，closed his or her eyes, and focused his or her attention on his or her own breathing. Each time the subject breathed in the air he or she counted it once in the mind until the tenth breath was reached. The subject then repeated the breath-counting from one to ten again and again. If the subject missed the number carelessly，he or she should start breath-counting from 'one' again. During the breath-counting meditation，the electrocardiogram of the subject was recorded randomly in three conditions, i.e.，supine rest，sitting rest and sitting meditation with breath-counting. The RR intervals in the electrocardiogram were measured afterwards to obtain the heart rate variability indices by using power spectral analysis. The normalized high-frequency power was used as the index of vagal modulation，the normalized low-frequency power as the index of sympathetic ond vagal modulation，and the low-/high-frequency power ratio as the index of sympatho-vagal balance. We found that eleven subjects successfully completed the testing and were included in the final analysis. The normalized high-frequency power was the highest in sitting meditation with breath-counting，followed by supine rest and sitting rest in decreasing order. The normalized low-frequency power and the low-/high-frequency power ratio had reversed trend as that of normalized high-frequency power among three conditions. There were no significant differences in the total power and low-frequency power among three conditions. When the posture was changed from supine to sitting，gravitational stress should activate the sympathetic nervous modulation and suppress the vagal modulation. The vagal suppressing effect was reversed when the subject practiced breath-counting meditation in sitting position. Sitting meditation with breath-counting might thus be used as a physiological vagal enhancer
