ABSTRACT: BACKGROUND: Meditation trainings are helpful for keeping physical and mental health. Regulating the heartbeat rhythm via autonomic nerve system may be the possible factor. The investigation of the relationship between training and heartbeat rhythm will deepen our understanding on the regulation rules of cardiovascular system and healthy training.OBJECTIVE: To investigate the regulation of heartbeat rhythm during meditation training from the aspect of complexity.METHODS: The heart rate variability series were obtained from meditation training database of PhysioNet. Permutation entropy was applied to analyze the data before and during Chi and yoga training. The effects of these two training methods on the complexity of heartbeat rhythm were investigated.RESULTS AND CONCLUSION: The permutation entropy of heart rate variability series during training was significantly smaller than that before meditation training; it indicated that both Chi and yoga training can reduce the complexity of heartbeat rhythm. Previous study on healthy young, healthy elderly and congestion heart failure subjects by permutation entropy showed that aging and disease could increase the value of permutation entropy. Thus, the regulation of the heartbeat rhythm via autonomic nerve system could be an important reason.Shen ZW, Shen YH, Bian CH, Ma QL. Effect of meditation training on heart rate variability based on permutation entropy.Zhongguo Zuzhi Gongcheng Yanjiu. 2012;16(44): 8256-8260.(Figure is included in full-text article.)