1、1The theory and practice of heart rate variability in training applicationAbstract. The heart rate is an important physiological indicator， and some of the physiological and pathological changes in the human body can be understood through changes in heart rate. Changes of heart rate exercise load ca
2、n reflect the changes in the regulation of the nervous system of the heart and the physical condition of the subjects. In the past， people used to think that the heart rate of healthy person is regular， and is in line with the steady-state principle. People gradually take seriously in view of the he
3、art rate variability analysis， as well as indicators and related diseases. This paper mainly explains the theory and practice of heart rate variability in training application. Key words： heart rate variability； training application； nervous system 1.Overview of heart rate variability 1.1 Noninvasiv
4、e diagnostic methods for heart rate variability Analysis of heart rate variability （HRV） is a noninvasive 2diagnostic method for the evaluation of the autonomic nervous function， and it has an independent predicting value to sudden cardiac death. Heart rate variability has drawn increasing attention
5、， and connects the absence of heart rate variability with the occurrence of a variety of heart disease （including heart failure， myocardial infarction， cardiac sudden death， aging， autonomic nervous system dysfunction， etc.）. The traditional research methods of heart rate variability embody time dom
6、ain and frequency domain. Time domain methods calculate the average and standard deviation of the heart rate. It is simpler， but with low sensitivity， poor specificity， and cannot fully display the dynamic process of the HRV signal. Currently the more commonly used method is the use of power spectra
7、l analysis of the change in the HRV signal. Numerous studies show that the power spectrum can reflect the activity of the sympathetic， parasympathetic modulation of heart rate， but this modulation process is non-linear， and most of the biomedical signal nonlinear spectral analysis is basically the l
8、inear analysis， so this method may make some useful information not to be sufficiently extracted. Therefore， the application of nonlinear dynamics analysis of biomedical signals is winning more and more attention. 31.2 HRV analysis is the indicator for quantitative detection of autonomic function As
9、 the indicators for quantitative detection of autonomic function， HRV analysis has been recognized as an independent factor for the prediction of sudden cardiac death. The current time domain and frequency domain analysis methods can not reveal all the HRV connotations， in strict accordance with the
10、 sensitivity， specificity statistics by the large number of clinical studies， the positive predictive value of sudden death is still less than 30%. The indicators of the physiological significance which we are using currently are relatively consistent with the understanding： the time domain indicato
11、rs reflect changes in vague nerve， the HF of frequency domain reflect flexibility of vague nerve， LF mainly reflects sympathetic activity， and LF / HF then reflect sympathetic the balance of fans walk nerve adjustment. The Games can decrease the excitability of the parasympathetic and enhance the sy
12、mpathetic activity， result in the imbalance of the autonomic nervous system in the adjustment of the heart， and information of these cardiovascular regulations can be learned from the analysis and extraction of HRV. 1.3 Relationships between heart rate variability and autonomic nervous tension 4Irre
13、gularities of heart rate changes of healthy person are mainly related with the interaction of the sympathetic and parasympathetic nervous system. If the autonomic nervous system regulation diminished or disappeared because of some reasons （such as disease or nerve blocker） ， it will cause some indic
14、ators to reduce even becomes zero. Therefore， many scholars detect HRV as important indicators of the evaluation of the autonomic nervous system tension， but we cannot simply believe that HRV decrease in any case means the decline of the autonomic nervous tension. When parasympathetic nervous tensio
15、n continues to increase and saturate sinus node stimulation， the HRV of high-frequency fluctuations will dampen instead， showing that although the high vague nerve tension has the opposite effect on the block of vague nerve on the heart rate， the impact on HRV is similar， both will cause HRV less. S
16、ome animal experiments also confirm that the two kinds of state regulating autonomic nerve stimulation and saturated autonomic nerve stimulation reaction are different. From all comprehensive study， HRV decrease reflects the decline in autonomic regulation dysfunction or sinus node， and the decline
17、in the latter case also appears when the autonomic nervous tension is too high. 51.4 Relaxation training can improve heart rate variability Studies have shown that relaxation training significantly improves the heart rate variability of subjects. on one hand， it can reduce sympathetic tone and the b
18、ody tension levels， enable the body vague nerve and sympathetic activity of practitioners remain at a good balanced state to against various stress； the result also shows that brain index increases in both values in the lower part， of which index minimum of two temporal are the most significant. Thi
19、s is consistent with the findings of the reports， after repeated relaxation training， subjects EEG synchronization trend becomes higher， and the degree of ordering of the whole brain is improved. Training improves mood， decreases subjective symptoms， and improves the quality of sleep. 1.5 Visceral a
20、ctivity and heart rate variability EEG， heart rate variability， and emotional status are closely related. They affect each other and promote each other to form a virtuous circle. Relaxation training improves brain function， and thus improves the mood of its practitioners， and through regulating the
21、autonomic nervous activity， it improves the activities of the internal organs， so that the brain， internal organs， activities， emotions， and body are 6in a harmonious state， and beneficial against stress to improve the physical and mental health. The harmonious state of relaxing into the static not
22、only affects the brain， the brain also affects the activity of the autonomic nervous system to improve the function of internal organs， directly and indirectly improve the emotional and mental activities of the human body， let the whole body in a special integration status， and the central nervous s
23、ystem， autonomic nervous system， the various offal system and mind in a good coordination of the state， then the entire human body tends to be orderly， synchronized， and in this state， the body can effectively combat stress reaction. 2.Exercise and heart rate variability 2.1 Exercise Stress Exercise
24、 is a kind of stress on the body of the original， the consumption of energy， triggering a series of changes in the tissues and organs to change the environment for the body. On one hand， it produces a good effect on the body， and therefore becomes one of the methods for the treatment of some chronic
25、 diseases； on the other hand， it can also cause damage to the body， for example， the excessive secretion of catecholamine caused by movement， results in a significant 7increase of a strong contraction of blood vessels， coronary spasm and myocardial oxygen consumption； causes hyper and thrombosis， my
26、ocardial cell membrane electrical instability， arrhythmia， and even cardiac arrest， sudden death. In order to ensure the efficiency of movement， it is necessary to develop a safe and effective exercise prescription. The prescription of exercise embodies exercise intensity and duration， exercise freq
27、uency， exercise type， exercise precautions. 2.2 Influence of exercise on heart rate variability Before the start of a large amount of exercise activities （e.g.， treadmill exercise） ， the cardiac autonomic nerve of healthy people transfers the resting sympatric neural mutual equilibrium to the sympat
28、hetic dominant movement direction. Different exercise amount causes different HRV changes. Nervous tension decline in the middle amount of movement， when the fans strike mainly by sympathetic dominant for the large amount of exercise， vague tone no longer continues to decline， vague nerve determines
29、 the value of HRV when lying， plasma catecholamine concentrations and LF / HF ratio is inversely proportional to the movement， it may make negative feedback effect on the presence of catecholamine sympathetic tone. 8Postural also have an impact on heart rate variability. It was found that the when r
30、ecumbent riding car， LF value is significantly lower than repose， while seat riding car， LF value has no significant difference with sit-bit. 2.3 HRV distinctions between regular exercise and irregular exercise When athletes are quiet， low cardiac will occur to them. The reason of low cardiac for at
31、hletes， especially endurance athletes after long training， in addition to the reason of the increase of cardiac， the increase of disposable cardiac nerve tension change is a very important reason. Under normal circumstances， the sympathetic and the fans nerves sinus node role is 25/50， but trough tr
32、aining， this proportional relationship can be changed to 15/45， In other words， the training can make sympathetic and vague tension declines， while the decline is more significant in sympathetic tone， so as to cause a decrease in heart rate. 3. Evaluation methods of heart rate variability 3.1 Nonlin
33、ear methods of HRV analysis The current nonlinear methods to the study of the HRV mainly include draw scatter plots and extract various nonlinear indicators such as complexity， approximate entropy. These 9indicators describe the complexity of the HRV signal from different angles， so as to reflect th
34、e nonlinear characteristics of the cardiovascular system. Described a chaotic degree of freedom of information as a fractal dimension， correlation dimension， is a method of measuring the strange attractor chaotic dynamics， and has been put into a lot of applications in HRV research. The study of dil
35、ated cardiac and find that HRV correlation dimension of this type of patient is significantly lower than healthy people； the study of heart rate of normal people and the elderly， and find that the normal correlation dimension is significantly higher than that for the elderly； the study of correlatio
36、n dimension of acute myocardial ischemia， and these studies show that the correlation dimension has a correlation with the functional status of the heart. Compared with static physiological signals， dynamic physiological stress signals contain more information， and may extract more effective feature
37、s to reflect the physiological system status. 3.2 Frequency domain analysis of heart rate variability Frequency domain analysis， namely the power spectrum analysis， provides the basic information of the distribution of energy with frequency change， the time domain signal 10spectrum estimation can be
38、 obtained only through appropriate mathematical operation. The Act further provides changes of a sympathetic and vague activity level and balance. 3.3 Classic spectral estimation method and the parameters of the model spectrum estimation method Classical spectrum estimation method and parameters of
39、the model spectrum estimation method both have their advantages and disadvantages. The main advantages of the classical spectrum estimation method are： 1） the use of a algorithm is simple （fast Fourier transform） ； 2） Operator fast. The main disadvantages are： the spectrum is not very smooth. The ma
40、in advantages of the parametric model spectrum estimation method are： 1） the spectral line is smooth， easy to identify； 2） high resolution. Its main drawback is： the complex modeling process， model order is not easy to determine， the requirements of the data are stationary series. Through efficiency
41、 spectrum evaluation， it is available to the signal high-frequency energy （HF） ， a number of indicators of the total energy of low-frequency energy （LF） ， extremely low frequency the energy （VLF） ， LF / HF and the segment energy peak. 3.4 Nonlinear Analysis of clinical evaluation The importance of the nonlinear dynamics theory to science
