Impact of Health Qigong • Yi Jin Jing on Heart Rate Variability (HRV) of the Old and Middle-aged People

In the old and middle-aged crowds, with increasing age, the occurrence of cardiovascular disease or bearing of mental loads (such as remain in the prolonged state of high-load tension work environment and work pressure, etc.) would lead to the increase in sympathetic nerve activity and the decrease in vagus nerve and HRV[1]. Studies have shown that long-term participation in aerobic fitness exercise can enhance the tension of vagus nerve of the old and middle-aged people, the enhancement in tension of vagus nerve makes the threshold for the occurrence of ventricular fibrillation increased, thus playing a protective effect on the heart [2]. In order to observe the impact of Health Qigong • Yi Jin Jing on autonomic nervous system functions, our research group conducted HRV tests against experimental group and control group when the experiment has been carried out for 10 months.

8.2.1 Objects and methods

8.2.1.1 Objects
This study selected the elderly learners aged between 50 and 70 without history of systematic exercise or serious illness from University for the Aged of Jiangxi Province and Veteran Cadre Activity Center of Jiangxi Provincial Party Committee as the experimental objects. The t-test (t=0.67, P ＞ 0.05) was conducted against 64 female experimental objects that were selected from experimental group and control group including 37 from experimental group (aged 62.76±6.18) and 27 from control group (aged 63.74±5.15) and indicated that the two groups has no significant difference in ages.

8.2.1.2 Methods
The experimental group practiced Health Qigong • Yi Jin Jing for one hour every morning no less than five days a week and the exercise instructors were assigned to provide coaching and guidance for these objects. The exercise routines, practicing requirements, teaching guidance of Health Qigong • Yi Jin Jing are based on the official version released by GASC Health Qigong Administration Center [3]. The control group did not participate in Health Qigong exercise and any other systematic fitness activities. Test equipment and analysis system: ECG recorder (provided by the 4th Research Institute of Air Force), dedicated analysis software (provided by Scientific Research Department of GASC Health Qigong Administration Center), SHENFENG disposable ECG electrode (produced by Shanghai Shenfeng Medical & Health Articles Co., Ltd.)

(1) Specification load test
Preparation: sternal angle (negative pole), xiphoid (reference pole), intersection of left costal inferior margin and anterior axillary line (positive pole) were pasted and connected with ECG recorder by wires to test ECG electrode; put the ECG recorder in specially prepared small bag and fastened at the waist.
Test: the test objects sit quietly and leisurely to perform the following seven consecutive segments of tests:
①
②
③
④
⑤
⑥
⑦
Segments ①⑦: sit quietly and leisurely for ten minutes with background music;
Segments ②⑥: sit and stand movement for five minutes under the guidance of metronome rhythm (20beats/minute);
Segments ③⑤: sit quietly and leisurely for five minutes with background music;
Segment④: sit on the chair and do deep breathing for five minutes (12beats/minute) according to the word of command.

(3) Test during practicing process
Preparation: same as the specification load test.
Test: the test objects sit quietly and leisurely to perform the following three consecutive segments of tests:
Segment ①③: sit quietly and leisurely for 15 minutes with background music;
Segment ②: With the music accompaniment of Health Qigong • Yi Jin Jing, practice Health Qigong • Yi Jin Jing exercise for about 12 minutes.

(3) Data processing
Take out SM card of ECG recorder, import the data into the computer through a card reader, and conduct data pretreatment by use of dedicated analysis software. SPSS10.0 statistical software was used to analyze and process the data. The difference tests between intra-group and inter-group were carried out based on the test results of experimental group and control group taken before and after the experiment.

8.2.2 Results

8.2.2.1 Specification load experiment
(1) time-domain analysis
①Comparison of R-Rmean value between two groups
R-Rmean value reflects the time interval between two adjacent R waves and the reciprocal of R-R interval is the real-time heart rate. As we can be seen from Table 8.2-1 that, the R-Rmean value of experimental group before experiment was higher than that of the control group. That’s because the experimental group has carried out ten months of exercises and the heart rate of practicers after exercise was significantly slower than those people who haven’t participate in the exercise. The R-Rmean values before, during and after experiment were observed and that the experimental group showed
high-low-high trends, which indicated that the heart rate can be quickly returned to the normal level after termination of specification load; while the control group showed high-low-low trends, which indicated that the heart rate was still accelerated after termination of specification load, the variation trend of two groups was significantly different.

Table 8.2-1 Comparison of R-Rmean Value between Two Groups (ms, x ± s )
Groups Before experiment During experiment After experiment
Experimental Group
n=37
821.15±83.89 688.67±73.62 709.53±83.86
Control Group n=27 770.71±95.83 635.63±68.60 619.31±75.85
Note: “before experiment” refers to the sit-quietly stage before specification load, “during experiment” refers to exercise stage of specification load, “after
experiment” refers to sit-quietly stage after specification load, similarly hereinafter. Analyze Table 8.2-1 and choose the difference of R-Rmean before and during experiment and the difference of R-Rmean during and after experiment to reflect the variation trend of R-Rmean in specification load experiment.
It can be seen from Table 8.2-2 that the differences before and during experiment of the two groups were positive values, which indicated that the heart rate was accelerated when the body changed from static to dynamic, and there was no significant difference between two groups (t=0.184,P＞0.05); the differences during and after experiment were negative values for experimental group and positive values for control group, which indicated that the heart rate of experimental group recovered rapidly when the body changed from dynamic to static and the heart rate of control group was accelerated, the recovery of heart rate was lagged behind, and there was significant difference between comparison of two groups (t=4.20,P＜0.05).

Table 8.2-2 Variation Trend of R-Rmean Value between Two Groups (ms, x ± s )
D-value Experimental Group n=37 Control Group n=27 t
Difference before and during experiment
132.48±49.62 135.08±63.61 0.184
Difference during and after experiment
-20.86±28.64 16.32±42.21 4.20**
Note: * represents P＜0.05, ** represents P＜0.01, similarly hereinafter.
② Test result of root mean square of successive difference (RMSSD) during R-R interval of two groups

It can be from Table 8.2-3 that, RMSSD value of the experimental group remained relatively stable during experiment and the difference was not obvious while the control group has an obvious downward trend. The RMSSD value of the two groups has no obvious difference before experiment (P ＞ 0.05), has a certain difference during experiment (P＞0.05) and has obvious difference after experiment (P＜0.05).

Table 8.2-3 Comparison of RMSSD Value between Two Groups (ms, x ± s )
Experimental processes Experiment Group
n=37
Control Group n=27 t
Before experiment 21.93±9.67 24.60±18.39 0.75
During experiment 21.30±12.88 17.93±8.17 1.19
After experiment 23.34±16.00 12.24±6.82 3.38**
③ Test result of coefficient of variation (CV) during R-R interval of two groups
CV is the ratio of standard deviation and mean value, CV values of the two groups in Table 8.2-4 have no significant difference before, during and after experiment (P＞0.05). This may have certain relations with that the experimental group has carried out ten months of exercise, although the standard deviation variation of the experimental group was greater than that of the control group, the mean value of the experimental group was also greater than that of the control group synchronously.

Table 8.2-4 Comparison of CV Value between Two Groups (%, x ± s )
Practicing processes Experimental
Groupn=37
Control Group n=27 t
Before experiment 4.21±1.24 4.36±2.45 0.32
During experiment 16.04±4.16 15.12±3.40 0.94
After experiment 14.46±4.98 13.66±4.20 0.68

(2) Frequency domain analysis
① Test result of normalization low frequency power of two groups
Low frequency power reflects sympathetic nerve modulation intensity. Table 8.2-5 showed that the normalization low frequency power value of the control group before, during and after experiment was from low to high and then increased slightly, there were significant differences in the comparison before and during experiment and the comparison before and after experiment(P ＜ 0.05). The normalization low frequency power value was increased significantly, indicating sympathetic nerve tension kept rising, the inhibition of parasympathetic nerve against sympathetic nerve was insufficient and the heart rate continued to accelerate. The normalization low frequency power value of the experimental group before, during and after experiment was from low to high and then dropped slightly, and the comparison of three sets of data has no significant difference (P ＞ 0.05), indicating the enhancement of sympathetic nerve tension of the experimental group during specification load exercise was not so evident as the control group, and the sympathetic nerve tension of the experimental group was weakened due to the reciprocal inhibition of parasympathetic nerve during the recovery process after exercise and the heart rate was gradually recovered.

Table 8.2-5 Comparison of Normalization Low Frequency Power Value of Two
Groups (ms2,x ± s )
Groups
Before experiment
During experiment
After experiment
t1 t2 t3
Experimental Group n=35 54.32±19.48 61.68±15.74 60.64±20.02 1.79 0.25 1.38
Control Group n=27 55.63±19.75 67.18±18.48 68.07±22.14 2.22* 0.16 2.18*
Note: t1 represents the comparison before and during experiment, t2 represents
comparison during and after experiment, t3 represents comparison before and after
experiment, similarly hereinafter.
② Test result of normalization high frequency power of two groups
High frequency power reflects vagus nerve modulation intensity. Table 8.2-6 showed that the normalization high frequency power value of the control group before, during and after experiment was from high to low and then decreased slightly, there were significant differences in the comparison before and during experiment and the comparison before and after experiment(P ＜ 0.05). The normalization high frequency power value was decreased gradually, indicating the vagus nerve tension was decreased due to the reciprocal inhibition of rising sympathetic nerve tension and the heart rate was accelerated accordingly. The normalization high frequency power value of the experimental group before, during and after experiment was from high to dropped slightly
and then recovered slightly, and the comparison of three sets of data has no significant difference (P＞0.05). The normalization high frequency power value maintained a better stability at a higher level, which indicated that the experimental group has stronger ability in vagus nerve modulation.

Table 8.2-6 Comparison of Normalization High Frequency Power Value of Two
Groups (ms2,x ± s )
Groups
Before experiment
During experiment
After experiment
t1 t2 t3
Experimental Group n=35 45.69±19.48 38.32±15.74 39.36±20.02 1.79 0.25 1.38
Control Group n=27 44.37±19.75 32.83±18.48 31.93±22.14 2.22* 0.16 2.18*
③ Test result of High-frequency Band Peak Position (HP) of Two Groups HP is related with respiratory rhythm, HP value is equivalent to respiratory rate per
second. Table 8.2-7 showed that the HP value of the control group was increased significantly, the comparison before and after experiment and the comparison during and after experiment have very significant differences (P＜0.01), the significant increase of HP value indicated that the respiration was accelerated sharply. The HP value of the experimental group was relatively stable, which indicated that the respiration was steady.

Table 8.2-7 Comparison of HP Value between Two Groups (ms2, x ± s )
Groups
Before experiment
During experiment
After experiment
t1 t2 t3
Experimental Group n=35 0.263±0.061 0.264±0.063 0.272±0.075 0.07 0.50 0.57
Control Group n=27 0.263±0.066 0.261±0.076 0.314±0.068 0.10 2.70** 2.80**

8.2.2.2 Test during exercise
We conducted heart rate variability (HRV) test for the experimental group during Health Qigong • Yi Jin Jing exercise to observe the dynamic changes of HRV before, during and after exercise.

(1) Time-domain analysis
Table 8.2-8 showed that the R-Rmean value revealed a large-small-large trend before, during and after exercise, there were very significant differences in the comparison before and during exercise and the comparison during and after exercise, and there was no significant difference in the comparison before and after exercise. RMSSD value was stable at a higher level, and there was no significant difference in comparison with each other. CV value showed a trend of small-large-fall back, there was very significant difference in comparison with each other.

Table 8.2-8 Time-domain Analysis Result of HRV Test during Exercise
(n=33, x ± s )
Test items Before practice During practice After practice t1 t2 t3
R-Rmean(ms) 835.76±140.00 659.29±91.14 800.11±112 6.07** 5.60** 1.14
RMSSD(ms2) 21.93±13.19 18.95±12.85 20.12±11.73 0.93 0.39 0.59
CV(%) 4.33±1.53 9.26±2.69 5.81±1.67 9.26** 6.26** 3.75**

It is generally acknowledged that the target heart rate of the old and middle-aged people who participate in aerobic fitness exercise is 60~80% of the maximum heart rate and there will be certain risks over this range. It can be seen from Table 8.2-8 that, R-Rmean value before, during and after exercise conversed into heart rate were 72, 91 and 75 (beats/minute), the average heart rate during exercise was 91beats/minute, which can achieve effective fitness heart rate and have good security. The heart rate of the experimental group after exercise can be recovered to the level almost same as that before exercise rapidly, RMSSD value was stable at a higher level, indicating that the practicers have stronger ability in vagu nerve modulation.

(2) Frequency domain analysis
Table 8.2-9 showed that the normalization LF value revealed a trend of low-high-fall back and normalization HF value revealed a trend of high-low-fall back during the experiment, there was very significant differences in the comparison before and during experiment and the comparison during and after experiment, and there was no significant difference in the comparison before and after experiment. HP value was relatively stable during experiment and there was no significant difference in comparison with each other. These results showed that the excitability of sympathetic nerve during exercise was
significantly strengthened with the start of exercise, the vagus nerve tension was decreased due to the inhibition, the heart rate was accelerated and the respiratory acceleration was not obvious. When the exercise stops, the vagus nerve immediately played stronger modulation effect, the excitability of sympathetic nerve was inhibited, the heart rate recovered to normal level in a short time and the respiration remained stable.

Table 8.2-9 Frequency Domain Analysis Result of HRV Test during Exercise
(n=34, x ± s )
Before practice During practice After practice t1 t2 t3
Normalization LF  55.61±20.13 80.35±12.07 60.22±16.84 6.15** 5.67** 1.02
Normalization HF  44.39±20.13 19.50±12.00 39.77±16.85 6.19** 5.71** 1.03
HP 0.258±0.065 0.224±0.088 0.261±0.071 1.81 1.91 0.18

8.2.3 Discussions
Heart rate variability (HRV) refers to the degree of fluctuation variation of sinus heart rate, which is one of non-invasive ECG monitoring indicators that have been widely concerned in recent years. It is generally believed that cardiac rhythm is directly subject to double regulation and mutual restriction of cardiac sympathetic nerve and cardiac vagus nerve, the vagus nervous system is restricted while the sympathetic nervous system is excited, and the heart rate and respiration are accelerated; the sympathetic nervous system is restricted while the vagus nervous system is excited, the heart rate and respiration are slowed down, the sympathetic nervous system interacts with the vagus nervous system and results in irregular heart rate changes. Therefore, HRV is considered as an important indicator of evaluating the functions of autonomic nervous system [4].

This topic made a study on the heart rate variability (HRV), although the ECG data of two groups were not recorded at the beginning of this study (before the experiment), the HRV test adopted specification load experiment to enable the research experimental subjects to observe HRV variations in static – dynamic (specification load) – static. The principle of specification load experiment is same as ECG exercise test (ET) that has been widely used in clinical medicine. In the experiment, the demands of individual cardiac muscle on blood and oxygen were increased, especially the coronary artery vascular decompensation caused myocardial ischemia and anoxic at blood-supply parts, the balance of cardiac autonomic nervous regulation was changed, and the regulation effect on the heart was weakened, HRV was declined. The more significant the HRV decrease, the worse the disease will be [5] [6].

The study results showed that there was significant difference in HRV between the two groups, the R-Rmean value of the control group was further decreased after specification load exercise, LF and HP values were increased, and RMSSD and HF values were fallen back significantly before, during and after specification load exercise. The results were in line with HRV of ordinary healthy old and middle-aged people [1] [2]. Thus it can be seen that the sympathetic nervous system of the control group after specification load exercise remained higher tension and the vagus nerve cannot play a significant role in modulation within a short period. The R-Rmean value of the experimental group after specification load exercise can be close to normal level rapidly, LF value was fallen down rapidly and the heart rate snapped back to normal; RMSSD, HF and HP values remained stable and the respiration was stable before, during and after specification load exercise, the vagus nervous system tension of the practicers maintained a higher level, the excitability of vagus nervous system was reduced due to the restriction of vagus nerve when the specification load exercise stops, thereby increasing the stability of ECG, improving myocardial ischemia hypoxia, and reducing the occurrence of high blood pressure, atherosclerosis and other diseases[7].

Health Qigong•Yi Jin Jing is an aerobic fitness exercise characterized by “muscle-stretching and bone-pulling effect, guiding Qi with form, relaxed movements, mind follows the movements, breathe naturally, soft and smooth”. The average heart rate of 91beats/minute (reciprocal of R-Rmean value) during exercise was just achieved the target heart rate range of aerobic fitness exercise of the old and middle-aged people.

Health Qigong•Yi Jin Jing and Tai Chi Chuan, treadmill exercise and other traditional sports are medium amount of exercises [1] [8], which have good adaptability for the old and middle-aged people. Viewing from the results that RMSSD value remained stable at a higher level, normalization HF value was recovered rapidly and HP value maintained stable, after ten months of Health Qigong • Yi Jin Jing exercise, the vagus nerve tension of the practicers maintained a higher level, the regulation action of autonomic nervous system was strengthened markedly, and the physical quality was improved significantly.
Due to the small sample size of this study, some other indicators of HRV showed larger standard deviations that were unsuitable for analysis, which should be further studied by expanding sample size.

References

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