| Research purposes: Physiological parameters such as heart rate,blood pressure,and heart rate variability are external manifestations of the stress response.These parameters will change with the stress status,which can objectively and truly reflect the current individual stress status.The "point" results of physiological parameters,which is the difference between pre-stress data and post-stress data,can identify the stress status.However,combing the "point" results with the dynamic magnitude of changes in physiological parameters can assess stress levels in a more comprehensive way.The stressors encountered by police officers at work are complex and diverse.Different stressors have different levels of stress responses.Therefore,on the basis of accurately detecting the changes of physiological parameters in different stress states,this paper hopes to comprehensively evaluate the performance of police in different stress sources by comparison of "point" physiological parameter results and by comparison of stress physiological parameter results and magnitude of changes with normal range.The paper also proposes more targeted and single-police-operable stress-intervention countermeasures based on different physiological responses,so that the related psychological rehabilitation methods can be more effective to improve the police’s mental health.Research methods: The research of this paper involves three stages,corresponding to Study I,Study II and Study III respectively.Study I and Study II provide the basis for the development of Study III.Specifically,Study I is to delineate the normal reference values of physiological parameters,which provides a comparison standard for Study III;Study II is to screen the stressors of police work,which provides effective stress materials for Study III;Study III is to explore the changes of physiological parameters with exposures to different stressors.Study Ⅰ and Ⅲ selected 31 current graduate student police officers as experimental participants,collected data using Ergo LAB physiological recording bracelets,analyzed them through a synchronized cloud platform system to derive heart rate and heart rate variability indicators,and used Omron blood pressure monitors to collect blood pressure indicators from the participants.Study I divided the waking hours of a day（from 8:00 am to 10:00 pm）into seven time periods,and measured physiological data every two hours.By measuring the physiological parameters（heart rate,heart rate variability,and blood pressure）of the 31 participants during the waking hours of the day,the normal range of fluctuation of physiological parameters of the 31 participants was delineated to provide criteria for studying the changes of physiological parameters in stress status for Study III.Study II firstly used the interview method to interview 18 grassroots civilian police officers from the front line,summarized the mentioned stressors,and screened the three stressors that appeared most frequently in their work and life.Next,laboratory stress materials were screened to simulate work stressors.Combined with the interviews,the stress materials were determined by the changes in blood pressure and heart rate indicators of another 12 civilian police officers.In Study III,on the basis of Study 1 and Study II,the stress materials from Study II were used to induce different stress status in the participants,the effects of the three stress sources of mental arithmetic,video,and speech on various physiological parameters of the participants were observed,and the changes of pointlike physiological indicators were combined with the dynamic fluctuation amplitude to jointly assess the stress status.By analyzing different physiological responses,targeted stressintervention countermeasures were proposed.Research results: In Study I,The normal reference ranges for the values of the physiological parameters derived in Study I were as follows: heart rate（71.06 to 83.13beats/min）,IBI（723.10 to 846.17 ms）,SDNN（69.44 to 89.98 ms）,RMSSD（73.88 to 95.47）,p NN50（37.96% to 47.58%）,LF（32.45% to 41.43%）,HF（33.04% to 42.29%）,LF/HF（0.80 to1.62）,systolic blood pressure（109.33 to 123.87 mm Hg）,diastolic blood pressure（66.83 to76.39 mm Hg）,and pulse pressure difference（39.66 to 45.61 mm Hg）.The calculated maximum magnitudes of changes in physiological parameters: 17.04% for both indicators heart rate and IBI;29.73%,29.35% and 25.46% for SDNN,RMSSD and p NN50 respectively;27.74% and28.25% for LF and HF respectively;13.43%,14.48%,and 15.06% for blood pressure indicators systolic blood pressure,diastolic blood pressure,and pulse pressure difference respectively.In Study Ⅱ,Three stressors（leaders’ command and evaluation of work;paperwork materials processing;possible sources of danger in cases）occurred most frequently in police work in Study 2.Considering these three stressors,three stress materials（a speech task;a mental arithmetic task;a video task）were selected.In Study Ⅲ,when in the stress status,the participants showed significant changes in various physiological parameters compared to the preparatory period,with significant increases in heart rate,LF,LF/HF,and blood pressure indicators and significant decreases in IBI,HRV time domain indicators and HF.In cardiac calculation stage 1,except for the index SDNN,the mean values of all the indexes were within the reference range of normal values.Besides,only the change in p NN50 was slightly greater than the maximum value.In the cardiac calculation stage 2,only the mean values of HF and pulse pressure difference were within the reference range of normal values,and the variation of IBI,p NN50 and LF was greater than the maximum variation.In the video stress task,the values of HRV frequency domain indicators and pulse pressure difference were within the normal range;the changes in p NN50,systolic blood pressure,and diastolic blood pressure were greater than the maximum change.In the speech stress status,except for the LF,the values of physiological parameters are beyond the normal range values.The amplitude of the rest of the indicators is greater than the maximum change amplitude,while SDNN and LF indicators of change amplitude are within the normal range of amplitude.Research conclusions: firstly,affected by environmental changes and biological rhythms,the individual physiological parameters remain a dynamic balance within a certain range.Secondly,since physiological parameters change,the homeostasis of the autonomic nervous system is affected,sympathetic and parasympathetic activity are altered,and the sympathetic nervous system dominates under stress.Thirdly,the effects of different stressors on physiological parameters vary.Heart calculation has a greater effect on HRV time domain indicators（SDNN）and frequency domain（LF）,and shortening the cardiac cycle will lead to enhanced sympathetic activity;the video task has a greater effect on blood pressure indicators,enhanced contraction of vascular smooth muscle will lead to increased blood pressure,affecting the function of the cardiovascular system;the range of changes in all physiological parameters under the speech task is large,but the changes in HF in the HRV frequency domain indicators are more pronounced,indicating that the speech changes in all physiological parameters under the speech task were significant,but the changes of HF in the HRV frequency domain index were more pronounced,indicating a greater inhibitory effect of the speech task on parasympathetic activity.Fourthly,more targeted interventions can be proposed for different stress responses.Progressive muscle relaxation training can be used for excessive sympathetic activity,autogenic training intervention can be used for excessive changes in blood pressure indexes,orthostatic training intervention countermeasures can be used for diminished parasympathetic activity,and anticipatory intervention strategies can be used for stress reactions before stress occurs. |
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