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Effects of Autogenic Training on Stress Response and Heart Rate Variability in Nursing Students

Open AccessPublished:November 03, 2014DOI:https://doi.org/10.1016/j.anr.2014.06.003

      Summary

      Purpose

      This study was undertaken to confirm the effects of autogenic training (AT) on stress response and heart rate variability in nursing school students experiencing stress related to clinical training.

      Methods

      The study was carried out from September 2012 to April 2013 in a quasi-experimental nonequivalent control group using a pretest-posttest design. The participants were 40 nursing students in their third year at either of two nursing colleges. All consented to participate. Nineteen nursing students at one college were assigned to the experimental group and underwent the 8-week AT program, and the other 21 were assigned to the control group and did not undergo any training. Stress response was assessed by questionnaire and HRV was measured three times, that is, before the program, at the end of the program, and 6 months after the end of the AT program.

      Results

      A significant time/group interaction was found for stress response (F = 4.68, p = .012), a subjective indicator. However, no significant interaction was found for the objective indicators of heart rate variability, normalized low frequency (F = 2.59, p = .090), normalized high frequency (F = 2.59, p = .090), or low frequency to high frequency ratio (F = 1.38, p = .257).

      Conclusion

      The results suggest that AT provides an acceptable approach to stress reduction in nursing students.

      Keywords

      Introduction

      Nursing school students are under more stress than students studying other majors because of the burden imposed by taking courses while completing clinical training, which accounts for a large proportion of academic credits (
      • Yoo J.S.
      • Chang S.J.
      • Choi E.K.
      • Park J.W.
      Development of a stress scale for Korean nursing students.
      ). In particular, nursing students experience much more stress during initial clinical training. The sources of stress for these students are mainly the result of a lack of professional knowledge and skills in taking care of patients, the clinical environment, and teachers and nursing staff (
      • Chan C.K.L.
      • So W.K.W.
      • Fong D.Y.T.
      Hong Kong baccalaureate nursing students' stress and their coping strategies in clinical practice.
      ,
      • Shaban I.A.
      • Khater W.A.
      • Akhu-Zaheya L.M.
      Undergraduate nursing students' stress and coping behaviors during their initial period of clinical training: a Jordanian perspective.
      ,
      • Sheu S.
      • Lin H.S.
      • Hwang S.L.
      Perceived stress and physio-psycho-social status of nursing students during their initial period of clinical practice: the effect of coping behaviors.
      ). Furthermore, they have only knowledge of basic medicine and nursing prior to clinical training (
      • Sheu S.
      • Lin H.S.
      • Hwang S.L.
      Perceived stress and physio-psycho-social status of nursing students during their initial period of clinical practice: the effect of coping behaviors.
      ). Accordingly, they do not know how to cope with the dynamic and complex clinical environments, how to establish good relationships with clinical staff and instructors or deal with sudden changes in patients' conditions (
      • Elliott M.
      Clinical environment: a source of stress for undergraduate nurses.
      ). This stress has a negative effect on adaptation to clinical training, and thus, on student health. Furthermore, if stress is excessive or prolonged, nursing students fail to adapt to clinical training (
      • Park H.M.
      • Ha N.S.
      • Choi J.
      The effects of guided imagery on the stress and anxiety of nursing students in clinical practice.
      ) and experience psychological difficulties, such as anxiety, a sense of anger, indifference, frustration, and depression (
      • Chang S.B.
      • Kim S.Y.J.
      • Oh G.S.
      • Yoo I.Y.
      • Kim H.S.
      • Kim S.A.
      • et al.
      The effects of guided imagery program on high school male students' stress, stress coping, and health problem.
      ), and physical health problems, such as indigestion, anorexia, backache, headache, and insomnia (
      • Choo S.H.
      • Ha E.H.
      • Lee B.O.
      • Chun D.I.
      • Kim Y.H.
      • Song D.H.
      The physical and mental symptoms of normal subjects with mild life stress.
      ,
      • Park J.W.
      • Ha N.S.
      Nursing students' clinical experiences.
      ).
      As social concerns regarding health have increased, the need for diverse teaching methods to provide qualified nursing care skills has been suggested (
      • Whang S.J.
      The relationship between clinical stress, self-efficacy, and self-esteem of nursing college students.
      ). Thus, as the importance of clinical training increases, nursing students need appropriate stress coping strategies to reduce the risks of physical and mental health problems.
      Relaxation training provides an excellent strategy for managing stress, and autogenic training (AT) is one type of this training (
      • Kanji N.
      • White A.
      • Ernst E.
      Autogenic training to reduce anxiety in nursing students: randomized controlled trial.
      ,
      • Son C.N.
      Behavioral relaxation training and behavioral relaxation assessment.
      ). AT is a psychophysiological type of psychotherapy based on autosuggestion, first developed by the German physician and psychiatrist J.H. Schultz in the early 20th century. AT consists of the phased practice of six simple relaxation responses. The first exercise that addresses muscular relaxation is performed by reiterating a formula to promote a sensation of heaviness in limbs, and subsequently, attention is focused inactively on sensing warmth, then on slow breathing, abdominal warmth, a calm heart beat, and a cool forehead. It has been recommended that the AT program be conducted over 8 weeks and that it be composed of one group session per week and self-training three times daily (
      • Kanji N.
      • White A.
      • Ernst E.
      Autogenic training to reduce anxiety in nursing students: randomized controlled trial.
      ,
      • Rhee J.H.
      Manual for AT-facilitator, facilitating autogenic training.
      ). While progressing through these exercises, most people experience passive concentration, which allows the individual to break out the vicious stress cycle (
      • Carruthers M.
      Autogenic training.
      ). AT leads a high-arousal sympathetic nervous response to low-arousal parasympathetic nervous response via relaxation (
      • Kanji N.
      • White A.
      • Ernst E.
      Autogenic training to reduce anxiety in nursing students: randomized controlled trial.
      ,
      • Rhee J.H.
      Manual for AT-facilitator, facilitating autogenic training.
      ).
      Some reports have claimed that AT has valuable effects on the mind and body, and is currently used to treat diseases related to or aggravated by stress, such as irritable bowel syndrome (
      • Shinozaki M.
      • Kanazawa M.
      • Kano M.
      • Endo Y.
      • Nakaya N.
      • Hongo M.
      • et al.
      Effect of autogenic training on general improvement in patients with irritable bowel syndrome: a randomized controlled trial.
      ), cancer (
      • Wright S.
      • Courtney U.
      • Crowther D.
      A quantitative and qualitative pilot study of the perceived benefits of autogenic training for a group of people with cancer.
      ), and multiple sclerosis (
      • Sutherland G.
      • Andersen M.B.
      • Morris T.
      Relaxation and health-related quality of life in multiple sclerosis: the example of autogenic training.
      ). AT is also used to treat stress. Three trials have been performed to study the effect of AT on stress in nursing students, which found that AT reduced anxiety (,
      • Kanji N.
      • White A.
      • Ernst E.
      Autogenic training to reduce anxiety in nursing students: randomized controlled trial.
      ) and the absence rate due to illness (
      • Bailey R.D.
      Autogenic regulation training and sickness absence amongst student nurses in general training.
      ).
      Stress is known to affect cardiovascular changes, which are usually related to autonomic nervous system activity changes (
      • Rozanski A.
      • Bairey C.N.
      • Krantz D.S.
      • Friedman J.
      • Resser K.J.
      • Morell M.
      • et al.
      Mental stress and the induction of silent myocardial ischemia in patients with coronary artery disease.
      ). Heart rate variability (HRV) is one of the indicators of changes in the autonomic nervous system (
      • Chandola T.
      • Heraclides A.
      • Kumari M.
      Psychophysiological biomarkers of workplace stressors.
      ), and has been used to measure general autonomic system function and physiological stress response degree because of its simplicity and noninvasive nature (
      • Sztajzel J.
      Heart rate variability: a noninvasive electrocardiographic method to measure the autonomic nerve system.
      ,
      • Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology
      Heart rate variability: standards of measurement, physiological interpretation and clinical use.
      ).
      • Mitani S.
      • Fujita M.
      • Sakamoto S.
      • Shirakawa T.
      Effect of autogenic training on cardiac nervous activity in high-risk fire service workers for posttraumatic stress disorder.
      measured changes in stress and autonomic nervous activity using HRV, and reported that sympathetic nervous activity increases but parasympathetic nervous activity decreases in stressful situations.
      • Pomeranz B.
      • Macaulay R.J.
      • Caudill M.A.
      • Kutz I.
      • Adam D.
      • Gordon D.
      • et al.
      Assessment of autonomic function in humans by heart rate spectral analysis.
      concluded that HRV is a credible and sensitive indicator of cardiac autonomic nervous activity through HRV power spectral analysis.
      Studies on AT have been performed over many years overseas, but little work has been undertaken in Korea. In particular, few studies have been conducted on the AT Korean Standard developed by Ju-hee Rhee based on the original AT by Schultz (
      • Rhee J.H.
      Is Korea burning out? The autogenic training as the proper solution.
      ,
      • Rhee J.H.
      Manual for AT-facilitator, facilitating autogenic training.
      ). Few HRV studies have evaluated the effects of AT.

      Purpose of study and hypotheses

      This study was undertaken to confirm the effects of AT on stress response and HRV in nursing school students experiencing stress related to clinical training. We hypothesized stress response in the experimental group, members of which were administered with AT, would be lower than that in the control group, and that normalized low frequency (LF) would be lower, normalized high frequency (HF) would be higher, and LF/HF ratio would be lower in the experimental group.

      Methods

      Study design

      This study used a quasi-experimental, nonequivalent control group, pretest-posttest design (19 participants in the experimental group, 21 participants in the control group). Participants in the experimental group were administered the AT Korean Standard. Outcomes were measured three times: before the AT program, at the end of the standard 8-week program, and at 6 months after the end of the program.

      Setting and samples

      The participants were 40 nursing students in their third year at two nursing colleges. All consented to participate. Nineteen nursing students at one college were assigned to the experimental group and underwent the 8-week AT program, and the other 21 were assigned to the control group, members of which did not undergo any training. No participant dropped out of the study. The sample size for this study was calculated before the investigation. G*power program, version 3 (
      • Faul F.
      • Erdfelder E.
      • Lang A.G.
      • Buchner A.
      G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences.
      ) showed that 16 students per group were required for an effect size of 0.3, at a power of 95%, and an alpha level of .05. The reasons why we decided on this small effect size were that no previous AT study has calculated sample size using the G*power program and the experimental and control groups were well matched. The selection criteria were as follows: (a) agreement to participate in the study; (b) no relaxation therapy during the previous 6 months; and (c) no cardiovascular or neurological problem.

      Ethical considerations

      This study was approved by the institutional review board of Hoseo University (approval no.: 20120009). Participants interested in this study voluntarily participated in the program. The study purposes and procedures were explained to participants. Participants were told that personal information would be protected and they could drop out of the study without prejudice at any time. Participants provided written informed consent and were briefed beforehand on study purposes and procedures, anticipated risks and benefits, privacy protection, compensation methods, and withdrawal from the study.
      Due to their student statuses, honest answers of the participants were emphasized to avoid ethical problems during the study. In particular, the risk of making false or flattering responses by students were prevented by informing them that honest answers could enhance the quality of the study. Furthermore, participants were told that all collected data would be used for study purposes only.

      Intervention

      Autogenic training

      AT was administered according to the AT Korean Standard (Table 1) in a lecture room by an AT facilitator certified by the Korean AT Association. AT involved the phased practice of 6 simple relaxation responses once weekly for 8 weeks. In a relaxed sitting position with eyes closed, the training involved the use of six short verbal standard formulae. The first exercise targeted muscular relaxation. The principle subject of the verbal formula used was heaviness. Right-handed students started passive concentration of “My right arm is heavy,” whereas left-handed participants started with the left arm. The second mandatory passive concentration addressed peripheral warmth using formula “My right/left arm is warm.” After learning to generate feelings of heaviness and warmth, participants were taught to concentrate on breathing, which was keyed by the instruction “My breathing is calm and regular,” and then to warm the abdominal region by using the formula “My solar plexus is warm.” The following exercise concerned the cranial region, which should be cooler than the rest of the body. Here, the formula used was “My forehead is cool.” Finally, the focus was placed on cardiac activity with the formula “My heart beat is calm and regular.” Each formula was practiced in group sessions and participants were asked to practice the learned autogenic exercises alone at least twice daily. In addition, they were asked to submit a report of their experiences and any questions regarding their experiences while they practiced the exercises. At each of the 8 sessions, the facilitator provided feedback to the participants based on considerations of these reports. If a student found it difficult to practice the exercises alone, the facilitator encouraged them to find solutions and made suggestions. Detailed contents of AT for nursing students are provided in Table 1.
      Table 1Summary of Korean Standard Autogenic Training Program.
      8-week sessionsExercise formulaeContents
      1My right/left arm is heavy.Explain the principles of AT and the necessity of self practice

      Practice the first standard procedure using the first formula, “My right/left arm is heavy.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      2My right/left arm is warm.Discuss self practice

      Review the first standard procedure

      Practice the second standard procedure using the second formula, “My right/left arm is warm.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      3My breathing is calm and regular.Discuss self practice

      Review the first two standard procedures

      Practice the third standard procedure using the third formula, “My breathing is calm and regular.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      4Review the three procedures.Discuss self practice

      Review and practice the first three standard procedures

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      5My solar plexus is warm.Discuss self practice

      Review the first three standard procedures

      Practice the fourth standard procedure using the fourth formula, “My solar plexus is warm.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      6My forehead is cool.Discuss self practice

      Review the first through fourth standard procedures

      Practice the fifth standard procedure using the fifth formula, “My forehead is cool.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      7My heart beat is calm and regular.Discuss self practice

      Review the first through fifth standard procedures

      Practice the sixth standard procedure and formula, “My heart beat is calm and regular.”

      Solve problems, support, and encourage by feedback

      Give materials for self practice and explain self practice
      8Final checkDiscuss self practice

      Review and practice the six standard procedures

      Solve problems, support, and encourage by feedback

      Advise regarding further training: once a day for a year

      Instruments

      Stress response

      Stress response is a measure of the physical and mental reactions caused by stress. In this study, it refers to the score on the scale developed by
      • Koh K.B.
      • Park J.K.
      • Kim C.H.
      Development of the stress response inventory.
      . Permission to use this scale was acquired from
      • Koh K.B.
      • Park J.K.
      • Kim C.H.
      Development of the stress response inventory.
      , after providing an explanation of the study purpose. This 39-item scale has seven subscales: tension, aggression, somatization, anger, depression, fatigue, and frustration, which are each scored on a 5-point scale. A higher score means a greater stress response. Cronbach's alpha as determined by Koh et al. was .97. In the present study it was .92.

      HRV

      HRV was measured by emWavePSR (HeartMath, Inc., CA, USA) for 5 minutes, and MATLAB program (The MathWorks, Inc., Kuopio, FINLAND) with Kubios HRV version 2.0 was used to obtain the indicators for frequency-domain analysis. This analysis entails the distribution of oscillations in three frequency bands and the determination of power in each of these bands (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, 1996). Power in the HF band (0.15–0.4 Hz) is an indicator of parasympathetic nervous activity, whereas power in the LF band (0.05–0.15 Hz) mostly reflects sympathetic nervous activity (
      • Song B.A.
      • Yoo S.Y.
      • Kang H.Y.
      • Byeon S.H.
      • Shin S.H.
      • Hwang E.J.
      • et al.
      Post-traumatic stress disorder, depression, and heart-rate variability among North Korean defectors.
      ). Power in the very-low-frequency (VLF) band (0.005–0.05 Hz) is an additional indicator of parasympathetic nervous activity (
      • Pagani M.
      • Lombardi F.
      • Guzzetti S.
      • Rimoldi O.
      • Furlan R.
      • Pizzinelli P.
      • et al.
      Power spectral analysis of heart rate and arterial pressure variability as a marker of sympato-vagal interaction in man and conscious dog.
      ). LF/HF ratio is a general balance indicator used to evaluate sympathetic/parasympathetic nervous system balance. A high ratio implies intensified activity of the sympathetic nervous system or suppression of the parasympathetic nervous system (
      • Mellman T.A.
      • Knorr B.R.
      • Pigeon W.R.
      • Leiter J.C.
      • Akay M.
      Heart rate variability during sleep and the early development of posttraumatic stress disorder.
      ).
      In this study, normalized LF, normalized HF, and LF/HF ratio were used to analyze autonomic nervous system activity. The formula used to calculate normalized LF or HF was as follows: normalized LF or HF = (LF or HF/total power − VLF) × 100 (
      • Dishman R.K.
      • Nakamura Y.
      • Garcia M.E.
      • Thompson R.W.
      • Dunn A.L.
      • Blair S.N.
      Heart rate variability, trait anxiety, and perceived stress among physically fit men and women.
      ).

      Data collection

      Data was collected from September 2012 to April 2013. AT was conducted for 8 weeks, from September to October 2012. Data collection was performed three times: before AT, at the end of AT, and 6 months after AT completion. To control for factors affecting the autonomic nervous system when HRV was measured, participants were asked not to drink alcohol the night before the examination and not to drink caffeine or smoke for at least 4 hours before the examination. HRV was measured in a quiet, calm conference room. Participants were asked to remove jewelry and cell phones, and to adopt a comfortable posture. After applying the measurement sensor to an ear lobe, the procedure was explained and HRV was measured for 5 minutes while maintaining a respiration rate of 14–20 breaths per minute (
      • Kim S.H.
      • Hwang H.J.
      • Kim J.W.
      • Sim J.Y.
      • Lee H.L.
      The relationship between heart rate variability and severity of disease.
      ).

      Data analysis

      Data analysis was performed using SPSS version 18.0 for Windows (IBM SPSS Statistics, Chicago, IL, USA). Chi-square test, Fisher's exact test, and t test were used for testing homogeneity between the experimental and control groups. Hypothesis testing was performed using repeated measures analysis of variance.

      Results

      Homogeneity testing of participants

      Religion, burden of tuition fees, residence type, motivation for major study, and study satisfaction were similar in the experimental and control groups (Table 2). No significant difference in the total stress response scores or the seven subscales were observed between the two groups (Table 3). Furthermore, the three indicators of HRV, normalized LF, normalized HF, and LF/HF ratio, were not significantly different in the two groups (Table 3).
      Table 2Homogeneity Testing of General Characteristics in the Experimental and Control Groups (N = 40).
      CharacteristicsCategoriesExp (n = 19)Cont (n = 21)χ2p
      n (%)n (%)
      ReligionYes6 (31.6)7 (33.3)0.01.906
      Calculated by χ2-test.
      Burden of tuitionYes7 (36.8)13 (61.9)2.21.113
      Calculated by χ2-test.
      Residence typeWith parents4 (21.1)5 (23.8)1.45.505
      Calculated by Fisher's exact test.
      Dorm13 (68.4)11 (52.4)
      Rented room2 (10.5)5 (23.8)
      Admission motivesInterest9 (47.4)15 (71.4)2.41.121
      Calculated by χ2-test.
      Suggestion10 (52.6)6 (28.6)
      Education satisfactionPositive14 (73.7)18 (85.7)0.90.442
      Calculated by Fisher's exact test.
      So-so5 (26.3)3 (14.3)
      Note. Exp = experimental group; Cont = control group.
      a Calculated by χ2-test.
      b Calculated by Fisher's exact test.
      Table 3Homogeneity Testing of Stress Response and Heart Rate Variability in Experimental and Control Groups (N = 40).
      ValuesExp (n = 19)Cont (n = 21)Total (n = 40)tp
      M ± SDM ± SDM ± SD
      Stress responseTotal68.37 ± 19.3973.05 ± 19.5470.83 ± 19.370.76.453
      Tension9.47 ± 2.5210.29 ± 3.619.90 ± 3.130.82.419
      Aggression4.79 ± 1.135.71 ± 2.354.55 ± 1.010.76.450
      Somatization5.63 ± 2.315.67 ± 2.785.38 ± 1.92−0.97.338
      Anger9.58 ± 3.4710.81 ± 3.3710.23 ± 3.431.14.263
      Depression11.94 ± 3.7212.57 ± 3.5012.23 ± 3.580.64.527
      Fatigue10.47 ± 3.7511.29 ± 4.3910.90 ± 4.070.63.535
      Frustration13.58 ± 5.2514.33 ± 4.9513.98 ± 5.050.47.643
      HRVLF norm43.01 ± 16.1539.40 ± 11.1941.12 ± 13.71−0.83.414
      HF norm57.00 ± 16.1560.60 ± 11.1958.89 ± 13.710.83.414
      LF/HF ratio0.89 ± 0.550.72 ± 0.390.80 ± 0.47−1.19.241
      Note. Exp = experimental group; Cont = control group; HRV = heart rate variability; LF norm = normalized low frequency; HF norm = normalized high frequency.

      Stress response

      Testing of the hypothesis that total stress response score in the experimental group undergoing AT would be lower than in the control group supported the study hypothesis (Table 4). Stress response levels were different in the two groups (F = 7.11, p = .011) and times differed within groups (F = 5.30, p = .007). Furthermore, a significant time/group interaction effect was found on stress response (F = 4.68, p = .012). In the control group, mean stress response score increased by 14.70 points from 73.05 at the end of the AT, and by 20.99 points at 6 months after AT. On the other hand, in the experimental group no significant differences were observed between scores (Figure 1). These results signify that AT reduced stress response.
      Table 4Differences in Stress Response between Experimental and Control Groups (N = 40).
      VariablesExp (n = 19)Cont (n = 21)Between groupWithin group
      GroupTimeTime × group
      M ± SDM ± SDF (p)F (p)F (p)
      Stress response1st68.37 ± 19.3973.05 ± 19.547.11 (.011)5.30 (.007)4.68 (.012)
      2nd68.37 ± 18.9087.71 ± 24.90
      3rd68.00 ± 16.8894.14 ± 30.10
      HRVLF norm (%)1st43.01 ± 16.1639.40 ± 11.190.22 (.643)9.18 (.001)2.59 (.090)
      2nd46.64 ± 17.0740.32 ± 14.82
      3rd49.31 ± 14.2154.39 ± 11.75
      HF norm (%)1st57.00 ± 16.1660.00 ± 11.190.22 (.643)9.18 (.001)2.59 (.090)
      2nd53.36 ± 18.0759.68 ± 14.82
      3rd50.69 ± 14.2145.61 ± 11.75
      LF/HF ratio1st0.89 ± 0.540.72 ± 0.390.47 (.498)7.92 (.001)1.38 (.257)
      2nd0.87 ± 0.460.75 ± 0.40
      3rd1.05 ± 0.481.04 ± 0.38
      Note. Exp = experimental group; Cont = control group; HRV = heart rate variability; LF norm = normalized low frequency; HF norm = normalized high frequency; 1st = before the AT program; 2nd = at the end of the standard 8-week AT program; 3rd = 6 months after the end of the AT program.
      Figure thumbnail gr1
      Figure 1Changes in stress response overtime. Note. Exp = experimental group; Cont = control group; 1st = before the AT program; 2nd = at the end of the standard 8-week AT program; 3rd = 6 months after the end of the AT program.

      HRV

      The hypothesis that the sympathetic nervous activity level (normalized LF) in the experimental group would be lower than in the control group was rejected. There was a significant time difference (F = 9.18, p = .001), but no significant time/group interaction effect was found (F = 2.59, p = .090) (Table 4). The hypothesis that parasympathetic nervous activity level (normalized HF) in the experimental group would be higher than in the control group was also rejected (Table 4). The hypothesis that LF/HF ratio in the experimental group would be lower than in the control group was rejected. There was a significant time difference (F = 7.92, p = .001), but no significant time/group interaction effect was found (F = 1.38, p = .257) (Table 4).

      Discussion

      Several research findings related to the effects of AT training of nursing students to cope with stresses were produced by this study. These outcomes have following implications.
      First, the results of this study are consistent with those of previous studies that focused on the effects of AT. In general, there are two methods of coping with stress, that is, problem-focused methods aimed at solving or changing the problem, and emotion-focused coping methods based on psychological and behavioral efforts (
      • Lazarus R.S.
      • Falkman S.
      Stress, appraisal and coping.
      ). The AT used in this study is a type of emotion-focused coping method.
      • Yurdakul L.
      • Holttum S.
      • Bowden A.
      Perceived changes associated with autogenic training for anxiety: a grounded theory study.
      analyzed the effect of AT by using grounded theory, and presented clear evidence that AT decreased anxiety levels in women by enhancing a sense of well-being in the context of stress management.
      • Kwon Y.S.
      The effect of autogenic training prenatal education to the anxiety, depression and stress of the pregnant woman.
      also reported that AT effectively reduced stress levels in pregnant women. According to a study by
      • Masato M.
      • Kazuyoshi K.
      • Mutsumi A.
      • Toshio M.
      • Mami T.
      • Taisaku K.
      Recent advance of autogenic training in clinical practice of psychosomatic medicine in Japan.
      , AT supported the development of mental energy to create a positive self image and a sense of self efficiency, and reduced patient anxiety levels.
      • Tsutsumi T.
      • Kabeya M.
      • Ogawa K.
      Outcomes of autogenic training for patients with chronic subjective dizziness.
      also reported that AT reduced trait anxiety in patients with chronic subjective dizziness. A meta-analysis of experimental studies by
      • Ernst E.
      • Kanji N.
      Autogenic training for stress and anxiety: a systematic review.
      showed AT had positive effects on relieving stress in seven cases out of eight. In the present study, it was found that stress response levels in the experimental group were lower than those in the control group. This finding demonstrates that the AT program had positive effects on the abilities of nursing students to cope with stress, which is in line with the studies mentioned above.
      Second, this study differs from other studies with respect to the applicability of the relaxation method to university students.
      • Song M.R.
      • Kim S.H.
      The effects of relaxation on stress and blood pressure induced by cognitive distress game among college students.
      reported that AT, as applied to university students in Korea, was effective at reducing stress, which indicated AT could be applicable and effective in patients, adults, and healthy university students. However, the research method used by Song and Kim was a modified version of the traditional AT intervention, except that a tape recorder, rather than autosuggestion, was used to induce subject self relaxation. Thus, the present study differs, as it involved an expansion of AT by using traditional autosuggestion to enhance passive concentration ability.
      Third, the present study differs substantially from previous studies with respect to subject selection.
      • Kanji N.
      • White A.
      • Ernst E.
      Autogenic training to reduce anxiety in nursing students: randomized controlled trial.
      reported that AT induced significant relief on anxiety in second through fourth year nursing students. However, Kanji et al. applied their testing methods to students regardless of their grade, whereas we used stress response measures and applied them to third year nursing students, who were experiencing clinical practice for the first time, and thus, exposed to higher levels of real stress than students in other grades.
      Fourth, the results of this study showed no effect on physiological variables measured by HRV. We found normalized LF was increased and normalized HF decreased with time. In other words, the activity level of the sympathetic nervous system was elevated and the activity level of the parasympathetic nervous system was reduced in the experimental and control groups during the study period.
      • Mitani S.
      • Fujita M.
      • Sakamoto S.
      • Shirakawa T.
      Effect of autogenic training on cardiac nervous activity in high-risk fire service workers for posttraumatic stress disorder.
      investigated the effect of AT on the autonomic nervous system and found the activity level of the sympathetic nervous system was significantly reduced and the activity level of the parasympathetic nervous system was increased in high-risk firefighters.
      • Miu A.C.
      • Heilman R.M.
      • Miclea M.
      Reduced heart rate variability and vagal tone anxiety: trait versus state, and the effect of autogenic training.
      also reported that AT increased HRV and facilitated vagal control of the heart in healthy volunteers under mental stress.
      • Lee J.K.
      The effect of autogenic training on heart rate variability.
      also reported that AT increased resistance to stress by alleviating the sympathetic nervous system and activating the parasympathetic nervous system in normal adults, and showed a significant difference between indicators, that is, mean HRV, standard deviation of the NN interval, and standard deviation of difference between adjacent NN intervals, which were measured by time-domain analysis. However, in this study, LF and HF were measured by frequency-domain analysis and were not found to show any significant difference. Therefore, a more elaborate study is required to check HRV by time-domain and frequency-domain analysis at the same time and to examine their relationship.
      Fifth, this study provides more elaborate information for future research by presenting inconsistencies between physiological and psychological variables.
      • Dishman R.K.
      • Nakamura Y.
      • Garcia M.E.
      • Thompson R.W.
      • Dunn A.L.
      • Blair S.N.
      Heart rate variability, trait anxiety, and perceived stress among physically fit men and women.
      reported an inverse relationship between the normalized HF component of HRV and perceived stress. They found that AT when viewed as a psychological factor, was effective at relieving stress response, whereas when viewed as a physiological factor, it did not affect HRV. This lack of consistency between stress recognition and physical reactions concurs with that found by
      • Chung S.Y.
      • Kim J.W.
      The correlation between HRV and questionnaires before and after oral test.
      , who analyzed relationships between psychological stress and HRV and showed mental and physical responses were not always consistent. Chung and Kim suggested this inconsistency was due to differences in measurement times. During the questionnaire survey subjects were asked to assess their stress responses for a certain period of time, such as 1 month or 1 year, whereas they presented physical state, HRV, at the specific point of measurement time. This result demonstrated that sociopsychological indicators are not always consistent with physiological indicators. Therefore, we suggest more research be conducted to determine the reasons for this inconsistency and to develop objective and valid measurement indicators.
      Sixth, this study suggests the need to manage stresses experienced by nursing students, and provides methods for coping with stress. Previous studies have shown nursing students experience various stresses in clinical practice (
      • Kim J.I.
      • Lee J.S.
      Effects of clinical training on stress, anxiety and changes in autonomic nervous system in nursing students.
      ) that affect self-efficacy, self-respect, autonomous neuro-systems, and clinical competence (
      • Kim H.S.
      A study on relationship between stress of clinical practice and clinical competency in nursing students.
      ,
      • Kim J.I.
      • Lee J.S.
      Effects of clinical training on stress, anxiety and changes in autonomic nervous system in nursing students.
      ,
      • Whang S.J.
      The relationship between clinical stress, self-efficacy, and self-esteem of nursing college students.
      ). However, it is regarded as the students' responsibility to take care of their own stress in nursing school. Therefore, we recommend that more specific, concrete approaches by instructor in the nursing school be taken to address the issue of nursing students' stress. Furthermore, nursing students should be given training guidelines, which cite active stress coping strategies that allow students to adapt to college life, accept stressful situations positively, and manage them in advance. In particular, we recommend that a relaxation program, such as, AT, designed to enable nursing students to manage stresses arising during clinical training, be incorporated into all university nursing training programs.

      Limitations

      The subjects of this study were third-year nursing students attending a four-year program at two universities. One of the limitations in this study is that convenience sampling rather than random sampling was used. The general characteristics of the two study groups, such as, religion, burden of tuition, residence type, admission motives, and satisfaction with educational, were similar, and the groups were well-matched in terms of gender and grade. However, clinical settings, college-related variables, such as examination and academic schedules, and personal situations could not be controlled. Accordingly, it is difficult to generalize our results to all nursing students. Furthermore, careful consideration of study design, such as, the provision of a psychologically and physically comfortable environment is needed for precise HRV measurements, because comfort is likely to affect the autonomic nervous system. We suggest future studies on AT address these limitations to enable the generalization of results.

      Conclusion

      The results of this study are useful and legitimate because they show AT has a positive effect on relief from stress response in nursing students, but no effect on HRV. Thus, because nursing students are expected to cope with stress resulting from their studies and clinical training, stress coping methods should be developed via further research so that student experiences of courses and clinical training are more rewarding. AT is a method that aids the achievement of these goals because it is offers a cost-effective approach that can be easily practiced.

      Conflict of interest

      The authors have no potential conflict of interest to declare.

      Acknowledgments

      We gratefully acknowledge financial support from the Academic Research Fund of Hoseo University in 2012 (2012-0281).

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