Cardio-respiratory response of young adult Indian male subjects to stress: Effects of progressive muscle relaxation
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0975-2870.128971
Background: Stress and anxiety have become an integral part of our lives. Of late, this has resulted in the increase in incidence of hypertension and coronary heart disease. Objectives: To assess the effect of progressive muscle relaxation (PMR) on young adult males and its role in the modulation of cardio-respiratory response on exposure to stress. Materials and Methods: This prospective cross-sectional study was conducted in a tertiary care referral hospital. Undergraduate male students under stress were chosen for the study. Fasting blood samples were drawn to analyze sugar and lipid profile, followed by anthropometric measurements and ECG. In the resting condition, blood pressure, pulse rate, and spirometric parameters; forced vital capacities (FVC), and forced expiratory volume in 1 sec (FEV 1 %) were measured. Then, they were made to exercise with bicycle ergometer and post exercise, the vital parameters were recorded. All subjects were given a training of Jacobson's Progressive Muscular Relaxation and asked to practice this technique for 3 months. All parameters were re-evaluated. Results: Significant decreases in resting heart rate, systolic blood pressure and diastolic blood pressure, total cholesterol, triglyceride, and low density lipoprotein (LDL) cholesterol levels of subjects were seen after PMR training. Exercise-induced rise in heart rate and blood pressure were also significantly less in subjects following PMR training. Conclusion: Progressive muscle relaxation helps in modulation of heart rate, blood pressure, and lipid profile in healthy normal adult male individuals. Keywords: Cardiovascular diseases, progressive muscle relaxation, stress
Stress is defined as a state of threatened homeostasis and it is re-established by complex behavioral and physiologic adaptive responses. It has become an integral part of our daily lives. [1],[2] Stress experiences often lead to various chronic morbid medical conditions such as hypertension and coronary heart disease. [3],[4] Psychological stress either at work or at home raises the risk of myocardial infarction. [5],[6],[7] Stress at work is an important risk factor for the emergence of metabolic syndrome. Autonomic imbalance is also associated with stress. [8],[9] Students are exposed to high levels of stress at an early age. Male students are affected more due to the testosterone which increases the circulating levels of low density lipoprotein cholesterol (LDL-C) and decreases plasma high density lipoprotein cholesterol (HDL-C). [9],[10] Estrogens have a significant plasma cholesterol lowering action and they rapidly produce vasodilatation by increasing the local production of nitric oxide. Estrogen is known to be a vagotonic and sympatholytic hormone. [9],[10] Hormonal factors do cause of variance in Heart Rate Variability among males and females. These actions inhibit atherogenesis and contribute to the low incidence of Acute Myocardial Infarction (AMI) and other complications of atherosclerotic vascular disease in premenopausal females. [11],[12] Hence, young males suffer more from cardiovascular diseases as compared to females of the same age group. Along with available medical therapies, use of cognitive-behavioral intervention is known to be beneficial in improving the quality of life [13] . Progressive muscle relaxation (PMR) technique developed by Edmund Jacobson [1] is a recognized method for reduction of stress and anxiety. Muscle tension accompanies anxiety; one can reduce anxiety by learning how to relax the muscular tension. [2] PMR has gained popularity as an effective tool in various health conditions, ranging from hypertension to epilepsy [1] Dehdari et al. [10] observed the positive effects of PMR on the quality of life in anxious patients after coronary artery bypass graft surgery. Based on these observations, the present study was designed to assess the effect of PMR on young adult males and its role in modulation of cardio-respiratory response on exposure to stress.
This prospective cross-sectional pilot project was conducted in a tertiary care hospital of West Bengal in a time span of 12 months, after receiving approval from the institutional ethics committee and also informed consent of the subjects. Inclusion Criteria Undergraduate male students in the age group of 18-20 years were chosen for the study. Students from different colleges and different courses were included. Exclusion Criteria Subjects suffering from chronic debilitating diseases such as cardiac arrhythmias, hypertension, diabetes, ischemic heart disease, retinopathy, nephropathy, or respiratory diseases, smokers, those with family history of metabolic diseases including diabetes and hypertension, persons receiving any drug that may affect the autonomic reflexes, and those on any daily exercise regime or practicing yoga were excluded. Methods Approval from the institutional ethical committee was taken before conduction of this cross-sectional study. Informed consent was taken from the subjects. Sampling was performed using multistage and random cluster method. [11] The first stage of sampling included a simple random sample to select five colleges in the region. In the second stage of sampling, 100 students were selected from each of these colleges, who were then administered questionnaires. [13] On the first appointment, particulars of the subject, personal history, family history, history of past illness, treatment history, and dietary history of the subjects were carefully recorded. Stress level in the subjects was assessed according to the Holmes - Rahe stress scale. [14] Five hundred male subjects were asked to tally a list of 43 life events based on a relative score. Finally, 122 males with scores of 150 and above were chosen for the study, as they had a moderate to high risk of illness according to the stress scale of Holmes - Rahe. [14] Informed consent was obtained from the subjects. After clinical examinations were conducted and pre-test instructions were given to avoid consumption of any drugs that may alter the autonomic function 48 h prior to the test, the subjects were advised to have a good restful sleep. The subjects were advised to have light dinner within 8 p.m. and go to bed early, and avoid stressful situations during the day before the tests were conducted. Relaxing bedtime routine, such as soaking in a hot bath or hot tub and then reading a book or listening to soothing music, was advised. They were asked to avoid caffeine (e.g. coffee, tea, and soft drinks, chocolate), nicotine (e.g. cigarettes, tobacco products), and alcohol close to bedtime. On the day of the test, no cigarette, nicotine, coffee, or drugs was permitted. Fasting blood samples were drawn to exclude diabetes. Baseline anthropometric measurements, ECG, and lipid profile analysis were carried out. Body Mass Index (BMI) was recorded for each subject. Among the 122 subjects, 3 had pathological waveforms in ECG, and in 1 subject, fasting sugar was more than the normal level. So, they were excluded from the study. Ultimately, 116 were included in the study. The tests were performed at controlled room temperature in the morning between 10 a.m. and 11 a.m. Subjects had light breakfast at least 3 h prior to exercise testing and at least 24 h of abstinence from any form of alcohol, tobacco, tea, and coffee. It was ensured that they had not undergone any strenuous work or exercises 3 h prior to the tests. [14] In the resting condition, blood pressure, pulse rate, and spirometric (Helios Spirometer 401) parameters, forced vital capacity (FVC), and forced expiratory volume in 1 sec (FEV 1 %) were measured. Then, they were made to exercise with bicycle ergometer. A mechanically operated bicycle ergometer with brakes was used. The exercise involved pedaling at a speed of 60 times/min, with breaking resistance of 1.75 kg, for 3 min (work done 450 kpm/min). After cessation of exercise, the previous parameters were again recorded. All subjects were given a training of PMR. Training involved tensing the specific muscle groups for 7-10 sec, followed by releasing them (relaxing) for 15-20 sec as per Jacobson's [1] protocol [Table 1]. They were asked to practice this technique at home for 20 min every day for 3 months and come for follow-up. Subjects were followed up at regular intervals during this period. Twelve subjects did not turn up for follow-up. Three subjects were very irregular in performing relaxation exercises, so they were excluded. Therefore, the final sample consisted of 101 subjects.
After 3 months, the lipid profile and vital parameters were rechecked and subjects were asked to repeat the same exercise. After exercise, the vitals were recorded in a similar fashion. Data Analysis Data obtained was analyzed using SPSS software version 16(IBM). t-Test was used to analyze the data. The data were considered significant and highly significant if the analyzed probability values (P values) were <0.05* and <0.01**, respectively.
Five hundred male subjects were asked to tally a list of 43 life events. One hundred and twenty-two males with scores >150 were chosen for the study. Among the 122 subjects, 3 had pathological waveforms in ECG, and in 1 subject, fasting sugar was more than the normal level. So, they were excluded from the study. Ultimately, 116 were included in the study. Twelve subjects did not turn up for follow-up. Three subjects were very irregular in performing relaxation exercises, so they were excluded. Therefore, the final study sample consisted of 101 subjects. Mean age of the subjects was 19.02 ± 1.5 years, BMI was 20.58 ± 1.42 kg/m 2 , and fasting blood sugar was 83.01 ± 2.8 mg/dl. We found statistically significant exercise-induced rise in heart rate (HR), systolic blood pressure (SBP), and decrease in FVC and FEV 1 [Table 2] and [Table 3]. Significant decrease in resting HR (pre 80.51 beats/min vs. post 75.21 beats/min), SBP (pre 127.52 mm of Hg vs. post 120.45 mm of Hg), and diastolic blood pressure (DBP; pre 78.11 mm of Hg vs. post 75.25 mm of Hg) was seen after PMR training in the subjects [Table 4]. Exercise-induced increases in HR (119.97 beats/min vs. 114.23 beats/min), SBP (147.68 mm of Hg vs. 140.43 mm of Hg), and DBP (79.25 mm of Hg vs. 76.48 mm of Hg) were also significantly less in subjects following PMR training [Table 5].
There was significant decrease in total cholesterol, triglyceride, and LDL-C levels in subjects after practicing PMR for 3 months [Table 6]. No significant effect of PMR training was found on FVC and FEV 1 .
In India, every year, approximately 1.5 million deaths occur due to cardiovascular diseases. Negative emotions are strongly related to the development of heart diseases. A reduction in positive mood and increase in worry can reduce blood supply to the heart within 15 min, which may lead to "silent transient myocardial ischemia." [6],[7],[8] The stress response becomes maladaptive in individuals under chronic stress exposure. This fosters low-grade systemic inflammation and coagulation activity. Chronic stress, personality characteristics, and emotional states are associated with essential hypertension. [15] Owing to the associated morbidity and mortality, and the cost to individual and society, hypertension is an important public health challenge. [15] Therefore, stress reduction strategies for individuals and communities may be beneficial in reducing cardiovascular disease and its deleterious effects. [11] PMR is thought to be more effective in altering cardiovascular parameters as compared to respiratory ones. [1],[9] In the present study, significant decreases in resting HR and SBP and DBP of subjects were observed after PMR training, which is similar to the observations made by Khanna et al. [1] in 2007. Although increase in all these cardiovascular parameters was noticed following exercise, it was significantly less in subjects after PMR training. This decreased cardiovascular response to stress may be a result of complex interplay of physiological and psychological mechanisms to reduce the anxiety in subjects practicing PMR, [2] as PMR training is known to increase parasympathetic activity, reduce muscle tension; improve concentration, and leads to a sense of well-being. [2] Matousek et al. [9] observed that PMR not only improves the clinical parameters but also decreases cortisol levels and results in decrease of total cholesterol, triglyceride, and LDL-C levels. In the present series also, we found significant decrease in total cholesterol, triglyceride, and LDL-C levels in subjects after practicing PMR. In 2010, Shahnam et al. [11] demonstrated higher levels of total cholesterol and LDL-C and lower levels of HDL-C among stressed individuals. Hence, stress produces significant cardiovascular hazards by altering biochemical parameters. Thus, practicing PMR may alter the lipid profile and help in prevention of cardiovascular diseases. PMR did not alter respiratory parameters in this series, which supports the previous observations made by Khanna et al. [1] Using an open-ended question along with Holme's and Rahe's Social Readjustment Rating Schedule, Singh et al., on a sample of 200 adult subjects, constructed a suitable scale of stressful life events experienced by the Indian population, the Presumptive Stressful Life Events Scale (PSLES). Analysis of various demographic variables for this population revealed no differences on this scale for age, marital state, education, and occupation. However, marked sex differences in the perceived stressfulness were observed for three of the items (related to family matter relevant for female subjects). The PSLES is simple to administer to literate and illiterate subjects. We excluded females from our study and all our subjects were literate. So, we used Holmes - Rahe stress scale in our study. [14],[15],[16],[17],[18] Limitations of the Study Some of the physiological mediators that work with cortisol, viz. salivary immunoglobulin A, salivary amylase, dehydroepiandrosterone, catecholamine, cytokines, and the other glucocorticoids, whose measurement may contribute to a more comprehensive understanding of the body's response to stress, were not included in the study. They could have thrown further light. The stress scores have not been given on the basis of the PSLES and females were excluded. This may be a limitation of our study.
PMR helps in modulation of HR, blood pressure, and lipid profile in healthy normal adult males, as observed in this study. Following exercise, it reduces increase in HR and blood pressure. These relaxation techniques will benefit the population at large if adopted early to improve the quality of life in a stressful environment.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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