The effects of muscle relaxation on blood pressure of essential hypertensives

Muscle relaxation and noncontinuous biofeedback were investigated as potential nonpharmaceutical treatments for essential hypertension. The two procedures were compared to a waiting list control group. Predictions were made regarding the overall treatment effect, sessions within treatment effect, and periods within session effect. The results of this experiment reveal that biofeedback significantly lowers diastolic blood pressure between premeasures and postmeasures. It was also shown that muscle relaxation has a significant effect upon lowering diastolic and systolic blood pressures between premeasures and postmeasures and has a significant effect upon lowering diastolic and systolic blood pressures as subjects progress from the first period of a treatment session to the last period of a treatment session.     

Voluntary Blood Pressure Control: Operant Conditioning by a Continuous Blood Pressure Feedback Technique

Abstract

The present study evaluated a single session operant conditioning of blood pressure in borderline hypertensives. A double blind randomized two period (each lasting for 20 minutes) cross over study consisting of a treatment (operant conditioning of mean arterial blood pressure) and a control condition (heart rate) was performed. Sequence of treatments was randomly assigned. Fourteen borderline hypertensive subjects participated and were trained to decrease their continuously measured blood pressure (Finapres) and heart rate. Subjects receiving blood pressure feedback during the first session showed a significant (4.3 mmHg) decrease in diastolic blood pressure. In contrast, subjects receiving blood pressure training during the second session showed a non-significant increase in diastolic blood pressure. Treatment consisting of more sessions is a promising adjunct to antihypertensive regimens.     

The influence of gender, hypertension risk, and aerobic fitness on cardiovascular responses to laboratory-induced stress

The study sought to evaluate the influence of gender, hypertension risk, and aerobic fitness on cardiovascular responses to laboratory-induced stress. Sixty nonsymptomatic subjects (30 males, 30 females) participated in the experiment. Half of the subjects had at least one biological parent with hypertension, while half had no parental history of hypertension and served as comparison subjects. Subjects completed a laboratory procedure measuring cardiovascular responses (i.e., pulse rate and blood pressure) while performing stressful laboratory tasks (i.e., the Stroop Color Naming Test and a sham IQ test). Aerobic fitness (i.e., VO_2max using the Bruce protocol) was also determined using a submaximal treadmill test in the laboratory. Results suggest that males with a family history of hypertension were more stress responsive based on systolic blood pressure, while females were more stress-responsive according to pulse rate activity. Fitness levels were significantly associated with diastolic blood pressure throughout the stress and recovery periods but were unrelated to pulse rate and systolic blood pressure.     

Multiple sessions of systolic blood pressure biofeedback: Its effects on ability to control systolic pressure during training,after training,and its effects on pulse rate

Seventy-one normotensive subjects participated in four training sessions in which they were either (a) instructed to increase their blood pressure, (b) instructed to decrease their blood pressure, or (c) not instructed to change their blood pressure. The subjects either (a) were provided with biofeedback concerning systolic blood pressure or (b) were not provided with biofeedback concerning systolic blood pressure. After the last training session, subjects participated in a transfer session in which they were again instructed concerning changes in pressure but were not provided with biofeedback. Analyses conducted on data from the training and transfer sessions indicated that subjects who were instructed to increase pressure and given biofeedback to aid them showed higher pressure than subjects in other conditions and that there were no differences among those other conditions; that is, biofeedback was effective for teaching subjects to increase pressure but was not effective for teaching subjects to decrease pressure. Additional training sessions did not add to the effect achieved in the first training session. During training sessions, subjects who were instructed to increase pressure showed higher heart rates than subjects in other conditions. The results raise questions concerning the interpretation of earlier experiments that did not include no-treatment, instructions-only, and attention control conditions.     

The effect of specific hypnotic suggestions on blood pressure in normotensive subjects

Twenty normotensive subjects participated on a voluntary basis in an experiment designed to study the effects of specific suggestions on blood pressure (BP). After an induction procedure, the experimental group received suggestions presumed to be relatively nonactivating, although capable of lowering or raising BP. A control group was used to record the BP changes over time. All subjects met for one session. Eight subjects from the experimental group met for a second session. Both adaptation and induction resulted in significant BP decreases. A specific suggestion to increase BP gave a significant result when compared to the induction point. There was no significant change from induction to the BP decrease suggestion. Both systolic and diastolic BP behaved in the same way. A second experimental session resulted in no significant change compared with the first session. Also, no significant difference was found in suggestibility scores from the first to the second session. The results are in line with previously published studies.     

Task difficulty, cardiovascular response, and the magnitude of goal valence

Sixty-four young women expected to perform an easy, moderately difficult, or extremely difficult memory task with the opportunity to earn a small incentive for good performance. Cardiovascular (heart rate, systolic and diastolic blood pressure) and subjective measures were taken immediately prior to task performance. Both systolic blood pressure (SBP) responses and ratings of goal attractiveness were nonmonotonically related to expected task difficulty, with the most pronounced SBP elevations and highest goal attractiveness in the moderately difficult task condition. Product-moment correlations among cardiovascular response measures revealed a strong positive association between systolic and diastolic pressure (but not heart rate) change in the easy condition, positive relationships among all measures in the moderately difficult condition, and no significant correlations in the extremely difficult condition. Subjective measures of arousal were not affected by the task difficulty manipulation. Principal findings are discussed in terms of a theoretical model proposed by Brehm (1979) that states that motivation varies as a nonmonotonic function of the difficulty of goal attainment. Intercorrelations among cardiovascular response variables are considered in terms of their possible indication of the mechanisms underlying blood pressure changes associated with variations in motivation.     

Effect of Relaxation Therapy in Reducing Blood Pressure of Essential Hypertension Patients

The study investigated the effect of relaxation therapy on arterial blood pressure of Patients with essential hypertension. Ten known essential hypertension patients (males = 3; females = 7, age range 41–70, mean age 57.2 years, SD = 9.93 years) were sampled randomly from Medical outpatient department of the State owned University teaching Hospital in Ebonyi State South East, Nigeria. These Participants were exposed to 30 minutes relaxation therapy and their blood pressures were taken before and after the treatment. Using matched t test to compare baseline and post treatment scores, result showed that relaxation therapy progressively decreased both diastolic and systolic blood pressure readings of the Participants. The study concluded that Relaxation therapy can transiently lower the systolic and diastolic blood pressure.     

Task-related arousal of type A and type B persons: level of challenge and response specificity

To determine whether different levels of challenge had differential effects on the arousal levels of Type A and Type B persons, 30 Type A and 30 Type B male subjects worked on an intelligence test task (digits backwards recall) that was easy, moderately difficult, or extremely difficult. Arousal was measured in terms of systolic blood pressure, diastolic blood pressure, pulse rate, pulse volume, skin resistance, and subjective arousal. Results indicated that while working on the extremely difficult task, the Type A subjects evidenced reliably higher systolic blood pressure than did the Type B subjects (p = 0.1; difference = 7.52 mm of Hg) and that there were not reliable differences between the subjects in systolic blood pressure at other levels of challenge or on other measures of arousal.     

Hypertension risk and caffeine's effect on cardiovascular activity during mental stress in young men

Examined the cardiovascular effects of caffeine plus behavioral stress in men low versus high in risk of essential hypertension. Caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) or placebo was given on alternate days to 19 low-risk men (negative for parental hypertension and low-normal resting blood pressure, BP) and 20 high-risk men (positive history, high-normal BP). Forty minutes later, each worked for 15 min on a demanding psychomotor task during which BP, cardiac output, and vascular resistance were determined. During rest, caffeine raised vascular resistance in both groups. During the task, it supra-additively increased the systolic BP response by enhancing the rise in cardiac output, producing equivalent BP rises in both groups. Due to the higher resting pressures of the high-risk men, caffeine plus the task resulted in 50% of these having transient BP of 140/90 mg Hg or greater. Caffeine in combination with mental stress may produce undesirable BP in those at risk for hypertension.     

THE EFFECTS OF FEEDBACK ON BLOOD PRESSURE DISCRIMINATION

Discrimination of blood pressure in the natural environment as a function of feedback was assessed. Seventeen normotensives screened for blood pressure lability were randomly assigned to two groups. These subjects were then asked to estimate their systolic and diastolic blood pressure values two times per day over a 4-week period. Feedback for accuracy of blood pressure discriminations was implemented across the two groups in a multiple baseline fashion, using a feedback withdrawal condition in Group I to assess maintenance effects over time. Results showed improvement in discrimination accuracy for subjects in both groups when feedback was used, and no decrement in performance over a 2-week period after feedback was removed for subjects in Group I. Discrimination of systolic pressures improved at a slightly faster rate than discrimination of diastolic pressures.     

The type a behavior pattern,sex differences,and cardiovascular response to and recovery from stress

Sixty-one subjects performed a Stroop Color-Word Interference task, a mental arithmetic task (serial subtraction of 7s), and a shock avoidance task (repeating digits backward while expecting to be shocked for mistakes). Systolic and diastolic blood pressure and pulse rate were recorded while subjects anticipated, undertook, and recovered from the shock avoidance task, and undertook and recovered from the Stroop and mental arithmetic tasks. The results revealed that, compared to Type B subjects, Type A subjects manifested higher diastolic blood pressure during the Stroop and shock avoidance tasks and higher pulse rate following the mental arithmetic and shock avoidance tasks. No significant interactions were found between sex and A/B Type. The results are congruent with the notion that greater sympathetic nervous system activity among Type A individuals, both men and women, contributes to greater coronary atherosclerosis and heart disease in this group.     

EVALUATION OF BIOFEEDBACK IN THE TREATMENT OF BORDERLINE ESSENTIAL HYPERTENSION1

Direct biofeedback of blood pressure was compared with frontal EMG biofeedback and with self-instructed relaxation for the treatment of essential hypertension in a controlled group outcome study. Patients were followed up for four months after the end of treatment. Generalization of treatment effects was assessed through pre- and posttreatment measurements of blood pressure under clinical conditions in a physician's office. There were no significant reductions in diastolic blood pressure. The systolic blood pressure (SBP) of the patients receiving blood pressure biofeedback decreased 8.1 mm mercury (p = 0.07) and the SBP of the patients in the relaxation condition decreased 9.5 mm mercury (p = 0.05). In the generalization measures, there were significant reductions in SBP for the relaxation group. The results are discussed in terms of the general lack of replicability within the area of biofeedback treatment of hypertension.     

Blood pressure reactivity to active and passive behavioral conditions in hypertensives and normotensives

Blood pressure reactivity and passive behavioral tasks was studied in patients with mild essential hypertension and normotensive controls. The passive condition included 10 presentations of a 6 sec, 78 dB, 1000 Hz tone without any response requirements. In the active condition subjects were given an additional 10 tone presentations and asked to press a push-button at tone termination. The absolute and percent increase in systolic blood pressure from rest was greater in hypertensives than normotensives in response to the active condition but similar to the passive condition. It is concluded that patients with hypertension compared to normotensive controls show exaggerated blood pressure reactivity to tasks involving active but not passive coping efforts. Since the tasks used to induce active and passive coping in the present study were identical apart from coping requirements, the notion that the activity dimension in and of itself modulates reactivity differences between patients and controls is supported.     

Interactive but not direct effects of perceived racism and trait anger predict resting systolic and diastolic blood pressure in black adolescents.

This correlation study explicated the association of perceived racism and trait anger to resting blood pressure in a high school sample of 234 Blacks. Perceived racism and trait anger were assessed via self-report, and resting blood pressure was measured with a noninvasive blood pressure monitor. Hierarchical regression analyses indicated that perceived racism and trait anger were not independent predictors of systolic or diastolic blood pressure. However, these analyses revealed that the interactive effects of perceived racism and trait anger were predictive of systolic and diastolic blood pressure. Although perceived racism was not significantly related to blood pressure among those who were high in trait anger, perceived racism was inversely associated with blood pressure among those who were low in trait anger. The findings may have important longer term implications for future research examining the contribution of psychosocial factors to cardiac and vascular functioning in Blacks.     

ACQUISITION,DISCRIMINATIVE STIMULUS CONTROL,AND RETENTION OF INCREASES/DECREASES IN BLOOD PRESSURE OF NORMOTENSIVE HUMAN SUBJECTS1

The aims of this study of 24 normotensive subjects were: to compare a free-operant with a discrete-trials training format; to determine the most effective training procedure by comparing instrumental conditioning with instructional set and a control; to see if both increases and decreases in blood pressure could be brought under discriminative control, and to examine the maintenance of acquired self-control of blood pressure. A 2 × 3 design was employed in which two trial formats (free operant and discrete trials) were factorially compared with three training conditions (instrumental conditioning, instructional set, and control). Instrumental conditioning was found superior to both the instructional set and control conditions in producing increases and decreases in mean diastolic blood pressure. The free-operant format led to a greater degree of learned BP control in that subjects were able to increase and decrease their blood pressure by 10% to 15% of basal value and to maintain the blood-pressure operant after contingent auditory feedback/reinforcement was removed. Training was discontinued when subjects in the other five groups failed to reach criterion after 10 consecutive acquisition sessions.     

Cardiovascular reactivity to psychological stress in aerobically trained versus untrained mild hypertensives and normotensives

Cardiovascular reactivity to video game and mental arithmetic stressors was compared among three groups of men: aerobically trained mild hypertensives, untrained mild hypertensives, and a comparison group of untrained normotensives. Relative to the untrained hypertensives, the trained hypertensives reacted to the video game with marginally smaller systolic blood pressure and diastolic blood pressure, but there were no significant differences between these groups in reactivity during the mental arithmetic task. Comparisons between each hypertensive group and the normotensive group showed that blood pressure (BP) reactivity of normotensives during the video game was generally similar to that of trained hypertensives but smaller than that of untrained hypertensives. These results indicate that aerobic training, which has been found to reduce resting BP in mild hypertensives, may also exert a favorable impact in reducing cardiovascular reactivity of hypertensives during some stressful situations.     

Hemodynamic characteristics of young men at risk for hypertension at rest and during laboratory stressors.

Examined hemodynamic activity--at rest, during mental arithmetic, and during hand cold pressor--in young men varying in risk for hypertension. Classification into low-risk (n = 72), moderate-risk (n = 20), and high-risk (n = 13) groups was based on resting systolic blood pressure (SBP) and parental history of essential hypertension (PH). Dependent variables were SBP, diastolic BP (DBP), heart rate, and rate-pressure product (RPP). Progressively greater hemodynamic activity was seen across risk groups at rest and during the tasks. Risk groups differed significantly in SBP, DBP, and RPP at baseline (ps less than .003) and in size of response to mental arithmetic (ps less than .05) but not to cold pressor. These relationships were either absent or weaker when using either risk factor alone to form risk groups. These findings suggest that hemodynamic reactivity to mental stress is predicted better by a combination of resting SBP and PH than by either risk factor alone and that physiological reactivity may be an important accompaniment of increased risk for hypertension.     

Does anxiety or cardiovascular reactivity have a causal role in hypertension?

Anxiety, stress, and cardiovascular reactivity (CVR) are variously believed to play a role in sustained hypertension. Although acute anxiety or stress elicits acute pressor responses, there is little support for their significant role in sustained hypertension. Anxiety correlates poorly with CVR, and blood pressure levels and anxiolytics do not sustain blood pressure lowering in subjects with hypertension-associated anxiety. Chronic anxiety disorders tend to be characterized by relatively low blood pressure and prevalence of sustained hypertension. Blood Pressure Regulation in hypertension is normal, and normo- and hypertensives have similar ambulatory blood pressure variability. Laboratory CVR fails to predict variability in natural environments, hyperreactors do not exhibit increased variability in natural environments, and the increased variability and ambulatory reactivity that is "accounted for" by laboratory responses is small. These findings do not support the belief that hypertension is related to a summation of heightened pressor responses over time. Antihypertensives normalize elevated blood pressures but do not alter CVR in the laboratory or variability in natural environments, probably because of a dual central regulation of resting and reactive blood pressures. Psychological stress responses result from selective neuronal activation rather than from generalized sympathetic neural responses or dysregulation. Differences in blood pressure responses during various emotions are only quantitative, with no specificity of sympathoadrenal or emotional responses to stressors. It may be time to regard reactive cardiovascular responses as physiological, rather than as psychological, and to require much stronger evidence to confirm causal roles of anxiety, stress, and reactivity in sustained hypertension.     

Ambulatory and laboratory blood pressure in individuals with negative and positive family history of hypertension.

Undertook 24-hr ambulatory blood pressure (BP) monitoring in men and women with and without family history of essential hypertension. Cardiovascular functions were also recorded in the laboratory during mental arithmetic, image star tracing, isometric exercise, and the cold pressor test. Ambulatory daytime, but not nighttime, systolic and diastolic BP as well as heart rate (HR) level and variability was higher in those with than without family history. During sleep, HR level and variability were higher among those with family history; at rest in the laboratory, however, all cardiovascular functions were similar in both groups. The strongest laboratory-based predictor of daytime BP was stress-induced BP levels. BP reactivity also significantly predicted daytime BP but with less accuracy. The best predictor of BP and HR at sleep was resting cardiovascular functions. Thus, ambulatory BP recordings add information to resting and stress-induced levels in identifying cardiovascular risk reactions.     

Cardiovascular Responses to Threat: Effects of the Difficulty and Availability of a Cognitive Avoidant Task

Measures of heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were taken during an interval immediately preceding a period in which male subjects were to perform an easy or difficult memory task to avoid a noxious noise, or simply wait to receive the noise. As predicted, anticipatory elevations in SBP and HR were relatively higher in the difficult avoidance condition than in the easy and impossible avoidance conditions. In contrast, anticipatory DBP change-scores decreased linearly from easy to difficult to impossible avoidance conditions. Results are discussed in terms of a recent motivational theory suggesting that energy mobilization in the face of threat should be a function of what can, will, and must be done to cope.