Relaxation and subjective estimates of muscle tension: Implications for a central efferent theory of muscle control

The relationship of “awareness of muscle tension” to depth of relaxation was explored. In one experiment, accuracy of forearm flexor control was assessed using the psychophysical method of magnitude production, and depth of flexor relaxation was measured using the integrated EMG before and after EMG biofeedback training. No consistent relationship between motor-control accuracy and depth of relaxation was found. A second, similar experiment with frontalis showed increased accuracy of frontalis control with deeper relaxation. Accuracy of passive, verbal judgments of spontaneous frontalis tension fluctuation exhibited no clear relationship with depth of relaxation. It was concluded that forearm flexor and frontalis may be under the control of distinct mechanisms, and that afferent information probably contributes to the control of neither muscle. Three structural theories of the control mechanisms were considered, and one depending on the central monitoring of efferent outflow(rather than afferent inflow) seemed most compatible with the frontalis data. Both flexor and frontalis data could be accounted for by a two-phase scheme combining central outflow monitoring with the monitoring of mental contents for arousal value at very low muscle tension levels.     

Awareness during electromyographic biofeedback: Of signal or process?

During relaxation training, awareness of trial-to-trial changes in frontalis-muscle tension levels was assessed with and without auditory electromyographic(EMG) biofeedback. Immediately after each 128-sec training trial, the subject was required to guess whether muscle tension indexed by EMG activity increased(“Up”) or decreased(“Down”) relative to the immediately preceding trial. The probability of correct guessing, P(c), improved as the absolute difference in EMG increased between trials only when biofeedback was presented. For subjects not receiving biofeedback, P(c) remained low even when the absolute difference between trials was large. Subjects in each condition employed a strategy to guess “Down” more often consistent with the expectation that they were being trained to relax. The “Down” set strategy was shown to be separable from the informational basis of P(c) provided by biofeedback. This procedure can be employed to evaluate central assumptions of biofeedback relating to posttraining awareness of changes in muscle tension and the relationship between awareness and control of muscle tension.     

EMG-biofeedback reduction of tension headache

The biofeedback literature affirms the therapeutic efficacy of EMG-biofeedback-assisted relaxation for the treatment of tension headache. However, this form of therapy has failed to focus on the role of cognitive variables in the control and perception of tension headache. The present case study provides a prototype treatment combining cognitive behavior-modification procedures with EMG-biofeedback training to treat a subject with chronic tension headache. Phase I, baseline, involved collecting mean EMG and daily headache activity, emphasizing specification of environmental stressors. Phase II, cognitive skills-training, focused on:(1) identifying negative self-statements(cognitions) related to stressors, and(2) training the subject to replace negative self-statements with coping self-instructions. This treatment resulted in a 33% headache reduction over baseline, with no concomitant changes in frontalis EMG. Phase III, EMG-biofeedback training, resulted in a 38% reduction in mean EMG level and a 66% reduction in mean headache activity when compared to baseline. The results suggest the importance of attending to cognitive factors in the treatment of tension headache.This paper was presented at the 6th annual meeting of the Biofeedback Research Society, Monterey, California, 1975.     

Electromyographic biofeedback for relief of tension in the facial and throat muscles of a woodwind musician

Electromyographic(EMG) biofeedback, for the relaxation of specific throat and facial muscles, was given to a woodwind musician. The patient had a nineteen-year history of tics and high levels of tension in his throat and facial muscles. Eventually these problems progressed to a point that interfered with his ability to perform as a professional woodwind musician. Following detoxification from alcohol and Dexamyl, and after a period of psychotherapy, EMG biofeedback relaxation training was started for the muscles specifically showing chronically high tension levels. The EMG training consisted of four phases designed to help the patient progressively lower tension and generalize these newly learned techniques to his professional life. He had a total of twenty treatments of approximately 45 minutes each. This procedure resulted in dramatic reductions in tension levels of the specific throat and facial muscles along with increased proficiency as a muscician and in psychological functioning.     

Incentives to enhance the effects of electromyographic Feedback Training in stroke patients

The use of monetary incentives to enhance the effects of electromyographic(EMG) feedback training was studied in five stabilized stroke patients with hemiplegia. The study was divided into Baseline, EMG Feedback Training, Feedback Training Plus Incentives, and Follow-Up treatment conditions. Integrated EMG activity was recorded simultaneously from the anterior tibialis and medial gastrocnemius muscles during relaxation and dorsiflexion of the affected foot. Patients were instructed to try to increase anterior tibialis EMG activity while decreasing EMG activity in the medial gastrocnemius. Range of motion was measured both prior to and immediately following the Baseline and Feedback Training conditions. Results suggested that(a) EMG feedback training produced greater EMG control and range of motion than did unassisted practice, and(b) the addition of monetary incentives may enhance the effects of feedback training, possibly through its effect on patient motivation.     

The relative effectiveness of three techniques to induce the trophotropic response

The purpose of this study was to examine the relative effectiveness of electromyographic biofeedback training(EMG BFT), remeditation, and progressive muscle relaxation(PMR) in eliciting a relaxation or trophotropic response as measured by frontalis muscle tension, heart rate, electrodermal response, respiration rate, and skin temperature. Fifty-four college students were randomly assigned to one of five groups:(1) control,(2) placebo control,(3) EMG BFT,(4) meditation,(5) PMR. After baseline measures were obtained subjects were trained in 10 30-minute training sessions and posttested. Comparisons by ANOVAs indicated there was a significant decrease in muscle tension in the EMG BFT and meditation groups and significant decreases in respiration rate in the meditation and PMR groups. No other changes were attributed to treatment.     

Change Mechanisms Associated with Combined Relaxation/EMG Biofeedback Training for Chronic Tension Headache

Therapeutic mechanisms hypothesized to underlie improvements in tension headache activity achieved with combined relaxation and eleclromyographic (EMG) biofeedback therapy were examined. These therapeutic mechanisms included (1) changes in EMG activity in frontal and trapezii muscles, (2) changes in central pain modulation as indexed by the duration of the second exteroceptive silent period (ES2), and (3) changes in headache locus of control and self-efficacy. Forty-four young adults with chronic tension-type headaches were assigned either to six sessions of relaxation and EMG biofeedback training (N = 30) or to an assessment only control group (N = 14) that required three assessment sessions. Measures of self-efficacy and locus of control were collected at pre- and posttreatment, and ES2 was evaluated at the beginning and end of the first, third, and lost session. EMG was monitored before, during, and following training trials. Relaxation/EMG biofeedback training effectively reduced headache activity: 51.7% of subjects who received relaxation/biofeedback therapy recorded at least a 50% reduction in headache activity following treatment, while controls failed to improve on any measure. Improvements in headache activity in treated subjects were correlated with increases in self-efficacy induced by biofeedback training but not with changes in EMG activity or in ES2 durations. These results provide additional support for the hypothesis that cognitive changes underlie the effectiveness of relaxation and biofeedback therapies, at least in young adult tension-type headache sufferers.     

Biofeedback-based stress management training with a population of business managers

A biofeedback-based stress management training program was experimentally evaluated using populations of middle-level managers from a large corporation. The training program, once-weekly 1-hour sessions for 6 weeks, combined frontal and other site EMG biofeedback, progressive relaxation and breathing exercises, cognitive stress management, and generalization techniques. Control groups participated in either the assessment procedures only or the assessment procedures and six once-weekly discussions of stress and the job on both an individual(two sessions) and group(four sessions) basis. Significant effects were found in self-report measures, state and trait anxiety, experience of stress; in physiological measures, basal frontal EMG and frontal EMG during recovery from stress, and finger temperature; and in ratings of overall job performance. However, no consistent advantage for the training group or either control group was found. Several possible explanations for the failure of the biofeedback-based stress management training condition to achieve a consistent advantage over the control conditions are presented.     

The effects of frontal EMG biofeedback and progressive relaxation upon hyperactivity and its behavioral concomitants

Hyperactive children(N=15) and nonhyperactive children(N=15) were compared. Hyperactive children were found to possess significantly higher(p < .002) muscular tension levels and, in addition, presented more behavioral problems and had lower test scores. Both electromyographic(EMG) biofeedback and progressive relaxation exercises were successful in the significant reduction of muscular tension, hyperactivity, distractability, irritability, impulsivity, explosiveness, aggressivity, and emotionality in hyperactive children. The greatest improvement was seen in the area of emotionality—aggression(irritability, explosiveness, impulsivity, low frustration tolerance, aggression). No differences were seen in the EMG improvement of drug and nondrug hyperactive children; both made progress under these self-control techniques. However, nondrug children made greater improvements in the behavioral area. Both EMG biofeedback and progressive relaxation resulted in improvements on the test scores of hyperactive subjects(Bender-Gestalt, Visual Sequential Memory, Digit Span, Coding). The therapy would appear to be improved by the inclusion of mental relaxation, concentration, meditation, and mind-blanking exercises for mental control.     

Biofeedback applications to migraine and tension headaches: A double-blinded outcome study

The efficacy of progressive relaxation, fingertip temperature training, and EMG training of the frontalis muscles was tested against chronic migraine and tension headaches in a double-blinded 3×2 design. All 56 subjects reported being conditioned in the course of the nine 1/2-hour training sessions. Detailed records of perceived severity and duration of the headaches were maintained by the subjects before the study and for at least 3 months after the training period. While even a conservativeF revealed a diminution of perceived severity, of hours/month of headache, and of an index conceived by Budzynski, Stoyva, Adler, and Mullaney (1973), across time, at beyond the .05 level of significance, no specific treatment emerged as clearly most effective for either type of headache. Over time, however, progressive relaxation was not as good as the other procedures in reducing the number of hours/month of headache.     

Frontal EMG-biofeedback training of athetoid cerebral palsy patients

Six athetoid cerebral palsy patients participated in the following: speech and motor prebiofeedback training evaluation; frontal EMG biofeedback training, 6 wk; speech and motor postbiofeedback training evaluation, Frontal pretraining levels for the subjects averaged 28.9 µV p-p. Subjects' feedback consisted of an auditory signal(clicks) varying proportionately with frontal EMG activity. A visual meter display of the integrated EMG was also provided. Self-regulation of frontal EMG was evident for all subjects within session 1. Throughout all sessions, EMG levels of 2–4 µV were often attained. Trend analysis of EMG acquisition curves showed significant reduction in frontal tension across sessions for all but one subject. Frontal posttraining levels averaged 13.0 µV p-p. Parents or subjects, or both, reported subtle improvements in various speech and motor functions, a finding confirmed by objective postbiofeedback training evaluation. Only the 2 most severely impaired subjects, JA and DS, failed to improve significantly on the speech measures. All subjects improved significantly on those measures that tapped fine and gross motor skills. Collectively, these results indicate that EMG biofeedback training shows promise as an additional treatment modality in the habilitation of cerebral palsy patients.     

An educational format for teaching stress management to groups with a wide range of stress symptoms

In view of the pervasiveness of stress reactions in contemporary society, together with the limited availability of effective coping techniques, the authors attempted to develop a stress management program that combined education on the nature of stress disorders with instruction on several practical procedures useful in coping with stress. Our study used a general population drawn from a small rural university community. There were 38 subjects, 17 male and 21 female, in the final statistical analyses. One independent variable was a lecture-discussion format to present cognitive and relaxation skills. A second independent variable was biofeedback training to decrease frontal EMG activity. The subjects were divided into five treatment groups that consisted of one or some combination of these two treatment conditions. Dependent variables were the two scales—A-State and A-Trait—of Spielberger's STAI(Spielberger, Gorsuch, & Lushene, 1970) and an adaptive application of Kerle and Bialek's(1958) Subjective Stress Scale(SSS). The SSS served as an instrument to keep subjects aware of their physical and psychological responses to stress as well as providing a pre/post measure of reactions to stress as they experienced it. Results indicated that the lecture-discussion format was effective in reducing the subjects' level of stress as measured by the State-Trait Anxiety Inventory and the Subjective Stress Scale. There was no evidence that frontal EMG feedback relaxation training contributed to the reduction of stress.     

The effectiveness of EMG biofeedback training in low back pain

Eighteen patients with chronic low back pain(lbp) of muscle tension origin were given an EMG biofeedback training. Compared to seven controls they showed a significant decrease during training in muscle tension and subsequently in pain. However, at follow-up EMG levels dropped to the initial(high) level. Pain scores of patients with high pain decrements during training showed further improvement during follow-up, which was not the case with patients showing less substantial improvement. The importance of cognitions was discussed.We wish to express our thanks to Marijke Höweler-van Dalen for supervising this investigation, to Arnold Goedhart for statistical advice, to Dr. Orlebeke for his critical remarks, and to Dr. Penders for referring the patients in Amsterdam. We are particularly indebted to the general practitioners Paul Kreutzer and Jan Huls for referring the Andijk patients. Without their support this investigation would not have been possible.     

Baseline levels in muscle relaxation training

Variations in the baseline levels of physiological measures, a familiar problem in psychophysiological research, can affect the results of clinical applications and research in the self-control of bodily processes. In this presentation, the problem is illustrated within the context of skeletal muscle relaxation training using continuous biofeedback(BF) based on surface electromyographic(EMG) activity. In terms of the Law of Initial Values(LIV), higher EMG levels are expected to be associated with greater decreases during training. The combined results of two studies documented an LIV-like effect for pretraining baseline levels with greater EMG decreases after training for subjects with the higher pretraining baselines. Left uncorrected, such baseline differences were shown to lead to discrepant results between two identical studies, and therefore to conflicting conclusions about the effectiveness of these procedures. The available methods suggested to correct for the biasing effect of baseline differences in research are described, with particular emphasis on the analysis of covariance.This research was supported in part by NIH Grants MH24222 and AI-10398. The authors would like to thank Miss Sharon Robinson for supervising the collection of data and for her constructive comments regarding the training procedures of the studies described.     

Live and taped relaxation instructions: effects of procedural variables

Two experiments were designed to assess the effects of relaxation training, therapist presence or absence, live versus taped voice, and response-contingent versus noncontingent instructional progress on measures of subjective relaxation and frontal EMG. In the first experiment, it was found that subjects receiving taped instructions showed greater within-session subjective relaxation and lowering of within-session frontal EMG than subjects in a control condition. No differential training effects of therapist presence or absence was noted. In a second experiment, no significant differences in relaxation measures were found between subjects receiving live, response-contingent instructions and subjects receiving live, noncontingent instructions. Moreover, no meaningful differences in relaxation measures were found between subjects receiving live and taped instructions.     

Stress management techniques: Are they all equivalent,or do they have specific effects?

This article evaluates the hypothesis that various stress management techniques have specific effects. Studies comparing various techniques are reviewed, as well as previous literature reviews evaluating the effects of individual techniques. There is evidence that cognitively oriented methods have specific cognitive effects, that specific autonomic effects result from autonomically oriented methods, and that specific muscular effects are produced by muscularly oriented methods. Muscle relaxation and/or EMG biofeedback have greater muscular effects and smaller autonomic effects than finger temperature biofeedback and/or autogenic training. EMG biofeedback produces greater effects on particular muscular groups than progressive relaxation, and thermal biofeedback has greater finger temperature effects than autogenic training. Disorders with a predominant muscular component (e.g., tension headaches) are treated more effectively by muscularly oriented methods, while disorders in which autonomic dysfunction predominates (e.g., hypertension, migraine headaches) are more effectively treated by techniques with a strong autonomic component. Anxiety and phobias tend to be most effectively treated by methods with both strong cognitive and behavioral components.This work was supported by grants Nos. HL-34336 and HL-44097 from the Heart, Lung, and Blood Institute of the National Institutes of Health. Material in this article has been condensed and updated from three chapters in Lehrer, P. M., and Woolfolk, R. L. (1993).Principles and practice of stress management, Vol. 2, New York: Guilford Press.     

Effect of instruction,surface stability,and load intensity on trunk muscle activity

The aim of this study was to assess the effect of verbal instruction, surface stability, and load intensity on trunk muscle activity levels during the free weight squat exercise. Twelve trained males performed a free weight squat under four conditions: (1) standing on stable ground lifting 50% of their 1-repetition maximum (RM), (2) standing on a BOSU balance trainer lifting 50% of their 1-RM, (3) standing on stable ground lifting 75% of their 1-RM, and (4) receiving verbal instructions to activate the trunk muscles followed by lifting 50% of their 1-RM. Surface EMG activity from muscles rectus abdominis (RA), external oblique (EO), transversus abdominis/internal oblique (TA/IO), and erector spinae (ES) were recorded for each condition and normalized for comparisons. Muscles RA, EO, and TA/IO displayed greater peak activity (39–167%) during squats with instructions compared to the other squat conditions (P = 0.04–0.007). Peak EMG activity of muscle ES was greater for the 75% 1-RM condition than squats with instructions or lifting 50% of 1-RM (P = 0.04–0.02). The results indicate that if the goal is to enhance EMG activity of the abdominal muscles during a multi-joint squat exercise then verbal instructions may be more effective than increasing load intensity or lifting on an unstable surface. However, in light of other research, conscious co-activation of the trunk muscles during the squat exercise may lead to spinal instability and hazardous compression forces in the lumbar spine.     

Interaction of viscoelastic tissue compliance with lumbar muscles during passive cyclic flexion–extension

Human and animal models using electromyography (EMG) based methods have hypothesized that viscoelastic tissue properties becomes compromised by prolonged repetitive cyclic trunk flexion–extension which in turn influences muscular activation including the flexion–relaxation phenomenon. Empirical evidence to support this hypothesis, especially the development of viscoelastic tension–relaxation and its associated muscular response in passive cyclic activity in humans, is incomplete. The objective of this study was to examine the response of lumbar muscles to tension–relaxation development of the viscoelastic tissue during prolonged passive cyclic trunk flexion–extension. Activity of the lumbar muscles remained low and steady during the passive exercise session. Tension supplied by the posterior viscoelastic tissues decreased over time without corresponding changes in muscular activity. Active flexion, following the passive flexion session, elicited significant increase in paraspinal muscles EMG together with increase in the median frequency. It was concluded that reduction of tension in the lumbar viscoelastic tissues of humans occurs during cyclic flexion–extension and is compensated by increased activity of the musculature in order to maintain stability. It was also concluded that the ligamento-muscular reflex is inhibited during passive activities but becomes hyperactive following active cyclic flexion, indicating that moment requirements are the controlling variable. It is conceived that prolonged routine exposure to cyclic flexion minimizes the function of the viscoelastic tissues and places increasing demands on the neuromuscular system which over time may lead to a disorder and possible exposure to injury.