Generalization of EMG biofeedback training

Five young adults received audio biofeedback training to reduce trapezius EMG levels while they engaged in reading in an office, seated at a table. A multiple-baseline-across subjects design was employed in two separate studies. After training, all subjects demonstrated reduced EMG levels while reading in a home or library setting. The first study suggested that subjects reduced EMG levels by minimizing movements and altering their postures; the second study systematically demonstrated changes in such behavior, which was correlated with EMG levels. The data provide evidence that EMG biofeedback resulted in response generalization across several motoric classes, and in stimulus generalization from the training setting to the natural environment. The importance of assessing generalization is discussed.     

EMG stability as a biofeedback control

Factors that may confound comparisons between electromyographic (EMG) biofeedback training and its control conditions include feedback quality and experience of success. We investigated the usefulness of a control procedure designed to overcome these potential sources of confounding. The procedure consisted of training muscle tension stability. We used it as a control for frontal EMG relaxation training in children with asthma. To equate the groups for feedback quality and experience of success, we gave each child in the control condition audio feedback decreasing in pitch when muscle tension was at or near baseline levels, and feedback increasing in pitch when muscle tension was either substantially above or below baseline levels. Children in both groups were instructed to decrease the pitch of the tone. In comparison to children in the relaxation condition, the children in the control condition exhibited stable levels of muscle tension throughout eight training sessions. We concluded that feedback for stable muscle tension may be a useful control procedure for EMG biofeedback training whenever experimental and control procedures differ in either feedback quality of degree to which they permit subjects to experience success.This research was supported by NIH-Grant HL 27402. We are grateful to Paul Schnitter who constructed the EMG stability feedback device.     

Yawning: A possible confounding variable in EMG biofeedback studies

An elderly hemiplegic patient participating in an EMG biofeedback training program was observed to produce a synergistic flexion movement of the plegic (determined by functional evaluations) upper limb while yawning. In the course of the training sessions the electrical activity of the anterior deltoid (the target muscle) was recorded during yawning. These peak EMG values were greatly facilitated in comparison with the session mean peak values obtained during an attempted maximum voluntary isometric contraction (shoulder flexion) of the same limb (e.g., Trial 1: 85.00 vs. 4.33 µV). The possibility of yawning as a confounding variable in EMG biofeedback studies is presented and discussed.This research was supported in part by Health and Welfare Canada (NHRDP).     

The role of EMG awareness in EMG biofeedback learning

Underlying most research on biofeedback learning is a theoretical model of the processes involved. The current study tested a prediction from the Awareness Model: High initial EMG awareness should facilitate response control during EMG biofeedback training. Seventy-two undergraduates were assessed for forehead EMG awareness by asking them to produce target responses from 1.0 to 5.0 µV every 15 s for 16 trials. Based on this assessment, two groups (high and low awareness) were trained for 64 trials to produce these target levels with either EMG biofeedback, practice (no feedback), or noncontingent EMG feedback. A transfer task was identical to the initial assessment. During training, the biofeedback group deviated less from target than the practice and noncontingent groups. The biofeedback group was the only group to improve from initial EMG awareness activity. During transfer, only the low awareness biofeedback group remained below initial EMG awareness level. These findings can be interpreted in terms of the Two-Process Model.     

Frequency characteristics of signals and instrumentation: Implication for EMG biofeedback studies

Signals can be analyzed in either the time or frequency domain. In the time domain, the analysis consists of manipulating and measuring one or more characteristics of the signal that may vary with time. One can, for instance, rectify a signal, filter it, calculate its mean value, display the histogram of its amplitude, and so forth. Frequency analysis is less well understood because it requires a lengthy mathematical treatment most easily done by computer. However, it gives exclusive information on a signal. For instance, when the frequency content of a signal is known, it is easy to specify which characteristics an amplifier must have in order to amplify the signal without distortion, or to set the cutoff frequencies of filters to eliminate noise. Also, in many circumstances, frequency spectra are more easily interpreted than the original raw data. Such is the case with the EMG where the random aspect of the signal makes some form of processing (i.e., rectification, filtering, etc.) necessary, but not always as meaningful as we would like. Thus we present here the principal characteristics of frequency analysis, and discuss its usefulness in analyzing EMG signals and its application to biofeedback, clinical practice, and research.The authors acknowledge the technical assistance of F. Kemp, M. Goyette, and C. Goulet. T. Milner kindly reviewed the final version of the text. The preparation of this paper was supported through funds from Health and Welfare Canada (NHRDP) and the Centre de recherche, Institut de réadaptation de Montréal.     

The use and utility of EMG biofeedback with chronic schizophrenic patients

This study examined the efficacy of muscle relaxation training via electromyographic (EMG) biofeedback from the frontalis and forearm extensor muscles of schizophrenic inpatients. Thirty chronically hospitalized patients were randomly assigned to one of three conditions: EMG biofeedback from the forearm extensor and frontalis muscles, progressive relaxation, and a control group. Treatment consisted of one session of orientation and baseline, and six sessions of training. The results indicated that the schizophrenic patients receiving EMG training had significantly lower EMG recordings than the progressive relaxation group, which, in turn, was significantly lower than the control group. Analyses of covariance on the Tension-Anxiety scale from the Profile of Mood States revealed no significant effects, while finger-tapping rates were significantly improved only for the arm receiving feedback training in the EMG group. On the Nurses Observation Scale for Inpatient Evaluation the biofeedback group significantly improved on the Social Competence and Social Interest factors.We would like to express our appreciation for the contributions the following people made to this project: Drs. Barry Smith, Robert Steele, Agnes Hartfield, Jeffrey Barth, Althea Wagman, and the late Harold Weiner; Earl Downs and the participating staff at Springfield State Hospital Center; and Robert Kline and Michael Kelley, who performed the data analyses. This research was supported in part by a grant from the Computer Science Center at the University of Maryland.     

Electromyographic biofeedback training for tension headache in the elderly: A prospective study

This study evaluated the effects of a 12-session frontal electromyographic biofeedback training regimen on the headache activity of eight tension headache sufferers aged 62 and older. The biofeedback sessions were slightly modified for a geriatric population, essentially to increase comprehension and retention of rationale and instructions. Post-treatment assessment at three months revealed significant decreases in overall headache activity (50% or greater) in 50% of the subjects, and moderate improvement (35%–45%) in three of the remaining four subjects. Significant clinical and/or statistical prepost differences were also found for the number of headache-free days, peak headache activity, and medication index. This is the first prospective study of biofeedback training for tension headache in an elderly population and, unlike previous retrospective studies, suggests that such therapy may be an effective intervention in the treatment of tension headaches in the elderly.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the United States Department of Veterans Affairs. This study was supported by a Department of Veterans Affairs MERIT-Review awarded to the first author.     

Variations in digital temperature during frontal EMG biofeedback training in normal subjects

During frontal EMG biofeedback training, the relationship between frontal EMG and digital skin temperature was investigated in two experiments, which varied the number of baseline and feedback sessions. The results of Experiment 1 suggested a "general relaxation effect," where digital temperature increased as frontal EMG decreased, especially for subjects with initially low hand temperature. Experiment 2 extended the number of baseline and feedback sessions and qualified the results of Experiment 1. EMG and digital temperature did not simultaneously converge toward general relaxation over the extended baseline or feedback sessions in Experiment 2. Furthermore, when the feedback signal was introduced, digital temperature dropped quickly but recovered to baseline levels within three feedback sessions; this drop in digital temperature was interpreted within the context of attentional demands of the biofeedback task. The results appeared consistent with the view that frontal biofeedback training teaches a discriminative skill of lower frontal EMG, and that this skill does not readily generalize to digital skin temperature.     

Physiological mechanism of digital vasoconstriction training

Recent work in our laboratory has shown that vasodilation produced during temperature biofeedback training is mediated through a nonneural, beta-adrenergic mechanism. Here we sought to determine if the effects of feedback training for vasoconstriction are produced through a neural or nonneural pathway and whether other measures of physiological activity are correlated with these changes. Nine normal subjects received temperature feedback vasoconstriction training in which feedback was delivered only during periods of successful performance. In a subsequent session, the nerves to one finger were blocked with a local anesthetic while finger blood flow was recorded from this and other fingers. Vasoconstriction occurred during feedback in the intact fingers but not in the nerve-blocked finger and was accompanied by increased skin conductance and heart rate. These data demonstrate that temperature feedback vasoconstriction training is mediated through an efferent, sympathetic nervous pathway. In contrast, temperature feedback vasodilation training is mediated through a nonneural, beta-adrenergic mechanism.This work was supported by research grant HL-30604 from the National Heart, Lung, and Blood Institute.     

Scientific and clinical biofeedback in the USSR

This paper describes the history of biofeedback research and application in the USSR. The approach of USSR scientists to the study of basic mechanisms of biofeedback and the status of clinical applications of biofeedback in the Soviet Union are described. Trends in the publication of biofeedback-related papers in Russian are presented, and the present state of the art described. Promising prospects for biofeedback research and application are discussed.     

Subjective experiences associated with thermal biofeedback treatment of hypertension

Reports of subjective experiences of 73 hypertensive patients who were treated with thermal biofeedback for hand warming were obtained over 16 treatment sessions. Most of the differential responding in subjective report occurred in the first 5 sessions. Differences in reports of throbbing were associated with medication status during treatment (presence of sympatholytic antihypertensive agent). From 4 to 9% of patients report negative subjective experiences at any one session. When short-term clinical successes (either elimination of medication or reduction of BP) were compared with short-term failures, it was found that successes reported more warmth, more likelihood of falling asleep, and more dreamlike experiences. The latter were more likely to occur suddenly for the successes. Correlational analyses revealed consistent positive associations between reports of warmth and relaxation with highest temperature achieved in the session and consistent negative associations between experiencing physical sensations and degree of temperature change within the session.This research was supported in part by grants from NHLBI, HL-27622 and HL-31189.     

Fifteen-month follow-up with asthmatics utilizing EMG/Incentive inspirometer feedback

This study reports on the follow-up data of an integrated group program to reduce asthmatic symptoms. The 16 sessions included a comprehensive multibehavioral/desensitization retraining program and utilized EMG/Incentive inspirometer feedback to encourage slow diaphragmatic breathing in all situations. 17 out of 21 volunteers participated in the 15-month follow-up study. At the follow-up all subjects significantly reduced their EMG tension levels while simultaneously increasing their inhalation volumes. Subjects reported reductions in their asthma symptoms, medication use, emergency room visits, and breathless episodes.We thank Ms. Michelle Roland, Kathy Smith, and Jeanne Charbonneau for their helpful assistance.     

Biofeedback-assisted relaxation training for the aging chronic pain patient

The older segments of the U.S. population are expanding rapidly and account for a disproportionate amount of health care, including treatment for pain-related musculoskeletal disorders. In a prospective study with objective measures and one-year follow-up, Middaugh et al. (1988) found that older patients (55–78 yr; N=17, 76% success) treated in a multidisciplinary chronic pain rehabilitation program enjoyed a success rate equal to that of younger patients (29–48 yr; N=20, 70% success). The current study presents additional data on these two groups of patients to compare their ability to learn the physiological self-regulation skills taught in the biofeedback/relaxation component of the multimodal program. This component included progressive muscle relaxation training, diaphragmatic breathing instruction, and EMG biofeedback. Repeated measures ANOVA showed significant increases in digital skin temperature (peripheral vasodilation) and decreases in respiration rate both within and across training sessions (p values=.04 to .0001) with no differences between age groups (p>.05). EMG measures for the upper trapezius ms in patients with cervical pain showed similar deficits in muscle control at evaluation and similar improvements with biofeedback training for the two age groups. These findings indicate that older pain patients responded well to the biofeedback/relaxation training component of the multimodal pain program.This research was supported in part by NIDRR grant No. H133G90085, Department of Education, DHEW, and by the Medical University of South Carolina General Clinical Research Center under NIH grant No. RR1070.     

The use of biofeedback in a behavioral program designed to teach an anxious child self-catheterization

This paper presents a case study of a 7-year-old girl with a noncompliant bladder who was trained to self-catheterize using biofeedback and behavior therapy techniques. Initial attempts to train her to self-catheterize were unsuccessful owing to excessive amounts of fear, muscle tension, and refusal. After seven treatment sessions in which she was instructed in proper self-catheterization technique by a urology nurse clinician and coached in biofeedback-assisted relaxation by a clinical psychologist, the child successfully learned to self-catheterize. EMG readings showed a decrease in quadriceps muscle tension levels across sessions. Eight additional sessions were held in order to train the child's parents in proper technique and coaching procedures. Through the use of portable biofeedback equipment during actual training sessions, the biofeedback served as a cue—first to the child and coach, and later to the child and parents—for when the child needed to stop and relax. This case illustrates the usefulness of biofeedback in a comprehensive behavioral program designed to teach self-catheterization to fearful children.     

Evaluation of home-based thermal biofeedback treatment of pediatric migraine headache

Sixteen children and adolescents with migraine headache were treated with thermal biofeedback. Seven were seen individually in the clinic while the other nine participated in a limited-contact, partly home-based regimen. Evaluation of headache diary data from 4-week monitoring periods before and after treatment showed significant (p<.01) reduction in headaches, with no significant difference in efficacy between the two conditions.This research was supported in part by grants from NIMH, MH-41341, and NINCDS, NS-23440.     

The effects of thermal biofeedback and autogenic training of cardiovascular reactivity: The joint USSR-USA behavioral hypertension treatment project

Cardiovascular reactivity (heart rate, systolic, and diastolic BP) to mental arithmetic and cold pressor were measured before and after treatment as part of the cross-cultural (USSR and USA) evaluation of thermal biofeedback and autogenic training (in comparison with self-relaxation) as treatments for mild hypertension in unmedicated males. There were no statistically reliable decreases in cardiovascular reactivity from before to after treatment. However, downward shifts in basal levels of systolic and diastolic BP at post-treatment led treated patients to have lower stress-induced levels of BP.The American portion of this research was supported by a grant from the NHLBI, HL-31189. We express appreciation to officials at the USSR Cardiology Research Center, Academician Igor Shkhvatsabaya, and Professor Vadim Zaitsev for their support, as well as to Dr. Steve Weiss, of NHLBI, for his instigation of this research.     

Growth and development of biofeedback: A bibliographic update

Computerized literature searching techniques were used to examine publication patterns in the worldwide biofeedback literature. Searches were completed in the United States and in Japan for the years 1985 through 1987. The results were used to update the results of an earlier study (Hatch & Riley, 1985) that covered the years from 1964 through 1984. Publication growth curves were generated for several media, including scientific journal articles, books, doctoral dissertations, and popular magazine articles. Although publication of information about biofeedback remains active worldwide, there has been a declining trend in effect for the past several years. The American database grossly underestimated the number of Japanese biofeedback articles, and it is likely that the literatures of other countries outside of North America were similarly underestimated. Possible explanations for the various trends noted are discussed.These results were presented in part at the Twentieth Annual Meeting of the Association for Applied Psychophysiology and Biofeedback. We gratefully acknowledge the assistance of Margaret Cyr-Provost in preparing the data for analysis.