Feedback delays and relaxation expectancies in EMG biofeedback

The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.     

Feedback delays and relaxation expectancies in EMG biofeedback

The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.This study was completed by the first author under the direction of the second author in partial fulfillment of the requirements for the Master of Arts degree. We gratefully acknowledge the computerization advice and assistance provided by Larry Wheeler, and the assistance in data collection provided by Dawn Dexter and Michael Winstanley.     

Flexibility development in sprinters using EMG biofeedback and relaxation training

This study compared the effectiveness of electromyographic (EMG) biofeedback and relaxation treatment in producing flexibility increases at the hip joint. Retention of flexibility gains and changes in sprinting performance were also examined. Fifteen male and 15 female athletes, predominantly sprinters, were matched according to age, sex, and flexibility and were randomly assigned to one of three groups. The control group received only the testing, the biofeedback group received visual and auditory EMG training, and the relaxation group received modified PMR and imagery exercises. Subjects in the two experimental groups were given eight twice-weekly 10-minute sessions and then were retested for flexibility. Retention of flexibility was reassessed 2 and 4 weeks later. Sprint performance improved for all groups. EMG biofeedback and relaxation treatment methods were no more effective than stretching exercises used by the control group for improving flexibility during the treatment period, but they did produce evidence of superior flexibility gains in the retention period. This may be important as flexibility has been reported to be related to the incidence of injuries.     

Cognitive cost of motor reorganizations associated with muscular fatigue during a repetitive pointing task

Muscular fatigue is known to impair motor performance and to catalyse the development of upper limb musculoskeletal disorders. In order to delay the deleterious effects of muscular fatigue, the central nervous system (CNS) employs compensatory strategies. The cognitive cost of such compensatory strategies was assessed in 10 male subjects who alternatively performed two dual-task protocols before and immediately after an exhaustion procedure specific to upper arm abductor musculature. The main motor tasks were an isometric force-matching and a rapid multi-joint pointing. A secondary probe reaction time (RT) task was performed during both protocols and served as an indicator of attentional demands. Overall motor task performance was maintained despite fatigue. Kinematic and electromyographic data revealed that subjects used motor reorganization during the pointing task when fatigued. The RT increased with fatigue in both dual-task protocols, but this increase was significantly higher during the pointing task than during the force-matching task.The results highlight that the motor reorganization used by the CNS under muscular fatigue states require higher attentional demands than the initial motor organization. Finally, the capacity to delay the deleterious effects of muscular fatigue seems to depend on the proportion of cognitive resources available to plan the compensatory motor strategy.     

The response of manual motor functioning in Parkinsonians to frontal EMG biofeedback and progressive relaxation

The purpose of the current investigation was to determine the effects of frontal EMG biofeedback and progressive relaxation training on manual motor functioning in Parkinsonians. Twenty patients were matched and randomly assigned to two groups. All subjects were administered a brief manual motor assessment. The experimental group then underwent weekly sessions of frontal EMG and relaxation training for a period of 15 weeks. At the conclusion of the training period, both experimental and control groups were again administered the manual motor tasks. The results indicated that Parkinsonian patients are capable of significantly lowering frontal EMG activity levels. The motor task results, however, yielded no statistically significant differences between the two groups as a result of the biofeedback training.     

Effects of an EMG biofeedback relaxation program on the control of diabetes

It was hypothesized that EMG biofeedback relaxation training, applied to a diabetic patient, would result in a decreased level of insulin with fewer episodes of ketoacidosis. A 20-year-old female, diabetic since age nine, kept daily records of insulin doses and rated herself on an emotionality and a diabetic scale. A full-semester baseline was taken. This was followed by a semester-long training program during which the patient practiced relaxing her frontalis muscle with a portable EMG feedback unit which produced a geiger-counter-like click feedback. A cassette-tape series was used along with the portable EMG. The patient was encouraged to practice twice each day and to attempt to maintain a relaxed state even when not in the practice situation. The daily use of the portable unit was terminated at the end of the semester. In addition, the patient ceased practicing twice daily with the cassette tape. Daily insulin averaged 85 units for the six-week baseline and 59 for the final six weeks of the training period. Moreover, at the end of the training period the average dose had reached 43 units. During the training period the patient rated herself as decreasing in emotionality and in diabetic fluctuations.Supported by the National Institute of Mental Health Grant MH-15596.     

Cognitive skills training versus EMG biofeedback in the treatment of tension headaches

In an effort to study the role of cognitive skills training in the treatment of psychosomatic disorders, two single-case design experiments were conducted to assess the relative effectiveness of biofeedback procedures and cognitive coping techniques in the alleviation of tension headaches. For both subjects, biofeedback training influenced mean frontalis EMG levels, although such changes were not associated with concomitant reductions in headache activity. It was the presence or absence of cognitive skills training, however, that determined whether each subject reported changes in headache levels. These results suggest that a more efficient treatment approach for tension headaches would involve an increased emphasis on the modification of maladaptive cognitive activity. The present findings support the general view that a comprehensive approach in the treatment of stress-related disorders requires a concomitant focus on the cognitive, behavioral, and affective dimensions of the symptom. It was also suggested that biofeedback technology may be a useful tool for studying the physiological consequences of particular cognitive processes and in identifying particular cognitions with anxiety-provoking properties.     

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 less than .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, aggresion). 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.     

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.     

A comparison of frontal EMG biofeedback and neck EMG biofeedback in the treatment of muscle-contraction headache

EMG biofeedback from the frontal area (FFB) was compared to EMG biofeedback from the neck (NFB) in the treatment of chronic muscle-contraction headache. Both treatment groups (N=10) evidenced significant decreases in reported headache activity, with the NFB group also significantly reducing medication consumption. An analysis of EMG changes suggested that subjects were able to produce large within-session changes in EMG activity during initial sessions, with the major effect of additional training being an increase in speed with which these changes occurred. In neither group, however, did changes in EMG activity correspond closely to changes in reported headache activity.     

Effectiveness of multiple muscle-site EMG biofeedback and relaxation training in reducing the aversiveness of cancer chemotherapy

A 44-year-old female cancer patient was given progressive muscle relaxation training and multiple muscle-site EMG biofeedback to reduce the conditioned negative responses she had apparently developed to her chemotherapy treatments. Following three baseline chemotherapy sessions, the patient was given relaxation training and biofeedback during four consecutive chemotherapy treatments and was asked to practice her relaxation skills daily in the hospital or at home. After the patient felt able to relax on her own, relaxation training and biofeedback were terminated and three follow-up sessions were held. Results indicated that during the chemotherapy sessions in which the patient received relaxation training and biofeedback, she showed reductions in physiological arousal (EMG, pulse rate, systolic blood pressure, and diastolic blood pressure) and reported feeling less anxious and nauseated. Moreover, these changes were maintained during the follow-up sessions. These results suggest that relaxation training plus multiple muscle-site biofeedback may be an effective adjunctive procedure for reducing some of the adverse side effects of cancer chemotherapy.     

Using biofeedback to reduce left arm extensor EMG of string players during musical performance

Electromyographic (EMG) feedback offers a mechanism for helping musicians reduce specific muscle tension during performance. Nine intermediate to advanced level string players participated in a four-session, pretest/posttest design study to determine (1) if left forearm extensor EMG could be reduced using biofeedback, (2) if reductions in EMG would generalize to a no-feedback condition, and (3) if reductions in EMG would generalize from extensors to flexors. Results indicate that biofeedback did facilitate significant decreases in EMG, that the reductions in EMG did generalize to a no-feedback condition, and that generalization from extensors to flexors did not occur.     

Specific and nonspecific effects of EMG biofeedback

This study investigated the effects of performance feedback and EMG biofeedback on perceptions of the self (i.e., self-esteem, self-control, self-efficacy, and locus of control) as well as on a self-control behavior (study skills) the subjects performed outside the laboratory. Forty-seven college students were randomly assigned to one of four groups in a 2(high and low success feedback) × 2(true and false EMG biofeedback) factorial experiment with repeated measures. All of the participants received four sessions of EMG biofeedback, and later they were asked to self-monitor their study habits for 2 weeks. Results showed that the self-esteem measure and perceptions of study skills improvement were differentially affected by success feedback but unrelated to the true or false EMG manipulation. Shifts toward an internal locus of control and perceptions of improved self-control were also noted, but they were independent of the subjects' group membership. Implication of the results are briefly discussed.     

Generalization of lowered EMG levels during musical performance following biofeedback training

Electromyographic (EMG) biofeedback training offers a means by which musicians can control excess muscle tension during performance. Music instructors generally agree that unnecessary muscle tension not only leads to physical problems but also can interfere with performance quality. It is important, however, that the reduced EMG levels resulting from biofeedback training generalize to situations in which feedback is not available, and that the reduction in muscle tension not result in decreased performance quality. Eight intermediate to advanced clarinet players participated in four EMG biofeedback training sessions during which short-term and extended generalization of lowered EMG levels was assessed along with trill and scale speed scores. Significant reductions in EMG levels associated with biofeedback training generalized to short-term and extended situations, while trill and scale performances remained at or above pretest levels.     

Specific and nonspecific effects of EMG biofeedback

This study investigated the effects of performance feedback and EMG biofeedback on perceptions of the "self" (i.e., self-esteem, self-control, self-efficacy, and locus of control) as well as on a self-control behavior (study skills) the subjects performed outside the laboratory. Forty-seven college students were randomly assigned to one of four groups in a 2(high and low success feedback) x 2(true and false EMG biofeedback) factorial experiment with repeated measures. All of the participants received four sessions of EMG biofeedback, and later they were asked to self-monitor their study habits for 2 weeks. Results showed that the self-esteem measure and perceptions of study skills improvement were differentially affected by success feedback but unrelated to the true or false EMG manipulation. Shifts toward an internal locus of control and perceptions of improved self-control were also noted, but they were independent of the subjects' group membership. Implication of the results are briefly discussed.     

Unchanged H-reflex during a sustained isometric submaximal plantar flexion performed with an EMG biofeedback

The aim of this study was to assess H-reflex plasticity and activation pattern of the plantar flexors during a sustained contraction where voluntary EMG activity was controlled via an EMG biofeedback. Twelve healthy males (28.0 ± 4.8 yr) performed a sustained isometric plantar flexion while instructed to maintain summed EMG root mean square (RMS) of gastrocnemius lateralis (GL) and gastrocnemius medialis (GM) muscles fixed at a target corresponding to 80% maximal voluntary contraction torque via an EMG biofeedback. Transcutaneous electrical stimulation of the posterior tibial nerve was evoked during the contraction to obtain the maximal H-reflex amplitude to maximal M-wave amplitude ratio (H_sup/M_sup ratio) from GL, GM and soleus (SOL) muscles. Neuromuscular function was also assessed before and immediately after exercise. Results showed a decrease in SOL activation during sustained flexion (from 65.5 ± 6.4% to 42.3 ± 3.8% maximal EMG, p < 0.001), whereas summed EMG RMS of GL and GM remained constant (59.7 ± 4.8% of maximal EMG on average). No significant change in the H_sup/M_sup ratio was found for SOL, GL and GM muscles. Furthermore, it appears that the decrease in maximal voluntary contraction torque (?20.4 ± 2.9%, p < 0.001) was related to both neural and contractile impairment. Overall, these findings indicate that the balance between excitation and inhibition affecting the motoneuron pool remains constant during a sustained contraction where myoelectrical activity is controlled via an EMG biofeedback or let free to vary.     

Hypnotizability and response to EMG relaxation training

This study examines the relationship between Spiegel's Hypnotic Induction profile (HIP) and ability to perform EMG relaxation under conditions of self-induced and audio-assisted biofeedback training. One hundred women volunteered for screening with Spiegel's test for hypnotizability. Thirty students were then selected from the top, middle, and bottom of the HIP scoring distribution for EMG biofeedback training in relaxation. Three treatment trials included baseline, EMG biofeedback with self-induced relaxation, and EMG biofeedback with audio relaxation instructions. Contrary to predictions, high HIPs were not significantly different from low HIPs on any of the treatment measures, although all students showed a training effect. The middle HIPs demonstrated significantly higher levels of EMG activity than the extreme groups.     

The effect of stressful life events on EMG biofeedback and relaxation training in the treatment of anxiety

The present study evaluated the effect of frontal EMG biofeedback and relaxation training on a group of 20 anxious patients experiencing stressful life events. The patients were divided into two groups, high and low in stress, based on their life change score on the Recent Life Changes Questionnaire. Patients were evaluated at pre, post, and 6-week follow-up. Treatment consisted of 10 sessions of biofeedback-assisted relaxation. Results indicated that the high stress group showed pre to post changes on anxiety, depression, symptoms, and EMG, while low stress showed no change. Post to follow-up comparisons showed maintenance of improvement for the high stress group and no change for low stress. From pre to follow-up assessment, the high stress group showed significant changes. Both groups reported internal attributions following biofeedback and relaxation training. The high stress group attributed their improvement to the belief they were in control of their minds and bodies, while the low stress group most frequently reported the effort put into the task. The results indicate support for a cognitive explanation for some of biofeedback's effects.     

Effect of mechanomyography as a biofeedback method to enhance muscle relaxation and performance

The purpose of the study was to examine the potential for using the mechanomyographic (MMG) signal as a biofeedback method to enhance muscular relaxation and to improve performance during forearm flexion repetitions to fatigue. Twelve adult (mean +/- SD; age: 22.0 +/- 1.1 years) moderately trained subjects (weight: 82.3 +/- 29.2 kg; height: 165.7 +/- 49.0 cm) were instructed to relax the biceps brachii muscle using MMG biofeedback (BIO) provided by viewing a computer screen graphically displaying the MMG signal and then without using MMG biofeedback (NOBIO). Electromyographic (EMG) and MMG signals were detected midway over the biceps brachii during the relaxation protocol. In subsequent visits to the laboratory, subjects performed as many repetitions as possible at 85% of 1 repetition maximum with BIO and NOBIO using the seated preacher curl exercise. Two-way (biofeedback x gender) mixed factorial analyses of variance revealed significantly (p < 0.05) lower MMG (mean +/- SEM; BIO = 0.6 +/- 0.1 mV; NOBIO = 1.1 +/- 0.2 mV) and EMG amplitudes (BIO = 6.6 +/- 0.6 microV; NOBIO = 9.4 +/- 1.4 microV) for BIO when subjects were instructed to relax the biceps brachii muscle. There was no significant difference in the number of forearm flexion repetitions performed for BIO (mean +/- SD; 7.9 +/- 0.4 reps) vs. NOBIO (8.1 +/- 0.6 reps). The results of the present study revealed that using MMG as a biofeedback technique can enhance the development of muscle relaxation, but is not useful in delaying fatigue during forearm flexion repetitions. Our results may have been influenced by a relatively short training phase designed to teach subjects to use the MMG signal as a biofeedback method. Future studies are needed to determine whether MMG biofeedback can be used for other purposes. If MMG is found to be useful as a biofeedback method, it has some distinct practical advantages over EMG that the strength and conditioning athlete and professional may find appealing.