This unit addresses VI. HRV Applications: A. Clinical applications, and B. Optimal performance applications.
This unit covers The Clinical Efficacy of Established Medical Practices, Criteria for Clinical Efficacy, Overview of HRV Biofeedback Efficacy, Asthma, Chronic Obstructive Pulmonary Disease (COPD),
Depression, Fibromyalgia (FM), Chronic Muscle Pain, Coronary Artery Disease, Essential Hypertension, Preeclampsia, Anxiety, Phobia, and Post-Traumatic Stress Disorder (PTSD), Functional Abdominal Pain, Irritable Bowel Syndrome, and Optimal Performance.
Please click on the podcast icon below to hear a full-length lecture.
The Clinical Efficacy of Established Medical Practices
Prasad et al. (2013) examined 363 studies of an accepted drug or medical procedure published in The New England Journal of Medicine from 2001 to 2010. More than 40% were ineffective or harmful, 38% were beneficial, and 22% had uncertain value.
Examples of ineffective or harmful practices included hormone replacement therapy in post-menopausal women and aggressive blood sugar reduction in Type 2 diabetics treated in intensive care, which increased mortality rates.
The authors observed: “Nevertheless, the reversals we have identified at the very least call these practices into question. Some practices ought to be abandoned, whereas others warrant retesting in more powerful investigations. One of the greatest virtues of medical research is our continual quest to reassess it.” (p. 796)
Criteria for Clinical Efficacy
The core membership organizations in our field have developed efficacy guidelines and have engaged in an ongoing assessment of clinical and optimal performance practices. There have been four editions of Evidence-Based Practice in Biofeedback and Neurofeedback, multiple White Papers, and literature reviews by Wheat and Larkin (2010) and Gevirtz (2013) of HRV applications.
The following guidelines for evaluating the clinical efficacy of biofeedback and neurofeedback interventions were recommended by a joint Task Force and adopted by the Boards of Directors of the Association for Applied Psychophysiology (AAPB) and the International Society for Neuronal Regulation (ISNR) (LaVaque et al., 2002).
HRV Biofeedback Efficacy
The empirical support for HRVB is impressive and growing. Unlike the medical practices reviewed by Prasad et al. (2013), no mainstream HRVB application is harmful or ineffective. HRVB outcome research is in its infancy, and researchers have yet to evaluate its full potential.
Lehrer and Colleagues' Systematic Review and Meta-Analysis
Lehrer and colleagues' (2020) systematic review and meta-analysis of 58 papers concluded:
A significant small to moderate effect size was found favoring HRVB, which does not
differ from that of other effective treatments. With a small number of studies for each, HRVB has the largest effect sizes for
anxiety, depression, anger and athletic/artistic performance and the smallest effect sizes on PTSD, sleep and quality of life.
We found no significant differences for number of treatment sessions or weeks between pretest and post-test, whether the
outcome measure was targeted to the population, or year of publication. Effect sizes are larger in comparison to inactive than
active control conditions although significant for both. HRVB improves symptoms and functioning in many areas, both in
the normal and pathological ranges. It appears useful as a complementary treatment.
Gevirtz's Hypothetical Mechanisms for HRV Biofeedback Applications
Although a Powerful Tool, Biofeedback is Not a Panacea
Dr. Inna Khazan summarized the lessons she learned from a challenging clinical case.
McGrady and Moss' Pathways Model
Although the BCIA HRV Biofeedback Blueprint does not cover the Pathways Model, it is a useful framework for clinical and performance interventions.
McGrady and Moss' (2013) Pathways Model rejects the concept of most illness as a discrete event: "Rather it is truly a pathway, a process involving a continuum from complete health to mild insufficiencies, to concerning deficiencies, and to diagnosed disease. Mainstream health care, which identifies a problem to address only when the individual's health is grossly impaired and diagnostic criteria are met, misses multiple opportunities to intervene in less expensive ways and to sustain optimal wellness" (p. 4).
"The aim of the Pathways Model is twofold: (1) to educate healthcare professionals and the general public to recognize earlier on the signs that one is on a pathway directed toward illness, allow one to correct that path earlier in the process, and (2) to assist those already in a state of disease to identify those past and present lifestyle choices and turning points, which have contributed to the onset and escalation of the disease, and to discover new choices and well behaviors to enable recovery of health" (p. 4).
The Pathways Model identifies three intervention levels. Each successive level builds on the preceding one. Level One interventions, which a client can develop and implement, restore disrupted biological rhythms.
Level Two interventions build on the platform provided by Level One interventions. They teach basic skills needed for psychological and physical health. They may be taught using educational (e.g., books and podcasts) and community resources (e.g., classes).
Level Three interventions build on the foundation provided by Level One and Level Two interventions. Most of these interventions will be directed by a professional.
The Pathways Model recognizes that mindfulness and motivation to change your "path" must develop progressively and that clients have self-care options (Level One and Two Interventions) that may restore health and promote optimal functioning without recourse to professional care (Level Three Interventions). Alternatively, they may provide a foundation that can make clinical interventions more effective. We invite the reader to read their excellent text, Pathways to Illness, Pathways to Health, and use their model when considering biofeedback treatment for the disorders reviewed in HRV Biofeedback Tutor.
The Global Initiative for Asthma (2018) defined asthma as a "...heterogenous disease, usually characterized by chronic airway inflammation. It is defined by the history of respiratory symptoms, such as wheeze, shortness of breath, chest tightness, and cough that vary over time and in intensity, together with variable expiratory limitation."
Asthma is a chronic inflammatory disease of the airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing. It's thought to be caused by a combination of genetic and environmental factors. The pathomechanics of asthma can be broken down into three primary components: inflammation, bronchial hyperresponsiveness, and airflow obstruction (Papadopoulos et al., 2012).
Inflammation: In asthma, the airways are persistently inflamed. This inflammation is driven by an abnormal immune response. When an asthmatic individual is exposed to a trigger (e.g., allergens, viral infections, cold air), certain immune cells (like T-helper 2 cells) produce pro-inflammatory cytokines, leading to an influx of other inflammatory cells (like eosinophils), which cause damage to the airway tissues (Draijer et al., 2016).
Bronchial Hyperresponsiveness: The inflamed airways become hyperresponsive or hypersensitive to various stimuli such as allergens, cold air, exercise, or emotional stress. This heightened sensitivity leads to an exaggerated bronchoconstrictor response, causing the smooth muscle that surrounds the airways to contract and narrow excessively (Kudo et al., 2013).
Airflow Obstruction: The combination of inflammation-induced swelling, excess mucus production, and bronchoconstriction narrows the airways and leads to the obstruction of airflow. This causes the characteristic symptoms of asthma - coughing, wheezing, shortness of breath, and chest tightness (Holgate, 2012).
Asthma severity and control can vary over time, and treatment aims to reduce inflammation, relieve symptoms, and prevent exacerbations. Nurses play a vital role in educating patients about their disease, the importance of avoiding triggers, and correct use of their medications.
HRV Biofeedback for Asthma
Clinicians have used heart variability (HRV) biofeedback with breathing retraining to reduce asthma symptom frequency and severity, improve pulmonary function, and reduce medication use. Lehrer and colleagues' (2000) protocol combines resonance frequency HRVB with abdominal pursed-lips breathing. The resonance frequency is when maneuvers like paced breathing can stimulate an individual's cardiovascular system to produce the greatest respiratory sinus arrhythmia (RSA).
Randomized Controlled Trials
Lehrer and colleagues (1997) studied 17 asthma patients, dividing them into three groups: those receiving HRVB, those undergoing EMG biofeedback-assisted relaxation with abdominal breathing, and a waiting list group. After 3 months, only the HRVB group saw a decrease in respiratory resistance.
Lehrer et al. (2004) divided 64 asthma patients, half receiving HRVB and the rest split between a placebo group and a waiting list. After 3 months, the HRVB group showed reduced respiratory resistance, lower medication usage, and fewer asthma flare-ups, improving one clinical grade.
Asthma symptoms lessened in both the biofeedback and placebo groups, but the reduction in asthma severity was more significant in the biofeedback group.
A re-analysis by Lehrer et al. (2006) showed that HRVB was equally beneficial for older and younger participants, despite smaller HRV increases in the older group.
Feldman et al. (2016) studied 53 asthma patients who also had panic disorder, providing a comprehensive program that included HRVB. They found greater improvements in panic control and adherence to inhaled steroids in the biofeedback group, though not in self-reported asthma control.
Lehrer et al. (2018) compared HRVB with a stress management treatment for 68 steroid-naïve asthma patients. Both treatments resulted in symptom reduction, but airway inflammation decreased only in the HRVB group.
Finally, Taghizadeh et al. (2019) found that a single session of HRVB reduced the pulmonary impact of stress-induced asthma exacerbations in 22 women diagnosed with asthma and 22 women without asthma.
Clinical Efficacy
Based on five RCTs, Lehrer, Moritz, and Greenfield (2023) rated HRVB for asthma as level 5 - specific and efficacious in Evidence-Based Practice in Biofeedback and Neurofeedback (4th ed.).
Participants improved in asthma severity and symptoms, pulmonary function, and medication use. The impact of HRVB on airway inflammation is uncertain.
Chronic Obstructive Pulmonary Disease (COPD)
Chronic obstructive pulmonary disease (COPD) is a family of lung diseases
that interfere with airflow. The Global Initiative for Chronic Obstructive Lung Disease (2019) definite it as "...a common preventable and treatable disease characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases."
COPD may affect 32 million patients in the United States and is the fourth leading cause of death. Patients are often diagnosed with chronic bronchitis and emphysema, and the classic triad adds asthma (Kleinschmidt, 2020).
Pathomechanics
Chronic obstructive pulmonary disorder (COPD) is a progressive disease characterized by airflow obstruction that is typically not fully reversible. The pathomechanism of COPD is complex and involves several interrelated processes.
Inflammation: Chronic exposure to noxious particles and gases, most commonly tobacco smoke, causes chronic inflammation in the airways and lung tissue. This inflammation leads to structural changes and narrowing of the small airways and destruction of the lung parenchyma, known as emphysema. This is characterized by an influx of various inflammatory cells including neutrophils, macrophages, and lymphocytes (Barnes, 2016).
Oxidative Stress: Oxidative stress plays a critical role in the pathogenesis of COPD. Cigarette smoke and other irritants increase the production of reactive oxygen species (ROS) which can damage proteins, lipids, and DNA in the lung cells. This can lead to cellular dysfunction, apoptosis, and emphysema (Rahman & Adcock, 2006).
Protease-Antiprotease Imbalance: In a healthy lung, there is a balance between proteases and antiproteases. In COPD, this balance is disrupted due to an increased protease activity (such as elastase) and/or decreased antiprotease activity (such as alpha-1 antitrypsin). This imbalance can lead to destruction of elastin in the lung tissue, contributing to emphysema (Barnes, 2016).
Airway Remodeling: Chronic inflammation and injury lead to structural changes in the airways, known as airway remodeling. This includes goblet cell hyperplasia (increased mucus production), squamous metaplasia (change in the type of cells lining the airways), and fibrosis (thickening and scarring of the airway walls), all contributing to airflow limitation (Jeffery, 2001).
Impaired Gas Exchange: The emphysematous destruction of the alveoli, along with chronic bronchitis, leads to impaired gas exchange. This can result in hypoxemia (low blood oxygen) and hypercapnia (high blood carbon dioxide), causing dyspnea and reduced exercise tolerance (O'Donnell et al., 2008).
Multimodal Interventions
Clinicians combine HRVB with exercise and paced breathing instruction to increase ventilation and exercise tolerance.
Randomized Controlled Trials
Several of these studies incorporated SPB with respiratory feedback.
Estève et al. (1996) demonstrated that breathing-pattern training sessions in addition to traditional rehabilitation sessions led to significant improvements in forced expiratory volume (FEV1) and forced vital capacity (FVC) in COPD patients.
Collins et al. (2008) found that visual feedback of breathing patterns led to increased breathing efficiency, improved exercise tolerance, and reduced hyperinflation in COPD patients. However, a subsequent study in 2019 by the same authors found no difference in outcomes between exercising with and without a metronome-like breathing pacer, suggesting the importance of real-time feedback in achieving better results.
Van Gestel et al. (2012) found that biofeedback for breathing in COPD patients did not affect exercise tolerance, quality of life, or pulmonary functions compared to standard exercise rehabilitation. Both groups showed improved HRV.
Wootton et al. (2019) found no difference in physical activity levels in COPD patients using pedometers for feedback compared to those without. Similarly, their 2018 study showed no differences in health-related quality-of-life measures.
Kaja et al. (2020) used a vibratory flutter device, enhanced with biofeedback, to reduce the accumulation of fluids and mucus in COPD patients. The biofeedback resulted in improved oxygen saturation, decreased dyspnea scores, and increased volume of removed secretions.
O’Dwyer et al. (2020) found that biofeedback improved inhaler-use compliance and respiratory symptoms in patients with breathing problems, including COPD.
Quasi-Experimental Designs
In a study by Giardano et al. (2004), 20 COPD patients underwent five HRVB sessions and 4 weeks of walking practice with pulse oximetry biofeedback. Ten weeks later, the patients demonstrated significant enhancements in the distance walked in 6 minutes, quality of life (as per the St. George's Respiratory Questionnaire), reduced breathlessness and disability, and improved heart rate variability during spontaneous breathing.
Clinical Efficacy
Gilbert (2023) rated biofeedback
for COPD as level 3 - probably efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
This rating was due to limitations in study design and sample size.
Approximately 18% of adults, which equates to slightly more than one out of every six individuals, report being in a state of depression or currently undergoing treatment for depression. This is a substantial increase of over 7 percentage points compared to the year 2015, when Gallup began to monitor this topic (Gallup, 2023).
Nearly 30% of adults report having received a clinical diagnosis of depression at some stage in their lives, a proportion that is at an all-time high according to the survey. The percentage of U.S. adults reporting a depression diagnosis at some point in their lifetime has climbed to 29.0%, almost 10 percentage points higher than the rate recorded in 2015. The proportion of Americans currently diagnosed or being treated for depression has also risen to 17.8%, an increase of roughly seven points over the same time frame.
More than a third of women (36.7%) report being diagnosed with depression at some point in their lifetime, which is significantly more than the 20.4% of men. Furthermore, the rate of diagnosis for women has increased at nearly twice the pace of that for men since 2017. Those aged between 18 to 29 (34.3%) and 30 to 44 (34.9%) have markedly higher lifetime rates of depression diagnosis than those over the age of 44.
Women, with a rate of 23.8%, and adults aged between 18 to 29, with a rate of 24.6%, exhibit the highest levels of current depression or are receiving treatment for depression. These two groups, along with adults aged 30 to 44, show the most rapid increase in rates compared to the figures from 2017, with a rise of 6.2 and 11.6 percentage points, respectively.
The rates of lifetime depression are also accelerating among Black and Hispanic adults, and have now overtaken those reported by White respondents. Historically, White adults have reported marginally higher rates of both lifetime and current depression.
Multiple pathways to depression include polygenic inheritance, dysfunction involving the lateral and medial orbitofrontal cortex and limbic
system, and environmental factors (McGrady & Moss, 2013).
Depression is associated with activation of the lateral orbitofrontal cortex, which signals that our behavior has not been rewarded. This activation may be related to feelings of loss and disappointment. Since this region communicates with networks responsible for our self-concept, this may also lower self-esteem (Cheng et al., 2016).
Depression also involves reduced activation of reward circuitry in the medial orbitofrontal cortex and its communication with autobiographical memory systems. These changes may contribute to depressed patients' lack of enjoyment of daily activities and difficulty remembering happy experiences.
EEG and functional MRI (fMRI) are the primary NF interventions, and EMG and HRV are the central biofeedback interventions for depression.
NF EEG protocols attempt to correct frontal alpha asymmetry or enhance parietal-occipital upper alpha. The rationale for alpha asymmetry neurofeedback for mood disorders is
that the left frontal cortex mediates approach behavior while the right
mediates negative affect.
Clinical depression is associated
with less activation of the left frontal lobe than the right. Since alpha
is an "idling frequency," this asymmetry is seen when alpha amplitude is
greater in the left (F3) than the right frontal
lobe (F4). The goal of alpha asymmetry
NF for depression is to correct this imbalance, decreasing
left frontal alpha with respect to right frontal alpha.
Successful NF training increases the activation of the left hemisphere with respect to the right.
Before EEG asymmetry training, patients are trained using diaphragmatic
breathing and autogenic phrases to teach them to relax and warm their
hands. The hand-warming criterion is 95 degrees F.
Patients are seen once or twice a week for one-hour sessions, which
consist of 30 minutes of EEG training followed by 30 minutes of
psychotherapy. Scalp sites F3 and F4 are used and are referenced to
CZ. A bell or
clarinet tone reinforces behavior when the asymmetry score exceeds
0 (right alpha amplitude exceeds left).
Typically, it is desirable for 15-18 Hz amplitude to be higher and 8-11 Hz amplitude to be lower at F3 compared to F4.
fMRI protocols attempt to up-regulate the activity of targeted regions that mediate positive emotion.
Neurofeedback and Biofeedback Studies
Neurofeedback (NF) studies for depression have implemented EEG and fMRI protocols aimed at adjusting brain activity patterns linked to mood disorders. Clinical depression often shows less activation in the left frontal cortex, associated with positive emotions, than the right, linked to negative emotions. This is seen in greater alpha amplitude (a frequency indicating idling) in the left frontal lobe. Alpha asymmetry NF aims to rectify this imbalance, decreasing left frontal alpha relative to right.
EEG Randomized Controlled Trials
Choi et al. (2011) conducted a pilot study on MDD patients, employing alpha asymmetry NF and a psychotherapy placebo. Only the NF group showed significant improvements on depression scales, with half of the participants improving on both Hamilton Depression Rating Scale (HAM-D) and Beck Depression Inventory (BDI-II).
Hashemian and Sadjadi (2015) performed an RCT on adolescents with MDD, comparing real NF to placebo NF treatment. Both groups showed reduced depression symptoms, with no significant difference between them, though the effect size was larger for the real NF group. Since the study involved adolescents who might show distinct neurochemistry and treatment responses, these results should be considered separate from adult studies. Also, the absence of detailed NF protocol information warrants careful interpretation of these results.
Functional MRI Randomized Controlled Trials
Real-time functional MRI NF (rtfMRI-nf) interventions are designed to increase the metabolism of brain regions, like the ventromedial prefrontal cortex, that mediate positive affect.
Young et al. (2014) assigned patients with major depressive disorder (MDD) to receive real-time fMRI neurofeedback (rtfMRI-NF) from the left amygdala or control region. The experimental group increased activation in the target area during positive memory recall and maintained this without neurofeedback, while the control group showed no increased activation. Depression scores decreased in both groups, but the experimental group also reduced anxiety scores and increased happiness ratings more significantly.
Young et al. (2017) conducted a double-blind, placebo-controlled RCT on MDD patients, targeting the amygdala or a control region. The experimental group showed increased amygdala response and a significant decrease in depression symptoms, with 32% meeting remission criteria. In contrast, the control group showed an 8% decrease in symptoms, with 6% achieving remission.
Mehler et al. (2018) conducted an RCT on moderate to severe MDD patients, targeting either the insula and lateral prefrontal regions or a control region. Both groups successfully upregulated target regions and showed significant symptom reduction, with no significant difference between them.
Jaeckle et al. (2019) conducted an RCT on MDD patients, combining self-guided psychological intervention with rtfMRI-NF targeting right superior anterior temporal lobe and subgenual cortex areas, or the psychological intervention alone. Both groups showed significant symptom reduction, but no significant difference between them. However, NF training seemed more beneficial for MDD patients without anxious distress.
Biofeedback Randomized Controlled Trials
Surface EMG Biofeedback
Durmus et al. (2005) studied 50 women with knee osteoarthritis, assigning them to either biofeedback -assisted isometric exercise or electrical stimulation. Both groups showed significant improvements in pain, physical function, anxiety, and depression scores.
Heart Rate Variability Biofeedback
HRVB is possibly efficacious for depression, and its effects may be mediated by the diaphragm's stimulation of vagal afferent nerves (Gevirtz, 2013). This hypothesis is supported by findings that vagal nerve stimulation in some studies improved intractable depression.
Zucker et al. (2009) conducted a controlled pilot study with 38 participants with PTSD and substance use disorder. Participants were assigned to either HRVB or progressive muscle relaxation. Both groups reduced PTSD symptoms significantly, but the HRVB group achieved lower depression scores and higher HRV.
Breach (2012) conducted a preliminary RCT to evaluate the efficacy of HRVB compared to a placebo treatment in individuals with MDD. Both groups showed considerable improvements in depressive symptoms, but there were no significant differences between the groups.
Patron et al. (2013) studied 26 individuals with MDD after cardiac surgery. Participants were assigned to either HRVB plus usual treatment or usual treatment alone. The HRVB plus usual treatment group showed superior outcomes in increasing respiratory sinus arrhythmia (RSA) and decreasing depression values.
Caldwell and Steffen (2018) conducted an RCT to examine the effectiveness of HRVB as an adjunct to psychotherapy in treating MDD in female college students. The HRVB plus psychotherapy group showed superior outcomes compared to the psychotherapy-only group, including greater decreases in depressive symptoms and greater improvements in HRV indices.
Clinical Efficacy
Meehan, Shaffer, and Zerr (2023) rated neurofeedback (alpha-asymmetry and fMRI protocols) and biofeedback (HRVB) for depressive disorders as level 5 - efficacious and specific based on 10 RCTs in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
BFB treatment included HRV increase. NFB interventions included alpha asymmetry reduction, alpha/theta increase, and real-time functional MRI (rtfMRI) to increase left or right ventromedial prefrontal cortex, insula, dorsolateral prefrontal cortex, medial temporal lobe, or orbitofrontal cortex activity.
Participants achieved decreased behavioral inhibition, depression symptoms and severity, and state and trait anxiety.
FIBROMYALGIA (FM)
Fibromyalgia (FM) is a chronic benign pain disorder that involves pain,
tenderness, and stiffness in the connective tissue of muscles, tendons, ligaments, and adjacent soft tissue.
The
American College of Rheumatology (ACR) adult criteria include widespread pain for at least 3 months on both
sides of the body and pain during gentle palpation on 11 of 18 tender points on the neck, shoulder, chest, back,
arm, hip, and knee sites.
McGrady and Moss (2013) conceptualize FM as a “pain amplification disorder” produced by the twin
mechanisms of allodynia and hyperalgesia (p. 187).
Allodynia means that
patients experience previously benign stimuli as painful. Hyperalgesia means
patients experience mildly painful stimuli as severely painful. While an initial injury that damages tissue may
sensitize the body through peripheral and central sensitization, in other cases, there may be no identifiable
precipitating event. Sequelae of negative emotion and sleep deprivation increase pain and impair cognitive
performance. The graphic below depicts back pain in fibromyalgia.
Demographics
The 2010 ACR fibromyalgia adult criteria are probably met by 7.7% of women and 4.9%
of men. The female-to-male ratio is probably 4:1 due to underestimating its prevalence in men. While fibromyalgia is mainly
seen in women 20-50 years, with average onset at 47.8 years, it is also
diagnosed in adolescents and the elderly. The peak prevalence in women occurs between 60-70 years. Fibromyalgia pain typically
persists for 78.7 months (Donaldson & Sella, 2003; Boomershine, 2015).
Pathomechanics
The etiology of fibromyalgia appears to involve a central
hypersensitivity to heat, cold, and electrical stimulation
(Desmeules et al., 2003). Fibromyalgia patients may have low levels of
serotonin, amino acids like tryptophan, and insulin-like growth factor
(IGF-1), and high levels of substance P and ACTH.
Tender points are associated with local tenderness. When compressed, they produce local pain but not the referred
pain associated with trigger points. Pressure on tender points may increase overall pain sensitivity. Fibromyalgia
is sometimes confused with Myofascial Pain Syndrome (MPS) because both syndromes involve muscle tenderness and
local pain during palpation.
The table below was adapted from Alvarez and Rockwell (2002).
Patients may present with both fibromyalgia and MPS and have both tender points and trigger points. Accurate
diagnosis requires careful examination by an experienced clinician (Alvarez & Rockwell, 2002).
Biofeedback and Neurofeedback Randomized Controlled Trials
Glombiewski et al. (2013) reviewed seven studies of biofeedback for fibromyalgia (FM), finding short-term pain reduction but not long-term, with little efficacy for fatigue, depression, or sleep.
Meeus et al. (2013) reviewed 16 controlled studies of HRV levels in FM and chronic fatigue syndrome (CFS), indicating that FM patients had higher sympathetic and lower parasympathetic activity.
Reneau et al. (2020) reviewed research on HRVB for FM, suggesting beneficial effects of HRV on chronic pain.
Babu et al. (2007) conducted a study on 30 FM patients, comparing SEMG biofeedback to sham biofeedback. Both groups showed symptom improvement, but the biofeedback group improved more.
Baumueller et al. (2017) studied SEMG biofeedback in a randomized controlled trial, focusing on the upper trapezius muscle. Although the treatment group showed improved trapezius pain thresholds, overall pain did not improve.
Wu et al. (2021) extended Kayiran's neurofeedback study, showing significant improvements in pain severity, pain interference, FM symptom severity, sleep latency, and sustained attention in the NFB group.
Research has included HRVB as a treatment component in
addition to exercise, cognitive therapies (Acceptance and Commitment Therapy and Cognitive Behavioral Therapy),
and interventions to improve sleep habits. The putative mechanism may be increased autonomic balance (Gevirtz,
2013).
Clinical Efficacy
Gilbert (2023) rated biofeedback and neurofeedback
for fibromyalgia at level 3 - probably efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
Increased sympathetic efferent signals to muscle spindles and overexertion can produce a spasm in the muscle spindle's intrafusal fibers, increasing muscle spindle capsule pressure and causing myofascial pain.
Demographics
In 2016, 50 million adults in the U.S. suffered from chronic pain, defined as pain persisting for three months or more, leading to significant healthcare expenses and a decrease in productivity.
About 14.4% of the United States population experiences chronic musculoskeletal pain. Almost everyone develops a
trigger point during their lives. About 21-93% of patients diagnosed with regional pain complaints present with myofascial pain. This syndrome is equally distributed between men and women. Trigger points can be found in patients of all ages, including infants. Sedentary individuals have a higher risk of developing trigger points than individuals who daily engage in vigorous activity (Finley, 2013).
Pathomechanics
Hubbard and Gevirtz proposed that sympathetically-mediated
muscle spindle spasm
may be the essential
local mechanism in myofascial pain.
Gevirtz (2013) hypothesizes that HRVB improvement
in autonomic balance may interfere with SNS innervation of trigger points through the mechanism of accentuated
antagonism (Olshansky, Sabbah, Hauptman, & Colucci, 2008).
Chronic neck pain, a common complaint in clinical practice, is a multifactorial condition with several potential underlying causes. It's critical for physicians to be aware of these possible causes to accurately diagnose and effectively treat the condition.
Mechanical or Musculoskeletal Factors: One of the most common causes of chronic neck pain is mechanical or musculoskeletal issues, including cervical spondylosis (age-related wear and tear affecting the spinal disks in the neck) and cervical degenerative disc disease (DDD). Poor posture, especially related to workplace ergonomics or prolonged use of digital devices (known as "text neck"), can also lead to chronic neck pain (Neupane et al., 2017).
Trauma or Injury: Accidents or injuries, such as whiplash injuries from motor vehicle accidents, can lead to chronic neck pain. In whiplash, the soft tissues in the neck can be strained or torn (Spitzer et al., 1995).
Psychological Factors: Psychological factors, including stress, anxiety, and depression, have been associated with chronic neck pain. Studies have suggested that these factors can contribute to both the onset and the persistence of neck pain (Shahidi et al., 2017).
Myofascial Pain Syndrome: This chronic condition involves pain stemming from trigger points in the muscles, often in the neck and shoulder region. The pain can be persistent and may even radiate to other areas (Alonso-Blanco et al., 2011).
Neuropathic Pain: Certain conditions, such as cervical radiculopathy, can lead to nerve root compression and consequently cause neuropathic pain in the neck. This type of pain is often described as burning or sharp, and may be associated with other neurological symptoms, such as tingling or weakness.
Systemic Diseases: Certain systemic diseases, such as rheumatoid arthritis and ankylosing spondylitis, can cause neck pain. Infections, tumors, and certain metabolic diseases can also lead to neck pain (Binder, 2007).
Chronic Neck Pain Randomized Controlled Trial
Hallman et al. (2011) conducted a study examining the impact of HRVB training on chronic neck pain in stressed patients. The results showed that the group that received HRVB training reported significant improvements in pain, vitality, and social functioning compared to the no-treatment control group.
Clinical Efficacy
Based on five RCTs, Rosenthal (2023) rated biofeedback
for chronic neck pain as level 4 - efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
CARDIOVASCULAR DISORDERS
CORONARY ARTERY DISEASE
HRVB shows promise in coronary artery disease (CAD).
Coronary artery disease (CAD) is characterized by reduced coronary artery
circulation. Check out an informative YouTube video Atherosclerosis by Nucleus Medical Media.
Demographics
Approximately 18.2 million adults over the age of 20 in the United States have CAD, which equates to about 6.7% of the adult population (Virani et al., 2020). CAD was the leading cause of death, accounting for 365,914 deaths in the US in 2017, or about 1 in every 7 deaths (Virani et al., 2020).
Coronary artery disease (CAD) prevalence and incidence are influenced by several demographic factors. The disease incidence rises with age in both genders, but men tend to be affected at a younger age, while women see a surge post-menopause (Mozaffarian et al., 2016). Racial and ethnic disparities are observed, with CAD being more common among South Asians and African Americans due to a higher burden of risk factors (Volgman et al., 2018). Socioeconomic status also affects CAD incidence, with those in lower socioeconomic brackets having a higher incidence due to increased exposure to cardiovascular risk factors (Kaplan and Keil, 1993). Geographically, CAD is more prevalent in developed countries, but is rising in developing nations due to lifestyle changes and increased life expectancy (Yusuf et al., 2001).
Graphics courtesy of HeartWare International Inc, Framingham, MA, and Africa Studio/ Shutterstock.com.
Pathomechanics
Coronary artery disease (CAD) is a complex process that involves various pathophysiological mechanisms, including endothelial dysfunction, lipid infiltration and inflammation, and plaque formation and rupture, leading to myocardial ischemia and potentially infarction.
Endothelial Dysfunction: The inner lining of the coronary arteries, the endothelium, normally maintains a balance between vasodilators and vasoconstrictors, prevents thrombosis, and inhibits smooth muscle proliferation and inflammation. However, in CAD, these functions are compromised. Endothelial dysfunction is often triggered by risk factors such as hypertension, hyperlipidemia, diabetes, smoking, and a sedentary lifestyle (Esper et al., 2006).
Lipid Infiltration and Inflammation: The compromised endothelium allows for the infiltration of low-density lipoprotein (LDL) cholesterol into the arterial wall. The LDL particles undergo oxidation and form oxidized LDL (oxLDL), which is a potent pro-inflammatory stimulus. This triggers the recruitment of monocytes and T lymphocytes to the site, and the monocytes differentiate into macrophages, which engulf the oxLDL to form "foam cells." The accumulation of these cells forms the fatty streak, which is the initial lesion in CAD (Ross, 1993).
Plaque Formation and Rupture: Over time, smooth muscle cells migrate over the fatty streak and form a fibrous cap, transforming the lesion into a stable atherosclerotic plaque. However, under the influence of various factors such as inflammation, the cap can weaken and rupture, exposing the thrombogenic core to the blood and leading to clot formation. If the clot occludes the artery, it can cause myocardial ischemia and infarction (Naghavi et al., 2003).
The pathomechanics of CAD is a dynamic process influenced by various genetic and environmental factors. Therapeutic strategies focus on addressing these risk factors and the underlying mechanisms to prevent plaque formation and rupture.
Randomized Controlled Trials
There is
increasing evidence that HRVB may improve cardiac function by restoring autonomic balance (Gevirtz, 2013). This
represents a paradigm shift from the earlier model of reducing SNS activation (Moravec & McKee, 2013).
Several studies have demonstrated the promise of HRVB in treating congestive heart failure and coronary
artery disease.
Cowan et al. (2001) conducted a RCT with 133 cardiac arrest survivors, 80% of whom had CAD. They found that psychosocial therapy including HRV-BF and CBT significantly decreased the risk of cardiovascular death by 86% at 2 years.
Del Pozo et al. (2004) explored the effectiveness of cardiorespiratory biofeedback in increasing HRV in patients with coronary artery disease (CAD). They randomized 63 CAD patients into either traditional cardiac rehabilitation or a biofeedback group that underwent six sessions of abdominal breathing training, HRV enhancement biofeedback, and daily 20-minute breathing exercises. While the biofeedback group saw an increase in HRV from baseline to weeks 6 and 18, the control group's HRV deteriorated.
Nolan et al. (2005) studied 46 CAD patients and found that HRV-BF training improved their HRV response to stress challenges. However, resting HRV did not change, potentially due to the small sample size.
Swanson et al. (2009) conducted a study with 29 heart failure patients, who were randomly assigned to an experimental group receiving six weekly sessions of respiratory training, HRVB, and daily practice, or a comparison group receiving sham alpha-theta biofeedback and daily practice. The experimental group showed increased exercise tolerance from baseline to follow-up.
Climov et al. (2014) studied 31 CAD patients undergoing cardiac coherence BF during cardiac rehabilitation (CR). They found no significant changes in blood pressure, HRV, anxiety, depression, or Type D personality traits. However, cardiac coherence significantly improved in most of the intervention group.
Lin et al. (2015) involved 154 CAD patients and found that HRV-BF increased HRV and reduced hostility. Both the intervention and control group experienced a decrease in blood pressure. The authors also suggested that HRV-BF could improve baroreflex sensitivity in CAD patients.
Yu et al. (2018) conducted a study with 222 CAD patients and found that HRV-BF significantly reduced respiration rate, depression, and hostility, and increased HRV. It also led to decreased hospital admissions and ER visits at a 1-year follow-up. Effects on cardiac hospitalizations and ER visits were not statistically significant. No deaths were observed in either group during the study or the 1-year follow-up period.
Clinical Efficacy
Moravec (2023)
rated biofeedback for coronary artery disease as level 3 -
probably efficacious in Evidence-Based Practice in Biofeedback and Neurofeedback (4th ed.).
ESSENTIAL HYPERTENSION
Blood Pressure Mechanics
Blood pressure (BP) is the product of
cardiac output (amount of blood
pumped by the heart) and systemic vacular resistance.
Cardiac output is the product of
stroke volume (amount of blood ejected with each beat) and
stroke rate (number of beats per minute).
Systemic vascular
resistance. Systemic vascular resistance represents all systemic blood vessels' total resistance and is influenced by blood viscosity (thickness) and blood vessel length and radius.
Arterioles (small arteries) play a
significant role in controlling systemic vascular resistance. A minor
adjustment in arteriole diameter can significantly change systemic
vascular resistance and, consequently, BP and tissue
perfusion (Tortora & Derrickson, 2021).
Stage 1 hypertension (elevated BP) is defined when systolic BP (SBP) is 130 mmHg or higher and/or diastolic BP (DBP) is > 80 mmHg or higher.
The 2017 American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines (Whelton et al., 2017) are shown below.
The 2017 guidelines classify 103 million Americans as hypertensive instead of 72 million under the 2003 National Heart, Lung, and Blood Institute (NHLBI) guidelines. Under the 2017 guidelines, 50% of men and 38% of women are hypertensive.
The NIH Systolic Blood Pressure Intervention Trial (SPRINT) treatment of high-risk hypertensive patients 50 years or older with a SBP of 120 mmHg reduced cardiovascular events by 30% and all-cause mortality by almost 25%, compared to a target of 140 mmHg (Medscape, 2015).
McEvoy and colleagues (2016)
warned that medical treatment to reduce SBP below 140 mmHg should not allow DBP to fall below 70 mmHg, particularly below 60 mmHg, because this could threaten the delivery of blood to the heart. Low DBP values were independently associated with progressive heart damage, coronary heart disease, and death.
Demographics
One-third of Americans and two-thirds over 60 are hypertensive (Benjamin et al., 2018). African Americans and patients diagnosed with diabetes have a higher prevalence of hypertension. Patients with elevated BP may progress to hypertension without lifestyle and drug intervention (Huether et al., 2020).
Hypertension Symptoms
While elevated BP can be "silent," diverse symptoms like blurred vision and swelling ankles (edema) may accompany this chronic health condition.
Researchers have reported that slight blood pressure elevations in middle age are associated with a 30% greater risk of dementia or cognitive impairment in two decades. Medication that lowers BP can reduce this risk (Hughes et al., 2020).
Pathomechanics
Essential hypertension, also known as primary hypertension, is a condition where there is a persistent elevation of systemic arterial blood pressure without an identifiable cause. The pathomechanics of essential hypertension are complex and not entirely understood. Still, they likely involve a combination of genetic factors, environmental factors, and various physiological systems, including the renal system, nervous system, and vascular function.
Genetic Factors: There is a strong genetic component to essential hypertension, with studies indicating that 30-50% of blood pressure variability can be attributed to genetic influences (Padmanabhan et al., 2012).
Renal Function: The kidneys play a crucial role in blood pressure regulation through the renin-angiotensin-aldosterone system (RAAS). Any disturbance in this system can lead to sodium and fluid retention, resulting in increased blood volume and, consequently, hypertension (Hall & Hall, 2021).
Autonomic Nervous System: Overactivity of the sympathetic nervous system can result in increased heart rate, vasoconstriction, and increased renin release, all of which can contribute to elevated blood pressure (Mancia et al., 2019).
Vascular Function: Changes in the structure and function of the blood vessels, including increased vascular resistance and stiffness, can also contribute to the development of hypertension (Harvey et al., 2015).
Environmental Factors: Factors such as high salt diet, alcohol consumption, obesity, physical inactivity, and stress can lead to the development of essential hypertension.
Autonomic imbalance, involving sympathetic overactivity and parasympathetic
underactivity, plays a vital role in developing essential hypertension. Demographic factors (age,
gender, and ethnicity) and psychological factors (depression, anger, and anxiety) influence BP
(McGrady & Moss, 2013).
Check out an informative YouTube video High Blood Pressure by Nucleus Medical Media.
Based on twin studies and the Framingham Heart Study, the heritable component of BP ranges from 33-57% (Madhur, 2014).
Measuring Blood Pressure
Goedde, Kabins, and Koenig (2007) explored the effects of
patient speech on BP in a study that involved 55 undergraduates (28 men and 27 women). SBP was 11.4 mmHg lower, and DBP was 11.6 mmHg lower during silence than speech. These findings suggested that patient conversation while taking BP could elevate their readings.
The infographic below, adapted from Elizaveta Galkina in the December 16, 2024 the Wall Street Journal article, "Your Blood Pressure Reading Is Probably Wrong," summarizes mistakes that can elevate blood pressure measurements.
Do not ingest caffeine within 30 minutes of measurement.
Recommended Lifestyle Changes
Potential SBP reductions for hypertensive patients will vary by individual. Weight loss is the most effective lifestyle change due to the multiple pathways by which obesity can increase BP. About 60% of hypertensive patients and 25% of normotensive individuals are salt-sensitive. From 4-5% of individuals experience lower BP when they ingest salt (Harvard Heart Letter, August 2019). Stress management can make valuable contributions to BP control.
The main drugs used to treat hypertension include diuretics, ACE
inhibitors, beta-blockers, and calcium channel blockers.
Diuretics reduce blood volume by
removing water and salt in urine.
ACE inhibitors block angiotensin II
formation, resulting in vasodilation (reducing systemic vascular
resistance) and reduced aldosterone secretion.
Beta-blockers inhibit renin secretion and decrease heart rate
and cardiac contractibility. Finally, calcium
channel blockers slow Ca2+ entry into myocardial fibers,
reducing the heart's workload and contraction force.
Biofeedback
interventions can interact with anti-hypertensive medication resulting
in significant BP reductions. Patients should monitor their
BP daily and discuss medication adjustments with
their physician before making changes on their own.
A Pathways Model Intervention
Click the Read More button for an example of a Pathways Model hypertension intervention.
Richard was a 45-year-old mildly overweight Caucasian male with a 10-year history of stage 1 hypertension. While his BP was well controlled using a combination of an ACE inhibitor and beta-blocker, he wanted to reduce his reliance on medication. His Level One interventions were to (1) track his daily steps and gradually increase them to 10,000 steps per day, (2) record his alcohol and food intake and weigh himself weekly, (3) log his BP every morning after he woke up, and (4) take a large movement break every hour.
He initiated his Level Two interventions 1 month later since his BP had not yet significantly decreased. These steps included (1) recruiting an exercise partner for 35-minute walks at least five times a week and (2) practicing slow, abdominal breathing using an Institute of HeartMath Inner Balance HRVB training system. At this time, he added a new Level One intervention, which was listening to classical music at home for at least 30 minutes per day.
After 2 months, his blood pressure had gradually declined, but he had made no progress in reducing his weight. He added a new Level One intervention of using an activity tracker to measure and log his sleep and to adjust his work schedule to ensure 8 hours of sleep each night. His single Level Three intervention was to consult twice with a licensed dietician to assess and modify his diet. Dietary counseling guided him to reduce saturated fats and simple carbohydrates by adopting a Mediterranean diet.
At the end of 6 months, Richard's diet, sleep, and energy had significantly improved. His physician encouraged him to eliminate the beta-blocker and halve the dosage of his ACE inhibitor while continuing daily charting of his blood pressure. His BPs declined to the normotensive range, his blood lipids were normal, and he lost 15 pounds. At 1-year follow-up, his BPs remained well controlled on reduced medication. He continued his Mediterranean diet but regained half the weight he had lost, and his sleep continued to be excellent.
Richard's case history shows that the success of biofeedback can depend on the foundation provided by Level One and Level Two interventions. Richard's self-monitoring of his BP, diet, physical activity, sleep, and weight, and self-directed HRVB practice, helped him develop mindfulness. His recruitment of an exercise partner leveraged the power of a social network to motivate him to exercise. He ensured his safety by partnering with his physician to reduce his medication gradually and logging his progress. Finally, while he should celebrate his success in losing weight, he might consider getting back on the "path" to more consistent weight control.
McGrady's (1996) Analysis of Efficacy Studies with the Best Outcomes
McGrady (1996) identified six factors
in efficacy studies reporting the largest and most consistent BP reductions.
Prediction Models of Clinical Response to Biofeedback
McGrady and Higgins (1989) and Weaver and McGrady (1995) studied
unmedicated white adult males with mild to moderate hypertension. These
patients received SEMG and temperature biofeedback, autogenic training,
home practice, and BP monitoring.
The most responsive patients showed a high heart rate, cool hands, high
SEMG, and elevated plasma renin activity. The best predictors of how much
BP decreased were high heart rate, cool hands, high anxiety,
and high-normal cortisol.
A multi-modal strategy that combines biofeedback, relaxation training, and medical management may be most effective for patients whose BP reacts to stressors (Frank et al., 2010).
Blood Pressure Reduction Mechanisms
Linden and McGrady (2016) propose several mechanisms for the BP-lowering effects of biofeedback. Direct BP feedback isn't typically as effective as other types, but Tsai et al. (2007) found it significantly advantageous over sham biofeedback when baseline BP was controlled.
Thermal biofeedback may work by dilating peripheral blood vessels, indicating sympathetic adrenergic activity, thereby decreasing total peripheral resistance. Given the reduced baroreceptor sensitivity in hypertension, enhancing baroreceptor response via baroreceptor feedback or respiratory training could reduce BP (Overhaus et al., 2003; Reyes del Paso et al., 2006).
Trials of HRVB, compared to slow breathing or relaxation alone, produced significant BP decreases and correlated HRV increases (Nolan et al., 2010).
Gevirtz (2005) proposed that resonance frequency biofeedback may lower BP
by stimulating the baroreflex.
Designing a Treatment Program for Your Client
As reviewed earlier, McGrady's (1996) six factors for successful hypertension interventions should be the foundation of any treatment program. Essential hypertension treatment should be tailored to your client based on detailed medical and behavioral
assessments. Biofeedback for hypertension should not be attempted without
a recent medical workup and continuing communication with your patient's
physician. Medical oversight can be critical throughout treatment and
significantly when medication requirements change.
Following the medical evaluation, a biofeedback practitioner should evaluate a
patient diagnosed with essential hypertension with a psychophysiological
profile to identify which response systems require training. A multi-modal strategy that retrains
dysregulated systems, promotes relevant lifestyle changes, and teaches stress management when needed shows the most clinical
promise.
Randomized Controlled Trials
Lehrer and colleagues (2020) reported nonsignificant effects for diastolic and systolic blood pressure in their meta-analysis of HRVB applications.
Costa Vital et al. (2021) conducted a meta-analysis of nine studies examining biofeedback as a treatment for essential hypertension, involving 462 participants. The analysis revealed that biofeedback significantly improved blood pressure control, especially DBP levels. Various biofeedback types, including galvanic skin response, HRV, and surface electromyography (SEMG), were used, but the type was not a crucial factor for success in reducing blood pressure. All modalities had a psychophysiological basis, such as HRVB linked with significant blood pressure reductions and improved baroreflex functioning in hypertensive patients.
Lin et al. (2012) found that HRVB significantly reduced blood pressure and increased HRV and baroreflex sensitivity in 43 prehypertensive young adults, with effects persisting at the 3-month follow-up. Slow breathing had similar but nonsignificant effects.
Xu et al. (2007) demonstrated that SEMG biofeedback with relaxation training significantly decreased systolic and diastolic blood pressure and increased HRV in 49 college students with prehypertension. The improvements persisted at the 3-month follow-up.
Wang et al. (2010) showed that combining SEMG biofeedback with slow abdominal breath training in post-menopausal women with prehypertension led to more significant decreases in SBP and DBP than biofeedback alone. However, there was no significant impact on HRV post-treatment or at follow-up.
Wang et al. (2016) found no significant difference between real feedback and sham feedback in reducing SBP in individuals with prehypertension or stage I hypertension. The training did not impact anxiety scores.
Chen et al. (2016) found that HRVB significantly improved SBP, DBP, and cardiac autonomic activity in college students with prehypertension compared to slow abdominal breathing and no treatment. The HRV group showed improvements at the 3-month follow-up.
Yau and Loke (2021) found that diaphragmatic breathing significantly decreased SBP, DBP, and anxiety in hypertensive and prehypertensive individuals.
Nakao et al. (2000) found that biofeedback significantly reduced SBP and DBP in white-coat hypertensives and essential hypertensives. The training moderated the stress response more for the white-coat hypertensives than for the essential hypertensives.
Clinical Efficacy
Based on three RCTs for essential hypertension and five for pre-hypertension treatments, McGrady (2023)
rated biofeedback for essential hypertension as level 4 -
efficacious in Evidence-Based Practice in Biofeedback and Neurofeedback (4th ed.).
The biofeedback interventions trained participants to lower electrodermal and SEMG activity, and SBP, and increase HRV.
Participants lowered DBP and SBP, and increased baroreflex sensitivity (BRS). BRS would be high if the baroreflex system reacts strongly to a small BP change. If it reacts weakly, BRS would be low.
Preeclampsia affects 6-8% of pregnancies and is a leading cause of perinatal morbidity and
mortality (Lim, 2014; Walling, 2004).
Pathomechanics
Preeclampsia is a complex, multi-system disorder unique to human pregnancy, characterized by the onset of hypertension and proteinuria after the 20th week of gestation. Its pathogenesis involves multiple interconnected pathways, including abnormal placentation, immune maladaptation, oxidative stress, and endothelial dysfunction.
Abnormal Placentation: It is hypothesized that preeclampsia begins with abnormal placentation (Roberts & Escudero, 2012).
Immune Maladaptation: Preeclampsia is also thought to involve an abnormal maternal immune response to the fetus (Saito et al., 2007).
Oxidative Stress: Poor placental perfusion due to abnormal placentation results in intermittent hypoxia-reoxygenation injury, leading to oxidative stress (Redman & Sargent, 2005).
Endothelial Dysfunction: The anti-angiogenic factors released by the placenta antagonize vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), leading to widespread endothelial dysfunction. This results in vasoconstriction, hypertension, proteinuria, and the other systemic manifestations of preeclampsia (Maynard et al., 2003).
In summary, the pathophysiology of preeclampsia is multifactorial, involving abnormal placentation, immune maladaptation, oxidative stress, and endothelial dysfunction. However, the precise mechanisms are still not fully understood, and further research is needed.
Randomized Controlled Trials
Little et al. (1984) conducted a randomized control trial (RCT) on 50 women with pregnancy-induced hypertension (PIH), comparing the efficacy of relaxation training, biofeedback-assisted relaxation (BART), and treatment as usual (TAU). The study found that both experimental groups outperformed the control group in hospitalization frequency, mean hospitalization length, diastolic blood pressure (DBP), and proteinuria. The relaxation-only group also achieved lower systolic blood pressure (SBP) than the control group. However, the study didn't confirm if the BART group learned to lower skin conductance (SC), which could explain the similar performance of the two treatment groups.
Somers et al. (1989) conducted an RCT on 45 women with mild PIH, assigning them to bed rest alone, compliance enhancement training, or biobehavioral intervention. The biobehavioral group showed increased hand temperature and reduced mean arterial pressure (MAP) compared to their baseline and other groups. Only 9 of 15 participants in this group had blood pressure measurements exceeding 95 mm Hg at the final prenatal visit, compared with 14 of 15 in the other groups. This suggests that a 4-hour biobehavioral intervention may be beneficial for mild PIH.
El-Kosery, Abd-El Raoof, and Farouk (2005) conducted an RCT on 35 women with preeclampsia, assigned to either a relaxation or control group. The relaxation group, which received GSR BART and antihypertensive drug methyldopa, showed a reduction in heart rate, SBP, DBP, proteinuria, and methyldopa dosage. The control group, which only received methyldopa, also showed reductions but had increased methyldopa dosage. At the end of the 6 weeks, the relaxation group showed greater reductions in SBP, methyldopa dosage, DBP, heart rate, and proteinuria than the control group. The study thus provided strong evidence for the effectiveness of GSR BART in managing PIH.
Clinical Efficacy
Based on three RCTs, Shaffer (2023) rated biofeedback
for preeclampsia as level 5 - efficacious and specific in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
Participants improved in hospitalization frequency and length,
diastolic blood pressure (DBP), mean arterial pressure (MAP), systolic blood pressure (SBP), methyldopa dosage, and proteinuria.
Anxiety, Phobia, and Post-Traumatic Stress Disorder
Generalized anxiety disorder (GAD) is defined by excessive anxiety and
worry most of the time for at least 6 months (Beidel, Bulik, & Stanley, 2014). Chronic overarousal
results in fatigue and insomnia, worsened by changes in their circadian rhythm due to their job or
travel (McGrady & Moss, 2013).
Patients perceive their worrying as outside their control. They present with physical (muscle tension) and
cognitive symptoms (the belief that worrying can prevent an adverse event). They are usually diagnosed with a second
disorder (Beidel, Bulik, & Stanley, 2014).
Specific phobia involves significant emotional distress, excessive anxiety,
or fear about an object or situation that disrupts everyday performance. DSM-5 lists five specifiers: animal
phobias, natural environment phobias, blood/injection/ injury phobias, situational phobias, and other phobias
(Beidel, Bulik, & Stanley, 2014).
Estimated lifetime prevalence rates for anxiety disorders in the United States are panic disorder (2.3-2.7%),
generalized anxiety disorder (4.1-6.6%), OCD (2.3-2.6%), PTSD (1-9.3%), and social phobia (2.6-13.3%). The
male-to-female ratio for a lifetime anxiety disorder is 3 to 2 (Yates, 2014).
Pathomechanics
Generalized Anxiety Disorder (GAD) is a chronic condition characterized by excessive, long-lasting anxiety and worries about nonspecific life events, objects, and situations. The pathomechanics of GAD involve a complex interplay of multiple factors, including neurobiology, genetics, environmental influences, and cognitive processes.
Neurobiology: GAD is linked to abnormal functioning within several brain structures, including the amygdala, prefrontal cortex, and anterior cingulate cortex. These areas play critical roles in fear response, emotion regulation, and cognitive processing of uncertainty and worry. Neurotransmitter systems, particularly the serotonin, norepinephrine, and GABA systems, are also implicated in the pathophysiology of GAD (Bandelow & Michaelis, 2015).
Genetics: Family and twin studies suggest a moderate genetic contribution to GAD, with heritability estimates ranging from 15% to 50%. However, the specific genes contributing to this disorder remain largely unknown (Hettema, 2008).
Environmental influences: Environmental stressors, particularly traumatic or stressful events in childhood, can increase the risk of developing GAD. This might be due to the impact of chronic stress on the brain's stress response systems, including the hypothalamic-pituitary-adrenal (HPA) axis.
Cognitive processes: Cognitive theories suggest that individuals with GAD have a heightened sensitivity to uncertainty and a propensity to perceive ambiguous situations as threatening. This cognitive bias may result in persistent worry and fear, key symptoms of GAD (Dugas, Gagnon, Ladouceur, & Freeston, 1998).
Overview
Most controlled, randomized experiments have found that
neurofeedback and biofeedback (electrodermal, SEMG, and temperature)
produce comparable anxiety reductions to relaxation procedures like
meditation and progressive relaxation. Biofeedback and relaxation
procedures may achieve equivalent results because anxiety involves
disordered attention and cognition in addition to abnormal physiological
arousal. In some cases, biofeedback may be superior to relaxation procedures and produce additive effects
when combined with medication.
Randomized Controlled Trials
Generalized Anxiety Disorder
Murphy (2009) conducted a study on 79 adults diagnosed with Generalized Anxiety Disorder (GAD) and randomly assigned 40 of them to undergo either Cognitive Behavioral Therapy (CBT) with heart rate variability training or CBT with Progressive Muscle Relaxation (PMR). Pre- and post-intervention assessments were conducted using several questionnaires and physiological measures, including heart rate, HRV, temperature, and skin conductance level. The HRV training involved home practice using a personal HRV training device, the StressEraser. Both groups showed significant reductions in anxiety, with the percentage of participants meeting GAD diagnostic criteria decreasing from 100% to 42% post-intervention. There were no significant differences between the HRV and PMR groups.
Anxiety As a Life Problem
This category includes anxiety in students, the workplace, gifted children, about medical interventions, and sport and the performing arts.
Henriques et al. (2011) conducted two studies using HRVB in college students and found significant reductions in anxiety and depression symptoms, though changes were not strongly related to HRV magnitude.
In the Ratanasiripong et al. (2012) study, 30 undergraduates assigned to a counseling plus HRVB group showed significantly larger improvements in anxiety scores than the counseling-only group.
Aritzeta et al. (2017) found that students who underwent biofeedback intervention significantly reduced anxiety and improved exam performance, in addition to increased HRV.
Lastly, Prinsloo and colleagues (2013) found that a single 10-minute HRV training session in adult males with work-related stress resulted in increased relaxation and a significant reduction in state anxiety, with a larger effect size than a control group using sham feedback. The control group, however, also showed reduced state anxiety, suggesting that focused attention might have relaxation benefits.
Clinical Efficacy
Based on 5 and 15 RCTs, respectively, Moss and Watkins (2023) rated biofeedback
for Generalized Anxiety Disorder and Anxiety as a Life Problem as level 4 - efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
The BFB interventions included HR decrease, HRV increase, SCL decrease, SEMG decrease, and virtual reality (VRB). The NF interventions included alpha increase and alpha/theta increase. Participants decreased HR, SCL, state and trait anxiety, and HR reactivity to stress.
They increased HRV measures (HF and LF power) and theta power.
Intermittent FAP is termed recurrent abdominal pain (RAP) and is seen in up to 10% of children
and 2% of adults, primarily women. Most of these patients were undiagnosed after a previous assessment (Greenberger, 2013).
Pathomechanics
Functional abdominal pain (FAP) is part of a group of disorders called functional gastrointestinal disorders (FGIDs). These disorders are classified by a group of symptoms focused around a disturbance in the functioning of the gastrointestinal system, without any structural abnormalities identifiable by routine diagnostic tests.
Various factors, including psychological stress, anxiety, and depression, can influence pain perception and amplification. These factors can lead to changes in gut motility, increased gut sensitivity, and altered pain perception. In FAP, there may be an increased sensitivity to normal gut sensations, often called visceral hypersensitivity. This heightened sensitivity can result in pain perception even with normal digestive functions (Korterink, Diederen, Benninga, & Tabbers, 2015).
Pain perception and amplification can be influenced by various factors, including psychological stress, anxiety, and depression. These factors can lead to changes in gut motility, increased gut sensitivity, and altered pain perception. In FAP, there may be an increased sensitivity to normal gut sensations, which is often referred to as visceral hypersensitivity. This heightened sensitivity can result in pain perception even with normal digestive functions (Korterink, Diederen, Benninga, & Tabbers, 2015).
In addition, there is evidence of altered gut microbiota in patients with FAP. Changes in the gut microbiota can affect gut barrier function, immune function, and gut-brain signaling, which could potentially contribute to the development of FAP (Saps, van Tilburg, Lavigne, Miranda, Benninga, Taminiau, & Di Lorenzo, 2016).
The pathophysiology of FAP is complex and multifactorial, involving altered gut-brain communication, increased pain sensitivity, psychological factors, and possible changes in gut microbiota.
Randomized Controlled Studies
Heart rate variability biofeedback (HRVB) and thermal biofeedback have been used to treat FAP. These interventions may theoretically restore autonomic balance and correct central processes that amplify visceral pain.
Humphreys and Gevirtz (2000)
conducted a RCT of 64 children and adolescents that compared HRVB with cognitive-behavioral therapy and family therapy. HRVB produced the best outcomes.
Sowder et al. (2010) compared HRVB with a control group. Improved symptom ratings were correlated with changes in the LF/HF ratio used to measure vagal tone.
Uncontrolled Study
In this uncontrolled study, Guiles, Stern, and Gevirtz (2014) reported complete remission in 64% of 11 pediatric patients diagnosed with recurrent abdominal pain after 10 sessions of HRVB.
Clinical Efficacy
Guiles, Stern, Huntley, and Gevirtz (2016) rated biofeedback
for FAP as level 2 - possibly efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (3rd ed.). They awarded this rating due to limitations in experimental design and sample size.
IBS has an estimated prevalence of 10-20% and 1-2% incidence in the United States. About 10-20% of persons with IBS receive medical treatment for this disorder. In Western nations, women develop IBS two to three times more often than men. About 50% of IBS patients report the onset of symptoms before age 35 (Lehrer, 2014).
Pathomechanics
Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by recurrent abdominal pain associated with alterations in bowel habits. IBS can significantly impact a patient's quality of life and is often challenging to manage due to its multifactorial pathogenesis.
Brain-Gut Axis Dysfunction: The bidirectional communication between the gut and brain, known as the brain-gut axis, is thought to be dysregulated in IBS. This dysregulation can affect gut motility, visceral sensitivity, and mucosal function, leading to IBS symptoms. Psychological stress can also affect the brain-gut axis and may exacerbate IBS symptoms (Mayer, 2011).
Visceral Hypersensitivity: Patients with IBS often exhibit an increased sensitivity to pain and other sensations in the gut, a phenomenon known as visceral hypersensitivity. This can lead to the perception of pain even during normal digestive processes (Camilleri, 2012).
Altered Gut Motility: Some patients with IBS may experience altered gut motility, leading to symptoms such as constipation (IBS-C) or diarrhea (IBS-D). The exact cause of this altered motility is not entirely understood. Still, it may be related to factors such as dysregulation of the enteric nervous system or imbalances in serotonin (a neurotransmitter involved in gut motility) (Saha, 2014).
Microbiota Changes: Growing evidence suggests an altered gut microbiota in IBS patients. Changes in the composition of the gut bacteria may contribute to IBS symptoms through various mechanisms, including increased gut permeability, immune activation, and production of gas and other metabolites (Simrén, Barbara, Flint, Spiegel, Spiller, Vanner, ... & Zoetendal, 2013).
Post-Infectious IBS: A subset of IBS patients develop symptoms following an episode of acute gastroenteritis, a condition called post-infectious IBS. This suggests that immune activation and low-grade inflammation may play a role in IBS pathogenesis (Spiller & Garsed, 2009).
Randomized Controlled Trials
In two separate studies, biofeedback-based heart rate variability (HRV) training was used as a non-pharmacological intervention for Irritable Bowel Syndrome (IBS) and compared to other treatment modalities.
In Thompson's study (2010), 37 adults with IBS were recruited and randomly assigned to either HRVB training or cognitive therapy. Despite low compliance with home practice in both groups, participants in both conditions showed improvements on all measures, except for the Pittsburgh Sleep Quality Index, with no significant differences between groups. Thus, HRV training was found to be equivalent to cognitive therapy, suggesting that it could be an effective alternative treatment for IBS.
In the Dobbin et al. study (2013), 128 adults with refractory IBS were randomly assigned to either HRVB or hypnosis-based treatment, with 61 completing treatment. Again, both groups showed significant reductions in IBS symptoms and anxiety and depression, with no significant differences between the HRV and hypnosis groups.
Clinical Efficacy
Based on five RCTs, Moss and Watkins (2023) rated rectosigmoid and temperature biofeedback with Progressive Relaxation
for IBS as level 4 - efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
OPTIMAL PERFORMANCE APPLICATIONS
Major HRV performance applications include anxiety, depression, and over-arousal. Lehrer and colleagues' (2020) systematic review found that HRVB produced the largest effect sizes for athletic performance.
Indicators for Using Paced Breathing and/or RSMT Protocols
Paced breathing is a good place to start since most software allows users to select breath pacers. Adults often start with 6.0 breathing rates. This means one full inhalation and exhalation cycle every 10 seconds or six breath cycles per minute. Typically, the exhalation is a second longer than the inhalation. Although there are several variations, a 4-second inhalation followed by a brief pause and a 5-second exhalation permits a 10-second breath cycle.
Athletes need to be aware of diaphragmatic muscle use while minimizing the recruitment of upper chest muscles. Some call this abdominal or belly breathing. Athletes should expect that greater use of new muscles like the diaphragm may cause them to fatigue. They should anticipate feeling light-headed and take a break to reverse this. They should be prepared to take a break if they experience paradoxical anxiety as autonomic balance shifts to a new and healthier pattern.
Some home-use devices permit athletes to try different pacing rates and select the one that yields the greatest LF power. This allows individualizing the pacing rate for daily training.
Although not typical for healthy athletes, respiratory muscle strength training (RSMT) may improve diaphragmatic paced breathing following injury or other medical conditions. Musicians and vocalists often use portable devices to improve inspiratory and expiratory muscle function. Conceivably, these exercises might help long-distance tactical sharpshooters..
Focus and Attention
Optimal performance is more than excellent physical conditioning. The disciplined or trained capacity for heightened attention is essential to achieving optimal performance. HRV values are correlated with attentional capacity. Lower time-domain (e.g., RMSSD) and frequency-domain (e.g., HRV power) are correlated with inattention, higher anxiety, and diminished emotional regulation (Griffiths et al., 2017; Hsieh et al., 2010).
Stress and Anxiety
Optimal performance is more than excellent physical conditioning and focused attention.
Compared to healthy controls, individuals with anxiety conditions like PTSD show dominant very-low-frequency (VLF) and decreased HF power consistent with SNS arousal and reduced PNS activity (e.g., vagal withdrawal). The graphic below shows VLF power in red and HF power in blue.
Likewise, those diagnosed with stress-related conditions have lower time-domain measures (e.g., RMSSD, SDNN) than healthy controls (Cohen & Benjamin, 2006; Forte et al., 2021; Kim et al., 2018; Schneider & Schwerdtfeger, 2020).
When exposed to stressors, those with anxiety conditions have elevated resting heart rates observed during SNS activation. Faster heart rates reduce the time between successive beats and allow interbeat intervals (IBIs) to vary.
Performance goals vary with the performer and the athletic or non-athletic demand where excellence is required. Setting physiological performance goals may include motor speed but without errors. Continuous performance tasks measure omission and commission errors for this reason.
Speed may be secondary to accuracy. Attention that is highly focused to the point of tunnel vision may be less important than more open awareness of the viewer's periphery.
HRV values can be useful in monitoring the nervous system of an athlete or operator under demand conditions. HRVB can be instrumental in the pre-training and performance work-ups to improve autonomic and central nervous system flexibility.
HRV measures support optimal physical training by helping to identify the early signs of overtraining and even selecting the best times of day and training duration. HRV measures are best tracked by selecting similar times of the day and with paced breathing controls in place.
HRV measures recorded at daily or weekly intervals can give the athlete and coach a window into health trends that may signal early interventions to avoid injury or mood-related declines.
Randomized Controlled Trials
Dziembowska et al. (2016) found that among 41 healthy male athletes, those who received HRVB training showed improved physiological measures, decreased anxiety, and increased self-esteem compared to a control group.
Zafar et al. (2017) showed that a single 8-minute play on a biofeedback version of the Pac-Man game improved autonomic measures during gameplay and improved cognitive performance during a stressful task, suggesting that HRV and respiratory biofeedback can effectively improve mental capabilities during performance.
In a study by Paul et al. (2012), participants who received HRVB training showed statistically improved physiological measures and basketball shooting performance after 10 sessions compared to control and placebo groups.
Choudhary et al. (2016) found that track athletes who received HRVB training alongside regular practice showed significantly better physiological and performance measures over 10 weeks, including VO2 max, a common measure of physical fitness.
Aritzeta et al. (2017) demonstrated that HRVB combined with other relaxation techniques, significantly reduced anxiety and improved academic performance, with large effect sizes.
Clinical Efficacy
Based on five RCTs, Larson Ford and Sherlin (2023) rated HRVB for optimal performance as level 4 - efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.). Based on 5 RCTs, they rated neurofeedback as level 3 - probably efficacious in Evidence-Based Practice in
Biofeedback and Neurofeedback (4th ed.).
allodynia: a type of pain hypersensitivity where typically non-painful stimuli, such as touch or temperature changes, are perceived as painful. It is a symptom often associated with conditions like neuropathy, fibromyalgia, migraines, and postherpetic neuralgia, indicating abnormal processing of sensory information in the nervous system.
alpha asymmetry protocol for major depressive disorder: neurofeedback training to decrease left frontal alpha with respect to right frontal alpha.
angina pectoris a symptom of coronary artery disease characterized by chest pain or discomfort due to myocardial ischemia. Typically, it is described as pressure, heaviness, or squeezing pain in the chest, often radiating to the arm, neck, or jaw.
arterioles: small, branching blood vessels that lead from the arteries into the capillaries. They play a crucial role in the regulation of blood pressure and blood flow.
asthma: a chronic respiratory condition where the bronchial tubes become inflamed and constrict, leading to episodes of wheezing, coughing, and shortness of breath.
atheroma: A deposit or plaque within the intima of the arterial wall, consisting of lipids, cholesterol, cells (including smooth muscle cells and macrophages), and connective tissue.
biofeedback-assisted relaxation training (BART): multimodal treatment combining one or more biofeedback modalities with relaxation training (e.g., Progressive Relaxation).
blood pressure: the force exerted by circulating blood on the walls of the body's arteries, measured in millimeters of mercury (mmHg).
chronic bronchitis: mucus hypersecretion and chronic productive cough for at least 3 months for a minimum of 2 consecutive years.
chronic muscle pain: persistent or recurring discomfort or pain in the muscles, often associated with conditions such as fibromyalgia, infections, and autoimmune disorders.
chronic obstructive pulmonary disease (COPD): a progressive lung disease characterized by increasing breathlessness due to obstructed airflow from the lungs.
clinical efficacy: the ability of an intervention (e.g., HRVB for preeclampsia) to produce the desired beneficial effect in expert hands and under ideal circumstances, typically assessed in a controlled clinical trial setting. It may not always reflect real-world effectiveness, which takes into account variations in patient populations, adherence, and healthcare settings.
congestive heart failure (HF): a chronic condition where the heart does not pump blood as effectively as it should, often resulting in fluid build-up in the body, especially in the lungs and peripheral tissues.
coronary artery disease (CAD): a cardiovascular condition characterized by the narrowing or blockage of the coronary arteries due to atherosclerosis, reducing blood flow to the heart muscle.
cyclic vomiting syndrome: a disorder leading to severe and recurrent episodes of nausea, vomiting, and physical exhaustion, often with no clear underlying cause.
depression: a psychological disorder characterized by sadness, loss of appetite, energy, and interests, and problems with concentration.
diastolic blood pressure (DBP): the lower number in a blood pressure reading, representing the force exerted on artery walls when the heart is at rest between beats.
emphysema: the abnormal irreversible expansion of the gas-exchange airways associated with alveolar wall damage.
fibromyalgia (FM): a syndrome characterized by widespread musculoskeletal pain, fatigue, and specific tender points on the body.
functional gastrointestinal disorders (FGIDs): disorders characterized by chronic or recurrent gastrointestinal symptoms that cannot be explained by structural or biochemical abnormalities. The symptoms are believed to result dysfunctional brain-gut interaction. This category includes irritable bowel syndrome (IBS), functional dyspepsia, and functional constipation. FGID diagnosis is usually based on symptom criteria, such as the Rome IV criteria for IBS, and the exclusion of other organic diseases.
Generalized Anxiety Disorder (GAD): a chronic mental health disorder characterized by persistent and excessive worry about a variety of everyday problems, for a period of at least 6 months. The worry is disproportionate to the actual circumstances and is difficult to control. Other accompanying symptoms may include restlessness, fatigue, difficulty concentrating, irritability, muscle tension, and sleep disturbances.
hypertension: a chronic medical condition characterized by persistently elevated blood pressure, usually defined as a reading of 130/80 mmHg or higher.
hypoxia: a state in which the oxygen level available to tissues is below physiological needs, leading to cellular injury and death.
irritable bowel syndrome (IBS): IBS is a chronic functional gastrointestinal disorder typified by recurrent abdominal pain related to defecation or accompanied by changes in bowel habits. Its subtypes include IBS with predominant constipation (IBS-C), diarrhea (IBS-D), and mixed (IBS-M). The precise pathophysiology remains unclear, but proposed mechanisms include altered gut motility, visceral hypersensitivity, low-grade inflammation, post-infectious changes, altered gut microbiota, and gut-brain axis disturbances. Diagnosis is clinical, often based on Rome IV criteria, and requires ruling out other organic diseases.
mediational model of muscle pain: hypothesis that lack of assertiveness and resultant worry each trigger sympathetic activation.
multi-modal strategy: a training or treatment protocol combining several components (e.g., mindfulness meditation and HRV biofeedback).
myocardial ischemia: a condition characterized by reduced blood supply to the heart muscle, typically due to coronary artery disease, leading to inadequate oxygenation and potential damage to the myocardial tissue.
myocardial infarction (MI): a medical condition characterized by irreversible necrosis of heart muscle secondary to prolonged ischemia, typically resulting from an abrupt decrease in coronary blood flow due to occlusion of a coronary artery.
optimal performance: the highest level of functioning or performance an individual is capable of achieving, often used in the context of athletic or cognitive performance.
Post-Traumatic Stress Disorder (PTSD): a psychiatric disorder that may occur in people who have experienced or witnessed a traumatic event such as a natural disaster, a serious accident, a terrorist act, war/combat, rape, or other violent personal assault. Symptoms can include intrusive memories of the traumatic event, avoidance of reminders of the trauma, negative alterations in mood and cognition, and marked alterations in arousal and reactivity, such as hypervigilance or an exaggerated startle response. The symptoms last for over a month and cause significant distress or impairment in social, occupational, or other important areas of functioning.
preeclampsia: a potentially dangerous pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys.
primary hypertension: also known as essential hypertension, this is the most common type of hypertension, usually developing gradually with no identifiable cause.
recurrent abdominal pain (RAP): at least 3 episodes of often severe abdominal pain over 3 months; diagnosed in up to 30% of children ages 4 to 12.
secondary hypertension: hypertension due to an underlying condition like kidney disease or hormonal disorders and typically appears suddenly and results in higher blood pressure levels than primary hypertension.
specific phobia: a type of anxiety disorder characterized by a pronounced fear or anxiety about a specific object or situation, leading to avoidance behavior. The phobic stimulus provokes immediate fear or anxiety, and this response is recognized by the individual as being excessive or irrational. Examples include fear of flying (aviophobia), fear of spiders (arachnophobia), and fear of blood (hemophobia). Specific phobias can significantly affect an individual's daily activities and quality of life, despite being often overlooked in clinical practice.
stroke rate: also referred to as heart rate, this is the number of heartbeats per minute. It is the number of times the heart contracts or "strokes" to pump blood in a minute.
stroke volume: the amount of blood pumped from the left ventricle of the heart with each beat.
systemic vascular resistance: the resistance to blood flow offered by all of the systemic vasculature, excluding the pulmonary vasculature. It is determined by factors like vessel diameter, vessel length, and blood viscosity.
systolic blood pressure (SBP): the higher number in a blood pressure reading, representing the force exerted on artery walls when the heart contracts or beats.
tender points: places on the body where light pressure causes pain, often associated with fibromyalgia.
thrombus: a solid or semi-solid blood clot that forms within the vascular system, often at sites of blood vessel injury or turbulence and may cause occlusion of blood flow.
trigger points: specific spots in the muscle which, when pressure is applied, trigger pain in a different area of the body. These are often found in people with myofascial pain syndrome and fibromyalgia.
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For Biofeedback, BioSource Software offers Human Physiology to satisfy BCIA's Human Anatomy & Physiology requirement. For Neurofeedback, BioSource provides Physiological Psychology to satisfy BCIA's Physiological Psychology requirement.
BCIA has accredited each course, and they combine affordable pricing ($150) with industry-leading content.
Assignment
Now that you have completed this module, identify the clinical applications treated in your practice that might benefit from HRVB? Which HRV interventions are you already using?
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