What is Biofeedback?
Biofeedback is a broad modality of treatment centered on the use of technology to provide information about your biological processes with the aim of using this information in improving your health. Biofeedback can provide you with information on many measurable physiological processes including:
Skin conductance (also known as galvanic skin response). This is a measure of the electrical conductivity of the skin, typically measured with electrodes placed on the fingers. When the sympathetic nervous system (stress response) is aroused, sweat glands in the hands are activated. The skin becomes more conductive (sweatier) when you are in an aroused state.
Skin temperature. Typically during a relaxed state, skin temperature in the periphery, e.g. the hands, is higher. When we enter a period of stress, peripheral vasoconstriction (i.e., the blood vessels in your hands get narrower) occurs and sends more blood to the key areas of the body, the internal organs, brain, and large muscles. Thus warmer hands generally indicate a more relaxed state. Vasoconstriction is caused by stimulation of the sympathetic nervous system (see Autonomic Dysfunction); vasodilation is caused by relaxation of the sympathetic nervous system.
This is looking at the electrical activity of muscles, from the surface of the skin, using electrodes placed on the muscle belly. We can use this information to increase voluntary control over muscle activity. For example, often adults hold tension in some of the muscles of the neck and upper back, which sometimes contributes to tension headaches, so we could train this down. If we were to ask you to reduce the tension in your trapezius muscles, that may seem too abstract. So, if we measure the tension (in mV) and represent that tension pictorially (say like a balloon floating higher into the sky as the tension goes up) or auditorily (say the pitch of the sound increases as the tension goes up), patients get feedback on their muscle tension levels. Once people become aware of their muscle tension levels, they start to learn how to control them. Often, for patients, we try to train down the muscle tension in muscles that are overused, and train up (or engage) muscles that are underutilized.
Respiration. There are several methods to measure respiration, a capnometer can measure the concentration of carbon dioxide in exhaled air, or a band placed around the abdomen can measure the amplitude of diaphragmatic breathing. Respiration rates typically increase during sympathetic activation (stress). Breathing at the optimal, or resonant frequency, with the correct pattern, and correct muscle recruitment, can be trained.
Heart activity. This can be measured with EKG sensors placed on the chest or with a blood volume pulse sensor placed on the finger (measures heart rate through looking at the volume of blood that passes through tissues). Generally, heart rate increases with sympathetic arousal (stress). We can monitor this and train heart rate variability.
So what is the big deal with learning how to warm up your fingertips? Or some of the other processes we mentioned? The topics of respiration, heart rate variability, muscle tension, and skin conductance/temperature are large topics in and of themselves. Each topic has its role in improving your general health.
For example, in skin conductance and skin temperature, it is not so much the effect that matters (i.e., decreasing your sweatiness or increasing your temperature), it is training the (autonomic neurological) process that results in these effects that matters. The effect is just a gauge we use to provide feedback on your ability to notice and influence your autonomic neurological system. It so happens that by gaining this control, you can influence many areas of your general health and treat specific health conditions, more below.
In the case of breath training, are you breathing appropriately? Are you taking in too much oxygen and blowing off too much CO2? This is known as overbreathing and is very common. Overbreathing can develop when circumstances force you to change how you breathe, and this then becomes the new normal. One such situation could be a series of stressful events, which cause us to modify our breathing to adopt those patterns and behaviours associated with the stress response (e.g. increased rate of respiration, recruitment of the chest and shoulders). Perhaps allergies or a sinus infection may have caused us to mouth breathe, which encourages over breathing. Over time those breathing practices that may have been effective in the moment can become a learned behaviour .
The implications to your health are significant. The rate at which you breathe is connected directly to the pH of your blood, if you over-breathe, this can be disrupted and can result in inefficient nutrient exchange and metabolism of your body’s cells and your brain. Over breathing in the long-term can be related to, may trigger, exacerbate, or contribute to panic disorder, hypertension, heart arrhythmias, migraine and tension headaches, sleep apnea, IBS, fatigue, learning and attention deficits, chronic pain, asthma, epilepsy, anxiety, and anger (Khazan, 2013).
There are several reasons to train your breathing:
- Using your diaphragm, rather than using muscles in your neck and chest wall, can help increase your core strength and lessen neck pain/stiffness and headaches.
- Breathing at an appropriate pace and depth will help provide your organs with ideal amounts of oxygen. In moderate overbreathers there is a 30-40% reduction of O2 to the brain and in severe overbreathers this amount can go up to a 60% reduction of O2 to the brain (Khazan, 2013).
- To breathe at an appropriate pace and depth will help regulate your blood CO2 levels. Blood CO2 levels help regulate your blood pH, the ionic potential organs see, and in turn, organ function. Biofeedback measures again can look at the effect – using a capnometer to look at the CO2 concentration in the air you exhale – or the cause – using biofeedback technology to train the ideal pace.
Ideal breathing is the cornerstone to HRV training, a method training responsiveness and balance of your autonomic nervous system.
For sEMG, biofeedback applications are more intuitive. Dr. Erik Peper’s study (Peper et al., 2010) showed that there was a 66% lifetime prevalence of neck pain among adults, 90% of college students reported discomfort by the end of the semester, and at least 30% of people working at the computer reported back, neck, hand and arm pain. Many of us can surely relate to situations that resulted in unexpected muscle tension. This is largely as a result of unintentionally recruiting muscles excessively in tasks where it is not necessary. These tasks can be simple tasks that we do all the time like walking, talking, sitting, typing, texting, chewing, thinking, recalling, etc. In concussion patients there may be other areas that lead to excessive muscular effort like activities that require balance, being in visually stimulating areas or just using one’s visual system. Resultant muscle tension can lead to or worsen headaches, neck pain, back pain, TMJ pain, etc. In concussion patients, everything is interdependent, so this can lead to worsening quality of attention, balance, vision, mood, sleep, energy, and difficulty with complying with rehabilitation recommendations.
The first step in biofeedback is to gain insight into these biological variables. Sometimes we look at just raw data with biofeedback, for example the structure or patterns of breathing to help us understand how this relates to your clinical picture.
The next step is learning which processes you have control over, and which are truly out of your control. We used to believe that many of the physiological processes were controlled unconsciously, by homeostatic systems, but now we know that you do have conscious control over many of these systems. You can control all of the systems listed above. You can control the electrical activity of your heart, respiration, skin conductance (sweat), skin temperature, and your muscles. That being said, there are also things that you can not control, and in this case acceptance of this will be important. Some understanding of mindfulness (provide links to mindfulness defined) goes a long way in facilitating biofeedback training.
Once we have the insight, and we know what we can control, we can begin to practice regulating these processes. As with almost any sort of training, practice at the appropriate level of challenge is necessary to build skills and control over these processes. For example, if we are working on respiration, we begin with learning the skills and proper muscle recruitment, then we can begin to change the structure and patterns of breathing, and only then do we begin to slow the pace of breathing down. Or perhaps we are working on reducing muscle tension in the upper back, we would gradually lower the threshold for the electrical activity in those muscles.
In biofeedback training works using the same principles as operant conditioning, using reinforcement to up-train or down-train a response. Feedback will be provided when the individual undergoing training reaches either a level of the physiological measure that is determined to be not desirable (e.g. hearing a loud beep when muscle tension rises too high) or in the targeted range (e.g. seeing a graphic play when breathing is at the appropriate pace). We use both visual (e.g. working on warming the skin temperature in your hand and use a graphic where the warmer your hands are, the larger the flame in the image) and auditory (e.g. play a tone when you tense the muscles in your neck during an exercise) feedback depending on the need of the individual.
Biofeedback and Concussion
Concussions are complex. Its effects are variable, interdependent and often pervasive, impacting many neurological systems.
The impact of concussion on the autonomic nervous system (ANS) is one that has just begun to be explored. In a recent literature review on that subject, it was found that there is evidence to suggest that concussion does likely impact the function of the autonomic nervous system (Pertab et al., 2018). The mechanism of this effect may be physical, perhaps some of the structures involved in the ANS are damaged during the impact, regardless, this autonomic dysfunction likely contributes to some of the persistent symptoms and the nature of recovery. Biofeedback can be used as a tool to gain insight into, and to regulate, the ANS. Subsequently, if we can target ANS dysregulation with biofeedback, it follows that this should aid in reducing the severity or duration of some of the post-concussion symptoms. In individuals with brain injury, HRV and biofeedback training may help regulate emotion, and improve cognition (Kim et al., 2013).
The research in this field, of biofeedback and concussion, is just beginning. Concussion is currently a hot topic in research, as is biofeedback, and hopefully in a few years we will see more evidence and will be able to refine our biofeedback protocols even further. A majority of the research that looks at biofeedback and concussion, focuses on HRV. We know that HRV is likely impacted in individuals with concussion or mild traumatic brain injury (Thompson & Hagedorn, 2012). We also know that it is important to look at an individual holistically, one’s brain does not exist in isolation from one’s body, or heart. Some preliminary research has shown promising effects in positively impacting mood and emotion regulation, postconcussion symptoms, and decreasing headache severity. (Lagos, Thompson, & Vaschillo, 2013). Conder and Conder (2014) in their review of HRV and concussion, concluded that biofeedback was an effective intervention for targeting HRV after concussion, and that this would then likely have a positive impact on cognitive performance.
Biofeedback is a therapy that has been used successfully to treat a large variety of clinical diagnoses including, but not limited to:
- Mental health and psychiatric disorders. Biofeedback can facilitate symptom reduction, in disorders such as anxiety, autistic spectrum disorders, depression, dissociation, eating disorders, schizophrenia and psychosis (Schoenberg & David, 2014).
- Stroke (Stanton, Ada, Dean, & Preston, 2017)
- Pain: fibromyalgia (Glombiewski, Bernardy, & Häuser, 2013), low back pain (Matheve, Brumagne, & Timmermans, 2017), migraine and headache (Andrasik, 2010).
- Insomnia (Taylor & Roane, 2010)
- Asthma (Lehrer et al., 2004)
- Incontinence: urinary (Herderschee et al., 2011) and fecal (Vonthein, Heimerl, Schwandner, & Ziegler, 2013)
- Coronary artery disease (Climov et al., 2014)
- Cerebral palsy (MacIntosh et al., 2018)
Biofeedback has also been used to target:
- Optimal sport performance in athletes (Jiménez Morgan & Molina Mora, 2017) and cognition in athletes (Rusciano, Corradini, & Stoianov, 2017)
- Balance in older adults (Alhasan, Hood, & Mainwaring, 2017)
Although, it should also be noted that one’s recovery from the above diagnoses, does not always hinge on biofeedback alone. There are many other treatment modalities that are as effective, or more effective, for the above diagnoses. That being said biofeedback can be a very useful tool and promote recovery for many individuals.
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Andrasik, F. (2010). Biofeedback in headache: An overview of approaches and evidence. Cleveland Clinic Journal of Medicine, 77, S72-S76. doi:10.3949/ccjm.77.s3.13
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Stanton, R., Ada, L., Dean, C. M., & Preston, E. (2017). Biofeedback improves performance in lower limb activities more than usual therapy in people following stroke: A systematic review. Journal of Physiotherapy, 63(1), 11-16. doi:10.1016/j.jphys.2016.11.006
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Vonthein, R., Heimerl, T., Schwandner, T., & Ziegler, A. (2013). Electrical stimulation and biofeedback for the treatment of fecal incontinence: A systematic review. International Journal of Colorectal Disease, 28(11), 1567-1577. doi:10.1007/s00384-013-1739-0
Last update: September 2018