By Sharon Niv, Ph.D.
Biofeedback is a physiological therapy technique that is over a century old. It refers to an array of approaches by which individuals learn to become more aware of their body’s physiology and hence to gain more control over it. Biofeedback techniques have been used successfully to treat such conditions as hypertension, incontinence, PTSD, and others. Biofeedback devices currently on the market run the gamut in terms of targeted physiological functions.
These days, one of the most popular approaches targets Heart Rate Variability (HRV), which refers to the difference in pulse between the in-breath and out-breath. Despite the term ‘heart rate,’ our pulse is usually not uniform, with faster beating pulse when we breathe in and a slower one when we breathe out. In fact, having a heart rate that is too steady is indicative of heart disease. Optimal HRV is relatively large, and indicates healthy vagal tone, which leads to healthier organ functioning and a calmer nervous system. Devices that train HRV include Emwave2, Zen by Zinc Software, and Inner Balance Sensor.
However, HRV is not the only physiological mechanism that has been targeted for feedback. For example, skin conductance response (SCR) refers to the conductivity of the skin, which changes when sweat glands on the skin, usually on the fingers, respond to anxiety and unpleasantness. A biofeedback goal with SCR goal is to reduce this conductivity and hence reduce response to anxiety and pain. Some approaches target heart rate directly rather than HRV, with the goal of reducing blood pressure and pulse. Even muscular tension can be targeted with a measure like electromyography (EMG), and can be used to reduce pain due to tension, such as headaches or TMJ.
Although all of these methods have been researched, there have been few if any direct comparisons of the different targets, and so it is difficult to deduce whether they have substantially different potential for body mastery and stress relief. Research has largely support biofeedback with HRV for vagal tone, emotional well being, anxiety, and stress relief; HR for heart health, blood pressure reduction, and stress reduction; SCR for anxiety and pain; and EMG for headaches, tension, and TMJ.
As technological attention shifts toward personalized medical devices, we can anticipate a surge in available options geared at helping us gain control over our physiology in order to optimize our health and well-being.