To test a potential use of biofeedback in the clinical setting, a group of researchers studied the effect of biofeedback on young adults with prehypertension. According to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure, prehypertension is defined as a blood pressure that is between 120/80 and 139/89.  31% of U.S adults have prehypertension. The researchers randomly assigned 43 prehypertensive young adults to a Heart Rate Variability (HRV) biofeedback group, a slow abdominal breathing group and a control group.  Heart rate variability is a measure of the difference between the maximum heart rate and the minimum heart rate during one breath cycle.  Inhalation stimulates the sympathetic nervous system and therefore increases the heart rate.  Exhalation stimulates the parasympathetic nervous system and therefore lowers the heart rate.    Everyone has a certain breath rate that maximizes their heart variability.  Most people will maximize the difference between heart rates at a breathing rate of 6 breaths per minute (10 seconds per breath).  This is something you can try right now.  Lie down on a couch or a bed and get comfortable.  Put one hand on your abdomen and breathe slowly into your abdomen for 5 seconds then exhale slowly for 5 seconds. Do not take deep breaths. If you feel lightheaded or uncomfortable, you are most likely breathing too deeply.  Shallow breaths that bypass the chest en route to the abdomen are best.  Repeat 20 times then remove your hand from your abdomen and feel your pulse.  Continue to breathe abdominally with a 10 second breath cycle.  Notice how the pulse quickens when you inhale and slows while you exhale. This exercise amazed me. If you did not notice a difference, do not worry.  Repeat this exercise twice a day and eventually you will feel the difference. Breath pacers, which can be found online or as an app on your smart phone, are helpful when practicing abdominal (also known as diaphragmatic) breathing.

     In the study, the abdominal breathing group performed this same exercise with biofeedback practitioners 10 times over a five week period. They were also advised to practice on their own for a 20-minute period twice a day, every day. When the HRV biofeedback group met with biofeedback practitioners, they were instructed to breathe abdominally for 2 minutes at each of five specific breath rates (6.5, 6.0, 5.5, 5.0 and 4.5 cycles per minute) while their HRV was being measured.  Once the researchers determined each individuals ideal breath rate (the one that maximized their heart rate variability), the participant was advised to use a breath pacer to practice abdominal breathing at that rate (their resonant frequency) for 20 minutes twice a day. The ideal breath rate was re-evaluated at each of the 10 meetings during the five week period.  If the patient’s resonant frequency changed, they were advised to breathe at their new ideal breath rate using a breath pacer when practicing at home. The participants were also able to watch their HRV as it was being measured during the 10 sessions and were instructed to try to increase HRV while breathing at their resonant frequency. When the control group met with the practitioners for 10 sessions during the 5 week period they were told to sit and breathe naturally. At the end of the five week period, participants in the HRV biofeedback and abdominal breathing group were instructed to continue their daily practice at home with a breath pacer until the 3 month follow-up. 

     At the end of the five week period, blood pressure in the HRV biofeedback group decreased and the change lasted for at least 3 months. The abdominal breathing group also significantly decreased their blood pressure and at the 3 month follow up their BP was steady. The control group showed no significant differences. 

     This randomized controlled pilot study is one of the first to assess the effects of HRV biofeedback on prehypertension. Overall, the results showed that prehypertensive patients can lower their systolic BP by 13.8 mm Hg and their diastolic BP by 7.2 mm Hg after 10 sessions with a biofeedback practitioner. This study also showed that the BP-lowering effects last for at least 3 months post treatment.  This technique is ‘user-friendly’ and has no adverse side effects.  There are innumerable uses for biofeedback such as pain management, asthma management and stress / anxiety management.  Many naturopathic doctors are either trained in biofeedback or know a good doctor who is trained.  Consult your physician if you want more information about biofeedback.

Lin, Guiping, Qiuling Xiang, et al. "Heart Rate Variability Biofeedback Decreases Blood Pressure in Prehypertensive Subjects by Improving Autonomic Function and Baroreflex." Journal of Alternative and Complementary Medicine. 18.2 (2012): 143-52. Print.