All About Postural Orthostatic Tachycardia Syndrome (POTS)
What is Postural Orthostatic Tachycardia Syndrome (POTS)?
Postural Orthostatic Tachycardia Syndrome (POTS) is a medical condition whereby an individuals’ heart rate significantly increases when moving from a lying to a standing position.
When a healthy individual transitions from lying to standing, fluid in the blood (but not blood itself) transitions from blood vessels to the interstitial space (the space in between blood vessels & organs). This results in reduced circulating blood volume. Reduced blood volume then means that with each heart beat, less blood is pushed around the body (this is known as a reduction in stroke volume). Normally when stroke volume reduces, there occurs a compensatory mechanism (a response from the sympathetic nervous system, the “fight or flight” pathway), to increase heart contractility (the force of each heart beat) and heart rate. Together, this response boosts stroke volume back up, so that sufficient blood can continue to be pushed around the body, despite standing.
Individuals who have POTS experience the normal, initial reduction in stroke volume when they transition from lying to standing, just as a healthy person does. An individual with POTS will also have a compensatory response from the sympathetic nervous system to try and increase heart contractility and heart rate. A person with POTS, however, does not experience an increase in stroke volume as a result of this response. They get an increase in heart rate, but not an increase in stroke volume.
An individual with POTS may experience a heart rate increase of 30bpm or greater within the initial 10 minutes of standing. There are many unpleasant symptoms associated with POTS, including but not limited to fatigue, dizziness, headaches, heart palpitations, sleep disturbances, anxiety and nausea.
POTS predominantly affects premenopausal females between the ages of 15 and 50. The global prevalence of POTS (in developed countries) is estimated to be between 0.2 and 1%.
POTS is a complex condition, and there are different potential causes, each characterising a certain sub-type of POTS.
According to Zhao & Tran (2011), there are 5 sub-types of POTS:
1. Neuropathic - POTS associated with dysfunction of the autonomic (involuntary) nervous system.
2. Hyperadrenergic - POTS associated with dysfunction of the body’s system that regulates the hormone norepinephrine.
3. Hypovolemic - POTS associated with reduced blood volume and/or overall body fluid levels.
4. Autoimmune - POTS associated with dysfunction of the immune system.
5. Deconditioning - POTS associated with overall physical and cardiovascular deconditioning.
Considerations and Precautions with POTS
As mentioned, there are many unpleasant symptoms that may be associated with POTS:
- Severe and/or prolonged fatigue
- Light-headedness (and potentially fainting)
- Dizziness
- Nausea and vomiting
- Headaches
- Forceful or palpitating heart beats
POTS is not life-threatening. However, there are some considerations associated with the symptoms that may be experienced. For example, head trauma from a fall following fainting or feeling dizzy.
Things like caffeine can affect the severity of POTS symptoms, and therefore caffeine intake may need to be considered and monitored (Zhao & Tran, 2011).
Exercise and POTS
Individuals with POTS can certainly exercise. In fact, it is recommended that all individuals with POTS exercise. This is because exercise improves the management of POTS (Zadourian et al., 2018). It has also been shown to improve heart function (Fu & Levine, 2015). Exercise is also important as individuals with POTS typically have a lower physical fitness level (Fu & Levine, 2015).
There are, however, a few considerations that must be taken into account. For example, given the symptoms that an individual with POTS may experience, it is recommended to begin with supervised, low-intensity exercise whereby upright positions are avoided (e.g. rowing, swimming, recumbent bike) (Zadourian et al., 2018). It is recommended that as capacity improves, the duration and intensity of exercise is gradually progressed, and upright exercise can be gradually added as tolerated.
There are also techniques that can be used to assist with the management of the acute symptoms of POTS. For example, leg crossing, muscle pumping or squeezing a rubber ball.
It is safest for an individual with POTS to exercise under the guidance of an exercise physiologist. Exercise physiologists are allied health professionals who are able to work alongside individuals with chronic illnesses, such as POTS, to enable them to exercise safely and effectively.
A Closer Look at the Levine and Dallas Protocols
Two exercise protocols that have been developed specifically for the management of POTS are the Levine and Dallas Protocols. These protocols help individuals with POTS build their physical capacity while minimising symptom exacerbation.
The Levine and Dallas Protocols are 8-month programmes that incorporate both aerobic and strength training. They lay out a step-by-step guide to exercising with POTS, giving you individual formula-based heart rate zones (to assist with finding the appropriate intensity for exercise), frequency of exercise, duration of exercise and what type of exercise to do.
The Dallas Protocol is essentially the same as the Levine Protocol. Only the Levine Protocol, however, includes guidance for “Pre-Month 1” and “Pre-Month 2”. This assists individuals who have severe exercise intolerance.
While exercise can be hugely beneficial it should always be overseen by an exercise professional familiar with POTS. This enables them to monitor your symptoms and progress and make appropriate amendments to your program as required in a safe manner. If you would like to know more please contact 85443231 and ask to speak to one of our experienced Exercise Physiology team.
Written by Brandon Coorie