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The Autonomic Nervous system

The Autonomic Nervous system is a part of our nervous system which controls bodily functions. It does this without the need for us to consciously control it - unlike if we tried to move our arms or say something. Lots of bodily functions are influenced by the autonomic nervous system: including temperature control, heart rate, blood pressure, digestion, breathing etc.

Normally, the autonomic nervous system is kept balanced by two different branches. The sympathetic branch (you may know as the ‘fight or flight response’) and the parasympathetic (also referred to as ‘rest and digest’).

These 2 branches keep your bodily functions in balance and adjust depending on what requirements your body needs. For example, if you need to run fast, the sympathetic branch will cause your heart rate to increase to increase blood flow and oxygen delivery to your muscles. Once you stop running, the parasympathetic nervous system acts to slow the heart rate, returning to a resting state.

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For some people with Long COVID, the usual balance between the 2 branches is lost. This is referred to as dysautonomia (“dys-” meaning dysfunction, and “- autonomia” the autonomic nervous system). With the balance disrupted, simple tasks can cause people to have inappropriate responses of their bodily functions such as having a faster heart rate while walking for example.

They may find they are prone to develop palpitations; digestive problems; change in sweating or temperature regulation; feel ‘on edge’ during a flare of Long COVID symptoms. As you can see from the diagram, lots of bodily functions may be impacted by the balance being out of sorts. There is ongoing research into how much this contributes to many of the symptoms experienced in Long COVID.

One way of looking for signs of dysautonomia is doing a test called a sit-to-stand test which is part of your initial assessment. This shows how your heart rate responds to exertion. You may need to have your blood pressure and heart rate measured lying and standing. Other investigations such a 24hr-holter (a wearable heart monitor) or a six-minute-walk test or tilt test might be requested to investigate further. The results of these can help us to understand how your body is managing the balance of the autonomic nervous system.

Most people find their symptoms improve with time. During this recovery period, there may be ups and downs with symptoms being better some weeks and worse others.

Activities which encourage parasympathetic or ‘restful’ activation can be useful to reduce the effects of dysautonomia and the likelihood of bad weeks. These include relaxation techniques, meditation, breathing exercises etc. Your therapies team will help you figure out what might work best for you.

  • Developing an awareness of situations likely to cause symptoms e.g. standing in hot weather or exercising after a large meal.
  • Take action at the onset of symptoms by sitting, crouching or laying down, drinking water and returning to normal activity slowly.
  • Head up tilt on the bed overnight ideally by putting additional support under the mattress or raising the legs of the bed.
  • Maintaining a good fluid intake, drinking 500mls immediately when getting out of bed and then sipping enough fluid to keep urine a pale-yellow colour.
  • Taking adequate dietary salt.
  • Developing a good situational awareness of the factors likely to be associated with lower blood pressures. These include warm environments, prolonged standing, pain, stress, large meals, hypotensive medications,
  • alcohol and factors associated with elevations of intra- thoracic and intra-abdominal pressures (for example coughing, laughing, straining to pass a bowel motion and micturition).
  • Avoiding postures likely to create symptoms such as standing still, bending over or raising arms above head e.g. hanging washing on a line.
  • Making the use of calf pump exercises (simple heel lifts) before getting out of bed or before standing or if standing still a habit.
  • Eating small meals, avoiding sugary foods and being cautious with alcohol.
  • Find ways to do as many daily activities as possible sitting including showering.
  • Pace daily activity to enable a brief rest and chance for circulation to recover from exertion.

For a small group of people, their dysautonomia might be significant enough to consider medication to control their heart rate response. This is considered after thorough discussion with your Post-COVID team and investigations to understand if this might be helpful.

If you are at the stage where you wish to try exercise, you might benefit from a slightly altered approach to returning to exercise including utilising non-upright/recumbent exercise initially before progressing to more upright exercise.

Exercise that increases muscle tone, particularly in the lower body, will improve circulation. This can improve autonomic symptoms. You should discuss with your GP and/or physiotherapist, the best kind of exercise particularly if you have other health problems but this evidence-based guidance should be incorporated when you exercise.

It is important to start exercise that reflects your current state of exercise or activity tolerance, even if you have been fitter or more active in the past.

Which exercise is good?

  • Use exercises that focus on improving the strength of leg and the core muscles of the abdomen (Pilates-type exercises).
  • Choose strengthening exercises you can do when sitting down or lying down rather than standing. Adapt exercises to avoid standing still or raising arms over head while standing.
  • It is beneficial to gently increase your cardiovascular exercise. This could include using floor pedals or a recumbent/reclining bike. For those who able, a rowing machine or gentle swimming could be beneficial.
  • Floor pedals could be used in sitting, recumbent or near lying for those needing to work at this level fitness. Start in a recumbent/reclined position before transitioning to upright exercise. Start at a gentle level, for a time that you can tolerate. For some, this might just be one – two minutes, for others 5-10 minutes. Build this up over a few weeks or months until you can reach 30 minutes in reclined and then progress to standing exercise.
  • If attending group exercises classes, go at your own pace, don’t try to keep up with everyone. Make sure you inform the instructor ahead of time.
  • In the gym, get a thorough induction and choose equipment that you can use seated.
  • Swimming or walking in the water is also useful, remember to save energy for getting ready afterwards.

Once comfortable with the first exercise plan there are a range of ways to improve your ability to exercise by doing ONE of the following:

  • Increasing the length of time you exercise each session.
  • Increase the number of sessions you exercise in a week.
  • Increase the intensity of part of each exercise session.

For instance, if you have been doing three minutes of stationary cycling three times a week you can do one of the following;

  • Increase to 4 minutes of cycling, three times a week or
  • Cycle for 3 minutes four times a week or
  • If you are working at 50% of your maximum effort you could try and increase that slightly to 60% for one minute of cycling each session.

  • Set realistic exercise targets recognising that it is likely to take you longer than an average person to regain some of your exercise conditioning because of your health conditions.
  • Choose the type of exercise and the times you exercise so that you can do it regularly. Consistency is key.
  • Exercise when you are well hydrated and stop and rest if you feel unwell with autonomic symptoms or have excessive pain. Ensure you also keep salt or electrolytes appropriate if drinking more water.
  • Monitor your symptoms, do not overexert leading to an increase or flare in your symptoms.
  • Use a bad day as a baseline and think what you can realistically do in terms of exercise. This is your starting point, then you can slowly build up. Don’t be tempted to increase on a good day, as it can lead to cycles of boom and bust.
  • Being prepared to be flexible and do shorter exercise sessions on the days you feel very unwell.
  • Making exercise fun, think about exercising to music or with a friend.
  • Most importantly, you cannot exercise or push your way through the symptoms, this often makes things worse. Titrate the level of activity according to your symptoms.