Sympathetic Nervous System stuck on "high" setting

OK, bit of a long shot as I’m in “already consulted a doctor” territory, but perhaps someone might have some insight or experience. Basically I’ve been unable to train for over a month now because of underlying health issues that I can’t fully identify.

I can identify where they started - I had a head cold in mid-December, and seemed to be on the road to recovery from that when I had some asthma symptoms as an allergic reaction to a cat at my in-laws’ place at Christmas. However while the acute symptoms have been gone for several weeks, and I even had a course of antibiotics in case of a lingering infection, everything points to my sympathetic nervous system still being in overdrive. Symptoms include:

  • Elevated resting HR (see screenshot below)
  • Depressed HRV (see second screenshot)
  • Elevated respiration rate
  • Constipation
  • Abnormally fast and high HR response to exercise or any physical activity
  • Shortness of breath (but not really asthmatic “wheezing”), especially during physical activity

Any thoughts on causes or even solutions? I have had some stress recently but no more than I’ve managed before. And it’s worth saying that an acute allergic asthmatic response is not uncommon for me, and neither is a cold - but normally I recover from them within a day or a few days at most and am able to resume training pretty quickly. I’m getting as much rest and sleep as I can but it just doesn’t seem to be improving.
(Edit: antibody and other tests show that I haven’t had Covid. Had vaccine booster in November but it had little impact and resumed training within a few days)

Maybe it’s totally unrelated, but have you had a covid vaccine in that same period of time? Because I had very similar symptoms after getting the second dose and it took over a month to get back to “normal” training.

Otherwise, I don’t have experience with asthma and a common cold surely isn’t the cause of something like that.

1 Like

Was it a cold, or could it have been covid?

In any case, I’d think the answer will unfortunately be “more rest”.

Should have mentioned the Covid-related factors!

Vaccines - had one mid November, and as per screenshots, had maybe a small rise in RHR but then went down again.
Actual Covid - have never had Delta or Omicron, test regularly and even paid for an antibody test which showed I have antibodies from vaccination, but none from recent or historic infection.

1 Like

So obvious disclaimer of I am neither a doctor nor did I stay at a Holiday Inn Express last night but I can give you my personal anecdote of clawing my way out of a similar hole. I also didn’t have any unusual stressors or excessively hard training but I had a high resting heart rate and depressed HRV (by almost 20% if my metrics are to believed) and I had to find some things that helped me:

  1. Rest - you’re already doing that but keep doing it.
  2. Light Endurance activities - really light, I was doing some very easy Z1 rides and gradually extending the duration. At the end of each ride I would note if I felt better than when I started or not. I usually did.
  3. Electrolytes - I dont usually salt my food and do most of my own cooking. I started tracking in MyFitnessPal to see my trends (only takes a week or so of tracking to get an idea) and I was chronically low on sodium relative to the recommended daily value even before accounting for what training I was doing.
  4. Protein - My tracking showed I was woefully under consuming protein. I’ve worked my way up to .8-1g of protein per pound of body weight

These couple things saw a drastic improvement in my sleep, my HRV and my resting heart rate after a couple weeks. Not saying it’ll fix your issues but it’s some other ideas to consider evaluating for yourself.


Thanks, really appreciate the response.

My suspicion is that this will ultimately be the answer, along with “patience”. I’m mostly posting in the forlorn hope that there might be some other cause/solution I’ve missed in my Googling…

At the moment, this has been a struggle. The last session I did (a week ago) was only 30-45mins at Z1, and I felt drained and tired afterwards - and the next morning my RHR had leapt back up and my HRV had taken a nosedive. I’m waiting until I see a bit more improvement in the underlying metrics before I risk anything more than going for a walk.

On the protein point, I do get some, but probably have reduced my intake as I’m not having recovery shakes currently. So would certainly do no harm to go back to more of that. As for salt, I’m afraid it can’t be that as I do my own cooking and absolutely hate under-seasoned food!

No, I shall consider this. I did have a negative HR response to the first two vaccines, though (1) neither of them prevented me from training, and (2) I want to be careful not to start disregarding factors that make more circumstancial sense, i.e. the cold and allergy episodes.

Yikes, lets make sure we are keeping the dialogue directed at what we host the TrainerRoad Forum for:

‘This is a place to talk about all things bike or triathlon related (including nutrition and weight training).’

Medical advice from not doctors = potentially harmful and not under our Community Guideline of ‘Constructive Contribution’.

Thanks for staying on topic.


Yes, absolutely - as per my original post I am looking for “insight or experience” that at most, might help me find the right avenue to get the professional medical advice I need to start training again. Not actual medical advice.

And to be fair I don’t think anyone has offered anything other than clearly-sensible advice about rest and nutrition, or raised possible avenues to explore. But I certainly won’t be doing anything drastic at the say-so of non-doctors!

1 Like

I would just add that activity to work on switching off the sympathetic system might be worth exploring - some mindfulness meditation and/or breathing exercises aren’t a silver bullet but probably can’t hurt either. Good luck, I don’t envy you.


I would consult with your family doc about doing some blood work. Particularly around a thyroid panel to look at TSH, T3, T4, and maybe a DUTCH test to look at adrenal health. Its possible training and poor recovery (overtraining) can dig you into a hole in this area in addition to extra stress.

I’m a DC that practices structural correction as well as functional medicine/bio-energetic testing. I can’t tell you how many patients I see that have sympathetic/parasympathetic imbalances. These imbalances lead to malfunction, dis-ease process and symptoms. The goal with this work is to balance the imbalances and create normal function and health. It is not difficult (hard to do), it’s just complicated (many steps). Message me if you would like any info. It’s incredible work.


IMO getting some bloods done can be worth it if you’re experiencing long-term symptoms. I experienced some odd HR trends last year (elevated resting/exercising HR plus some pretty drastic cardiac drift) along with severe fatigue and reduced endurance, and in my case it turned out to be a pretty nasty case of anaemia- though those symptoms are common to a lot of nutritional deficiencies and other things beside.
In any case I think it’s good to rule out, and might even provide some clues to other causes,


Would you say that your RPE is also out of line with your hr? For instance that your RPE is higher than your HR would indicate it should be , when ascending a shallow hill for instance. I had this after a 10 day cold end of September / beginning of Oct.

The simple answer was to take it easy. . I reduced cycling to twice a week and accepted my fitness would drop whilst prioritising my health, keeping rides short, and not going above Z2 on a five zone HR scale… The rest of the days I’d do a walk of no more than an hour at an easy pace.

If I were in your situation, here is what I’d do: don’t do any sport now, get your two other COVID shots and look for doctors who might be able to help you. It sounds as you might still be sick or suffering from the after effects of an illness.

While you said that you don’t think it is COVID-related, the symptoms you describe could be long COVID. I’m not an MD, so take that with a grain of salt. Long COVID is hard to diagnose and can have significant impact on athletes. I wouldn’t exclude it even though you said you were tested.

Another podcast has covered the case of a doctor who was also a triathlete. Taking a walk is a challenge. Long COVID is hard to diagnose and is probably an umbrella term for several distinct illnesses.

I’ve had similar symptoms with low iron levels in the past. Might be something worth checking.

1 Like

The shot I was referring to was my booster jab, so I’m fully up-to-date on vaccination. Like you say, it does feel like the most obvious cause is the illness I had before and over Christmas - it’s just very unusual for me not to make a full recovery once the acute symptoms have subsided.

1 Like

Sorry, I misread your post. :+1:
Glad you are fully vaccinated. That further reduces the likelihood that you have had a serious case of Covid.

I had another look at your graphs, and it seems you are my long-lost twin brother: we both got sick just before Christmas and it lasted for a month. I went to do the doctor between Christmas and New Year, and the doctor told me “Oh, just like last year, up to the day almost.” Whatever this is, flu, cold, it stuck around with me until last week. I took an extra week to be sure I am fully cured.

Like you wrote, stress could be a contributing factor. Last year was very sucky and super stressful for me. And I think I should have perhaps cut training a little before to give myself more time to recover.

1 Like