Out of breath easily when exercising

Hi everyone, just a quick question, I have started taking T3 as well as T4 because I appear to have conversion problems. My T3 when just on 100mcu Levo was 3.2 (3.6-6.5) and T4 in top of range. TSH low at 0.02. So my endo started me on T3 - 20mg in 2 doses and dropped Levo to 50mcu. I have been taking this combo since 7th Nov and feel much better in many ways, brain fog etc but I have noticed that I seem to have less energy again like when I was first diagnosed. Its not drastic but when I play tennis I get out of breath very easily and my coach has noticed this and he says he thinks I had more stamina when I was just on T4 and certainly didn't get out of breath as quickly. I have rang the docs and they are doing me a blood test form for TSH,T4 and T3 and depending on the results perhaps I can bring forward my review with my endo which is March! Anyway, I am pretty much certain I am not hyper at all, no palps, sweating, anxiety etc and I still need 2 laxatives every day! Could the breathlessness when exercising be due to still being under medicated? Just wondered if anyone had any experience of this?

Thanks xxx

28 Replies

Queridalady, You may be a little undermedicated or your T3 level may still be low. Exercise eats up your T3. I found improvement when I added T3 but a few weeks later when I was able to increase activity I felt as if I 'hit a wall' and needed to increase T3.

ah that sounds very similar then. Thank you for your advice :) I have booked private blood test as just recently advertised on here where I can have everything checked, Vit D ferritin etc. Hopefully I will have a better picture after then.

Yes, breathlessness can be due to being undermedicated.

I will post a link below re the use of T3 and a couple of excerpts from it:-

(please note the Metabolic Treatment of Fibromyalgia is out of print):-

"If you don't have a copy of The Metabolic Treatment of Fibromyalgia, I recommend it. In the book, I describe and explain the function of thyroid hormone receptors. I also provide massive documentation for the safety and effectiveness of T3 and T4/T3 therapies as alternatives to the generally ineffective T4-replacement. You may find the documentation of value if you have occasion to defend you're practice of T4/T3 therapy.

You asked, if we don't have T4 receptors, "then why do we need T4 supplementation rather than just T3 alone?" With rare exception, we don't.

No one can rationally defend T4 supplementation on scientific grounds. I say this because the widespread use of T4 supplementation is not based on scientific studies that show it to be safer or more effective than the use of T3 alone. Instead, its widespread use is the result of a financial venture between the endocrinology specialty and corporations that profit from sales of the most commonly prescribed brands of T4".


"And finally, why do I specify that the typical patient use one full dose of non-timed-release Cytomel for life? Because extensive testing has shown that this is safe, effective, and most economical—when used within the context of our entire protocol."


Lab studies have shown that mutant, low affinity T3-receptors properly regulate gene transcription only after they're exposed to saturation amounts of T3. Under normal conditions, T3-receptors aren’t saturated, and the use of sustained-release T3 isn’t likely to provide saturation. Saturation isn’t likely to occur with sustained-release T3 because the T3 enters cells only in small amounts over an extended time. As a result, it’s not likely that large enough amounts of T3 will reach the receptors at one time to saturate them. But plain T3 in single doses enters cells in larger amounts. These larger amounts may provide the saturation needed to provoke transcription regulation by mutant T3-receptors.


I have taken T4/T3 and T3 alone in one dose and have had no side effects.

I agree with the others. I've actually collapsed on the golf course which is not as exhaustive as tennis but walking, pulling a cart and hot sun combined used up all my reserves........at least temporarily. That did not happen after increasing my hormone.

Just another experience but I still get breathless, am on T3 and definitely not under-medicated. Used to take 112mcg of T3. Previously had a good 'engine' from 20 years of outdoor sports.

Wish I knew the answer!

B12 deficiency? That's what made me breathless. Greatly improved since I started supplimenting.

Hi grey bi am getting that checked. What do you supplement with? I am using the spray at the moment

I take Jarrow's 100 mcg sublingual methylcobalamin lozenges. I also take a B complex with it to keep the Bs balanced. But best not to start supplementing until after you've had it tested.

Thanks grey but test results from the last time I was tested showed I was over-dosed. Don't take it all now but perhaps I should consider re-testing.

Might be a good idea. :)

...results often skewed when you are taking B12 ....the blood test is only a guideline and again symptoms need to be observed and treated....


You could be over and undermedicated. If a normal body secretes about 100 mcg T4 and 6-10 mcg T3, then you are only taking half the T4 you need, but twice the T3 you need! I love that you have an objective second opinion from your coach, who can verify what you're feeling. If you're healthy enough to play tennis, the answer for you may be simple: more T4 and less T3. Breathlessness can be a sign of over and undermedication, so symptoms and labs are very important. You may find this helpful: tiredthyroid.com/blog/2014/...

Hi Hifl, I was on just 100mcu Levo and had very low natural T3, falling asleep at my desk, brain fog and 2 laxatives a day :) I wanted T3 because my conversion of T4 to T3 seems less than sufficient. I am so much better on the T3, hardly any brain fog, tiredness not so bad but still very constipated (sorry for dodgy subject). I have no overactive symptoms. I went overactive slightly before my thyroid packed up and I felt very different to how I do now. anxious, jittery and fling to the loo every time I ate! I appreciate your advice. It is defiantly something that just has to be tried, adjusted and tried again. I feel that more T3 would help. When I first started taking it I would have still benefitted from the higher T4 as that stays in your system a few weeks and I wasn't out of breath so quickly. Now I guess I am feeling the affects of the 50% reduced T4. I won't give up though! Tennis is my love and as a working mum you have to have some time for yourself don't you agree? :)

Sounds similar to me I have seen improvements since taking NDT instead of Levo - the t3 must be key.

I had the problem for quite a whie, then was eventually sent for a methacholine chalenge test, at which I did miserably.. I turned out to have exercised induced asthma.... Its taken a fair bit of messing around to get my meds right, but I can run up hills now! The asthma means I can breathe in, but not out fully.... Another clue was that my heart was really pounding with exercise... This aparantly was a result of it trying to circulate non existent oxygen.

Might be worth checking out?

Interesting, thank you. I don't feel that is my issue though, breathing out is not a problem, I just run out of energy more quickly than I did before. yes my heart gets pounding but I have never ran up a hill :) it happens when I have an individual lesson which is quite intense. I will keep this in mind, thank you. Wouldn't it be great if there was a really easy answer to thyroid problems! :) For exercise induced asthma do you take steroid inhalers? I have used them in the past when I had a severe chest infection.

I take a daily steroid preventer,I have the b lue reliever spray, but for me what has made a fantastic difference has been montelukast .... A leukiotrene receptor inhibitor. Made a huge difference although am just starting my third month on them.


This is a short excerpt re exercise:


: The results of this study show that exercise performed at the anaerobic

threshold (70% of maximum heart rate, lactate level 4.59 ± 1.75 mmol/l) caused

the most prominent changes in the amount of any hormone values. While the

rate of T4, fT4, and TSH continued to rise at 90% of maximum heart rate, the rate

of T3 and fT3 started to fall.


: Maximal aerobic exercise greatly affects the level of circulating

thyroid hormones


Thank you Shaws. This would happen with people who don't have thyroid problems too I assume? I have been able to exercise without issue until the last week or two so I assume it must be to do with not having enough hormone replacement.

This thread is great, but I have a question on a slightly different take. I am properly medicated and I can work-out (jogging, kickboxing, etc.) without being normally breathless, but when I get done walking up a flight of stairs I am breathing hard and my body acts like I have just completed a marathon at anaerobic speed, and that is just one flight of stairs at normal speed. The other day, my daughter commented on it and told me to start breathing before trying to talk to her. Does anyone have a suggestion?

Hi asmile4u, I wish I had a suggestion for you. Are you always this way or just the day after you exercise? I ma glad you are medicated well to exercise. It gives me hope….I am not going to give up. I have to be able to exercise. Its really important to me :)

It always happens, but then I exercise pretty much every day. Now that I think of it, it happens even when I take a day off from exercising.


its hard to understand isn't it…..my daughter is pretty fit and well but she gets out of breath when running up the stairs but it passes very quickly.

Thanks queridalady.

I suffered a lot from breathlessness even on slight exertion and getting up stairs was like attempting an assault on the north face of the Eiger!

My TSH was supposed to be optimised but it was discovered I had a severe Vit d deficiency. After taking Vit d tablets and ditching levothyroxine for NDT I have seen huge improvements in both. I am not as good as I was in pre hypo days when I was super fit but it is not debilitating like before.

Perhaps Vit d plays an important role in aerobic fitness? My heart beats a lot faster than it did before becoming ill and I suspect this must be significant in my case.

Thanks TSH110. I am also on Vit D and NDT. I will see what the current labs say when I get them back, maybe I am not as optimal as I think. :)

Interesting I have recently upped my NDT to two grains and feel much better although I though I had cracked the dose. The breathlessness is a lot better as are my annoying heart pains so think it is the right way to have gone maybe I can drop again in the sunmmer. Let me know how you get on with results :-)

I will.

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