Thyroid UK
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Exercise intolerance

So exercise intolerance could be down to low t3

For years I have tried to exercise and alway hit the wall. I am passionate x-country skier and as it is not familiar to many of you here it is quite consuming.

Especially skate skiing you do in heart rate range 130 all the way upto 190. I can push max 186 out of myself and feel quite ok while skiing but when I am done go home and eat my snack I will start to feel tired.

Within few hours I get nauseous and eating gets hard. Might take me 2 hours to get my dinner down. I continue feeling ill and wobbly for 2 to 3 days.

Yes some of you might now say it is adrenal issues ,but the thing is that last time I had both tested same time (free t3 and adrenals )my cortisol level was fine throughout the day, healthy levels from the morning. But my ft3 was low ( 3 in range 2.5-6.5). Also high thyroglobulin.

Before that test I had six weeks period of picking berries .For example going for the swamps is quite hard, heart rate can be 140.

My resting heart rate is usually 60 and after physical stress my heart settles down pretty nice and fast.

I have been trying to exercise for years and not understood why I keep being in bad shape. Just recently I have learned this might be connected to low t3.

My dietitian said that there is no point for me to continue push myself, that I need t3 to fix this.

Later I had my ft3 tested again then it was normal ( 5.9 in range 3.5-6.5) after a month of being in bed as I had a normal flu but recovering from it took 3 weeks.

I have also learned that if I have hashimoto it causes t3 to fluctuate? Right or wrong?

I have had this for 15 years and it has not changed even tho I have tried everything in my power and I always hit the wall , sometimes so hard I end up bedridden for weeks. Especially when I try to go back to normal diet and eat gluten etc. Quit trying that.

Since nothing I do makes me feel even close to normal ,does it simply mean that without proper medication I will continue hitting the wall if I continue exercising? I have tried to take long brakes and only do yoga and stretching ,but I have skied since I was 4 :( I just love it.

Now I have been just biking twice a week. I do it slowly and walk the bike uphill. That I seem to tolerate.

I take vitamin B's , D, A, fish oils, magnesium , zinc, selenium, l-glutamine and tiny bit of iodine as I hit a huge wall using more. I eat super healthy 5 times a day.

Sorry for long posting , this all is just very confusing and just learning these things like about exercise intolerance. For years I have pushed and pushed myself thinking if I do high speed etc then I will feel better eventually as people around me seem to get so energetic after good workout.

I am skinny so I exercise to feel good. And failing...

Also I wonder if sauna is good or bad. As a true finn I go to sauna 3 times a week. I cannot stay long and often don't even warm up ,but I love sauna and skiing as I am crazy finn.

I have read it is good for adrenal glands but it might be bad as well. But about t3/hashimoto did not find much.

Sorry again.

Did I mention it many times enough I love skiing? :P

13 Replies

Justiina, I'm wondering whether you love skiing ;)

Hashi's attacks cause TSH, FT4 and FT3 fluctuations. When the thyroid is attacked cells are killed off and dump hormone into the blood stream which can cause hyper feelings and if tested at that time may also show elevated FT4 or FT3. After an attack the thyroid may atrophy and be unable to produce the same amount of hormone as previously so you feel hyper.

Exercise and exertion burn up T3 and may take days to restore, hence the post exertion fatigue for several days.

I've no idea whether Sauna is a good or bad idea. I can't see why it should affect thyroid levels but a cold plunge afterwards might be too much of a shock for hypothyroid patients already suffering low body temperature and may be difficult to recover from.


Thanks. So it could indeed be about low t3. That is sort of relieving that there can be actual reason and no amount of exercising / torturing myself will fix the issue.

Yup I can feel cold before sauna, in the sauna and hours after sauna so I go to bed clothes on and sleep under two blankets. I can also get really short of breath and my heart is racing fast and I have to lay down after sauna.

Sometimes going sauna feels good and I even sweat. Oh well maybe less sauna would help.

Over here in Finland we say if you are feeling ill you will die if going to sauna, tar nor alcohol helps you :D

I guess that is why going to sauna sticks so hard. If you cannot tolerate sauna you are weirdo.



How wonderful to be able to ski so well. I tried it a few times and was always so rubbish. lol.

I don't know where I read this but understood it that our muscles need a vital supply of adequate thyroid hormones especially for those slow- twitch muscles that you need for prolonged effort.

T3 is actively transported into slow twitch muscles and so if your T3 levels are insufficient, your exercise staying power and muscle strength will suffer.

Are you medicating on thyroid meds?



I do feel I have very little muscle strength compared to fact how much I try to keep it up! At grocery store I sometimes have to use shopping cart to be able to walk and be able to lean on something when standing in the line.

Not medicated yet. Finding a doctor over here is hard and getting re-tested even harder.


I am an ultra runner and last year was having problems with fatigue. I take levothyroxine but had my iron levels tested and these were low. Since taking liquid iron - floravital I've felt much better.

The research indicates that it takes much longer for athletes who have an underactive thyroid to recover from training and you can get symptoms of overtraining very quickly

I'd love to go cross country skiing 😀 I've only ever done done hill skiing 🎿


I cannot get my iron levels properly tested, only haemoglobin which is on high end for me. Always been regardless heavy periods.

I used iron boost spray for a moment last spring and I felt better but was denied to use it because of high haemoglobin still refused to get proper iron tests.

Over here many runners ski during the winter. Not because they cannot run but because it is excellent way to train.

X country is so versatile. Both styles classic and skating has their own benefits. Classic you can do with lower power and it is easy for everyone.

Skating requires a lot of strength from you midsection as the movement comes from there. While skating you use muscles you barely use otherwise and it increases strength of core muscles. It also requires good balance as well it increases it during the time.

I just love love love it :D I hope you get to try. It is not only about exercising. During the pretty days it is just nice to enjoy the weather skiing slowly and atop for a snack.


Not sure if this applies to you, but this article just happened to be in my inbox this morning.

Why exercise magnifies exhaustion for chronic fatigue syndrome patients:


And, of course, any form of exercise uses up your T3, so if you haven't got enough to start with, it's not surprising that it takes you a long time to recover.


Guess what, I figured that what you say, unfortunately,is the way it is :( It sucks as I dont want to give up on my hobbies, but then again its not worth to rest for a week to be able to ski a bit and rest for another week. Sorta limits my life big time. But tell that to my head... I am so freaking stubborn and I would deny I am ill even though I would be half in grave.


Hi I saw your post yesterday. I have hashis and struggle with cardio exercise but manage to stay well with yoga pilates and good old fashioned walking. I love cardio at the time and I feel great but then it takes a few days to recover and I feel like Ice been hit by a train. I've been better since I increase carbs in line with activity to be honest. Anyway have you thought about writing to one of your universities in Finland. Maybe where they are doing research on exercise physiology, to see if they have any ideas or maybe they could use you as a guineapig and do some tests before and after. You never know there may be a postgrad student needing a project. Just a thought.


well my friend has connections to one of the universities so I could ask her if she knows anything about research like that going on!

I read your earlier posts and I noticed you feel worse during your periods and week after. I feel the best during my periods lol. I do bleed for 7 days , but then I have most energy. Time of month I wait for! Then I feel exercising is easier and I feel less fatigued.

I have now decided to do only yoga, walking and slow biking to maintain the physical fitness until my health issues have been properly taken care of.


I have been on T3 for about six weeks now and the difference when I exercise is profound, I always had to do the low impact version of anything as my knees, hips and back hurt too much and my muscles were not strong enough, now I can actually bounce on my toes, my bones don't hurt and I can push myself a lot harder, my recovery time is much quicker too - so don't give up, if you get the right treatment you can get your life back 😊


So nice it worked for you :) I hope one day I get to say the same!


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