Interesting study discussing the effects of high intensity interval training on :
conversion of T4 to T3 .
conversion of T4 to rT3 .
and CORTISOL.
~ Study is done on healthy fit subjects, so obviously we must assume their healthy functioning thyroid gland also had some involvement in proceedings, so we can't apply any of it directly to people without a properly functioning thyroid.
Thyroid hormonal responses to intensive interval versus steady-state endurance exercise sessions
Anthony C. Hackney/Ashley Kallman/Karen P. Hosick/Daniela A. Rubin/Claudio L. Battaglini
(Endocrine Section - Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina /Department of Kinesiology, California State University Fullerton, Fullerton,California, USA)
If only endocrinologists were as interested in our T3 as this lot of sports researchers are.
"Objective: To compare the thyroid hormonal responses to high-intensity interval exercise
(IE) and steady-state endurance exercise (SEE) in highly trained males (n=15).
Design:
The IE session consisted of repeated periods of 90-seconds treadmill running at 100-110%
VO2max and 90-seconds active recovery at 40% VO2max for 42-47 minutes.
The SEE session was a 45-minute run at 60-65% VO2max. Total work output was equal for each session.
A 45-minute supine rest control session (CON) was also performed.
Pre-session (PRE), immediate post session (POST), and 12-hours post-session (12POST) blood samples were collected and used to determine free (f) T4, fT3, reverse (r) T3, and cortisol levels. Results:
All PRE hormone levels were within clinical norms and did not differ significantly between sessions.
All POST IE and SEE hormone levels were significantly elevated compared to POST CON (p<0.001).
At 12POST, no significant differences between CON and SEE hormonal levels were observed;
however, fT3 was significantly reduced and rT3 was significantly elevated in 12POST IE compared to 12POST SEE and CON (p=0.022).
For IE, at 12POST a negative correlation ..was found between fT3 and rT3.
Also, for IE, a positive correlation .. between cortisol POST and rT3 12POST was noted,
and a negative correlation .. between cortisol POST and fT3 12POST.
Conclusion:
IE results in a suppressed peripheral conversion of T4 to T3 implying that a longer recovery period is necessary for hormonal levels to return to normal following IE compared to SEE.
These findings are useful in the implementation of training regimens relative to recovery needs and prevention of over-reaching - overtraining."
I wonder if this was why I’d go freezing cold after running. It was a lot quicker to take effect than 12 hours tho, I was untreated back then probably mildly hyperthyroid most of the time - terrible headaches afterwards too and my vest would be covered in salt deposits from all the sweating .
All much better now, but also I’m a lot slower runner than back then, which might be significant.
HiI used to get exactly the same thing. Headaches and couldn't warm up. Not such a problem now but I still can't run the way I'd like. I'd love to pop out and do 8 or 9 miles and go about my day again but that's not nearly possible. Can't even do 3 miles. Do you manage to run? When I try my heart rate still rockets!!!
I share your frustration. I used to run 6-8 miles three times a week and loved it. I can finally do 3+trail miles but it has taken years and fits and starts working around dose changes and symptoms, to get where I am. We are all different but for me training very carefully to heart rate brought it down as my fitness improved. I have had to learn patience-not my strong point!! This post has made me wonder if a bit more T3 may help after a run…?
HiI've been trying over the last few years to run again. It goes in fits and starts. In my head I think I can do it as I feel better after adding t3 at the start of last year but when I actually try to run I still have that feeling of trudging against something. Heavy legs and slow moving. Also I feel kind of hungover after. That probably could be resolved with a bit extra t3. Can you do the pace you used to do and feel "light"? I miss running. I used to feel cleansed after a run and I'd love to get back to it. Sorry for the quizzing but I'm really interested that you've got back to it!
( Edit .. sorry BiscuitBaby , i just realised this was to flitter-maus not me )
.. actually i was never 'into it'.. always disliked running,, so i only do it if something big and hairy is chasing me. But i used to do lots of other intense muscular stuff for hours at a time .. no, i've never got this ability back on Levo .. i've had to learn to pace myself, which has been very hard .. it eventually required a 'personality transplant' . I now saw logs up in spurts of about 10 seconds and then change arms, and stop before i want to . It takes me 5 days to do something that i would have once done in an afternoon.
I can still do flat out which always felt really hard and it still does but it’s a lot slower flat out than it was. I agree the lighter feeling is lacking generally at slower pacing tho I do get short bursts of it sometimes often when my heart rate changes gear upwards. I still enjoy running nevertheless
Still working it out 3 years in and 1 with T3! It has also been fits and starts. No I don’t have the stamina for distance or the pace I used to but I’m not ready to rule it out yet-I’m stubborn🙃! I certainly don’t have that lovely light feeling back and my runs are mostly trudge but less so as I’m building up. I have had moments of that familiar running glee though.
I can’t say I’ve felt that hungover feeling after but can be a bit hypo for a day or so after but not always🤷♀️I did add a bit more T3 to my afternoon dose on running days which seems to help but it’s very early days.
When I started back this is how I did it:
Walking only for a month then walk /run for a month, building up to full runs very gradually, upping the distance slowly and totally ignoring my times!! Also I never let my heart rate go out of aerobic on my Garmin for the first month or so then allowed myself very short bursts at higher heart rates as I went along. My heart rate has dropped as I’ve got fitter but doing very little did make it shoot up over the first months. Alongside this I’ve done Pilates and strength training a few times a week.
The difficult thing has been the mental adjustment from having a body I could push, train and challenge as much as I liked, whenever I wanted to a body that wants to write its own running rules! How very dare it!!! We are making peace with one another and running progress but oh so slowly.
As is often said on here we are all different -this works for me but your body may need something different. What I can say is that though I always hoped I’d get back to running the reality of me even 6months ago made it seem almost impossible. Keep hoping, keep trying, be patient and kind to yourself🙂
Thank you. Yes I have added strength training. Not that I see any muscle definition 😕 but I keep trying. I've learnt to be kinder to myself but it's still hard. Not being able to keep up my fitness has been the hardest thing for me. Also the physical change in how it looks. I never really put on weight. Not a huge amount anyway but I have zero definition. My 6 pack is across the way Not up and down 😅. Its just frustrating! Thank you for your advice.
it’s been a rocky running road for me! I do still manage, can do up to 10k think I’d struggle with a half marathon now - I used to do them loads. I have Achilles problems which have marred my efforts and means I have to limit mileage. I do better on many shorter runs rather than fewer long ines. My times have plummeted 5k is now 10 minutes slower than it was and is not great for my age either so it isn’t just the aging process holding me back. My heart has been very bizarre it used to rapidly rise into c 197 bpm which I could easily hold for a half marathon, with it hitting c 210 over the line. Now it will not rise for ages (on an 5k which I now do regularly) and it’s much harder to hold it at a set bpm where before I could choose to keep it at a certain bpm within one beat. It can rise to over 200 and I have to try and hold it back and despite 212 being the highest reading I had ever had on the finish line it went to 218 recently which was a tad alarming, but I am still here 🤣🤣🤣 there’s a lot of heart disease in the family and I think mine is just slowly degenerating getting less predictable and faster as it has to work much harder to get me going at a reasonable pace which is a lot slower than it used to be got the same effort. Resting it was around 50 before I got diagnosed with thyroid problems but it’s over 70bpm so it’s doing a lot more work just to keep me basically ticking over. I take heart in the fact that at least I am still running even if it’s become more plod than fast paced!!
have you tried run/walk it really helps to slow the heart rate and build up your endurance /fitness to run, gradually. These super long distance runners use it a lot as a training tool. I found it really helpful coming back from being so ill with my thyroid
I can't sustain running. I have to do an element of walk/run. I have a route that I know is about 3 miles but I just can't get round it all in one go. 10k is so far away. I'd live to try ndt to see if that helped. I still feel I have some residual symptoms but I'm lucky they prescribe my t3 on the nhs and they are more focused on specific regimes rather than symptoms. My times are rubbish. I'm sure I hear my garmin laughing!!!
perhaps you just need more time to recover and get optimised. It’s not good to over do it until you feel up to it. Sounds like you’re heading in the right direction 👍🏽
This makes perfect sense of my day to day findings! No lycra involvement
I'm able to bimble around quite happily and generally walk 5 -10 miles a day.... If I walk too fast or get carried away and think hmm I'm feeling well today how about a little jog = no bimbling for a few days
I suppose in our unnatural dosing regimes this will always be the case, you use it = you lose it.
My next experiment will be to try a little jog, assisted by adrenal supplement and a following shot of T3 to see if I'm still floored...
Post exertional dosing seems eminently sensible to avoid the malaise and more inline with mimicking a more natural recovery response?
(I'm getting a red wiggly line under 'bimble'?? An excellent descriptive oh so British word)
It does make so much sense to make slight adjustments between more and less vigorous days when more reliant on T3 rather than T4 when you are a bad converter. Much as you would with the amount of calories necessary for differing workloads
Hi Tatty, 🤗 this is very interesting as I have noted since being medicated as long as I pace myself I can go along quite well, but if I over exert myself- I pay for it in ways far greater than before being on levo. I’ve lost my ‘overdrive’. I also consider the healthy thyroid responsive, fine tuned, kicking into action, supply on demand. Yes observable fluctuations when exercising, but the thyroid works hard to recover the steady state. We hypos have our little white pills and a finite amount of thyroid hormone. Without the T3 being directly produced by the thyroid alongside the T4, those of us on mono are missing part of the puzzle. Someone said today as a result of delay in diagnosis and treatment do we perceive any improvement on our previous state to be feeling better? It’s a good point…..
I have reached a very comfortable place, physically, mentally but I do miss my overdrive sometimes.
( i used to have a 1970's ambulance that had an overdrive 'gear'...that broke too~ engine was much less 'comfortable' on the motorway afterwards, used a shed load more petrol, as fixed to it's gear ratios it had lost the capacity to 'run free')
This study can't differentiate between how much of the fT4/fT3 alteration is due to affects on deiodinase conversion , how much is due to thyroidal production, and how much is something else .. and of course 'what is in the blood' at a particular time point is not necessarily what is 'in the cells'.
I suspect ?? ( diogenes ? any thoughts would be much appreciated)...... that the initial rise in T4/T3 (seen at the end of exercise period) is not due to thyroid producing more during the exercise , as it's hard to imagine TSH rising fast enough during a 45 minute run to have time to produce this increase in T4/T3 from thyroidal 'production' ??
Does increased blood flow through the thyroid during intense exercise increase the amount of 'ready made' T4 /T3 that is picked up on it's way through perhaps ???
Or is this initial rise in fT4 / fT3 levels mainly the result of changes in peripheral conversion ????
The sort of testing in this study is what i hoped would be available when i was referred to the CF/ ME service on developing Post Exertional Malaise (PEM) after being on Levo for a couple of years .... i assumed they would be interested in looking into clinical reasons for ' next day' appearance of PEM. ( wrong ~ their interest in looking into anything clinical , or thyroid, was "Zilch") .
I get this the following morning after i've 'overdone it' (physical & mental 'crash' and symptoms like a Hangover lasting at least 24 / 36 hours, often longer )...... and interestingly the same thing happens ( but worse) the day after i've been emotionally challenged by a situation of the type that triggers 'fight or flight'..... leads me to think 'adrenaline' is involved somehow ~ someone once explained ME to me as "like being allergic to adrenaline" .. a very apt description .
I would REALLY like to see this study repeated to include a group of patients taking Levo who suffer from PEM, and with extended blood sampling to see what actually happens between 12 hours and 72 hours. (and i'd happily go on a treadmill to take part, even though it would mess me up)
If it takes healthy people more than 12 hours but less than 72 to replenish the fT4/fT3 levels in their blood .. then i want to know how long it takes people who's thyroid is effectively 'off'.
It would be interesting to know if TSH can change in 45 mins of running to alter the t3 t4 balance. I can’t see why it could not if it’s responding to changes dynamically in free t3 blood levels as they happen. Otherwise why have this TSH feedback mechanism in place? Surely changes must be happening every second of the day in healthy individuals with a fully functioning thyroid to deal with any eventualities encountered.
it's not very often we find ourselves complaining someone didn't measure TSH , but it would have been very interesting to see what/ if any TSH changes happened here.
But i struggle to believe TSH can react within 45 mins ,...see the TSH levels on these 3 patients Levothyroxine absorption tests... ncbi.nlm.nih.gov/pmc/articl...
1000mcg Levo in one dose and bloods done at 1 hr and 2 hrs .. TSH barely moves in any of them by the 2 hour point . yet 2 hours was long enough for the massive dose of Levo to show in the increased fT4 results .
~~~~~~~~~~~~~~~~
I think i've seen another set of absorption test results that did show a marked TSH change over a longer period , but can't remember how much / how many hours ...typical .. i can't find it now i want it .
shows TSH IS capable of FALLING very fast within an hour when it is very high at the start of the test (unlike those previous 3 ~ where TSH was very low at start if test and it barely moved at all ) in this test TSH was 430 and fell to 370 at 1 hour after ingesting 1000mcg Levo.
LOL! Being a super fast reactor to all medications I bet mine could change in a nanosecond! It did manage zero to 110 in a week in its final death throes! Gobsmacked it can go as high as 430 in some poor devils. I’d find I could suddenly run 8 miles with zero effort after feeling utterly wiped out for ages. It was doing somersaults at the end. The heart pains were something else. I think I needed 1000mcg of Levo not the measily 25mcg I was kept on for three months. If the heart could withstand those vacillations surely it could have coped with 50mcg starter dose and more timely titration there on in.
I propose something quite disturbing. And that is that the excessive activity has caused a temporary nonthyroidal illness syndrome - ie it has the potential to do some damage. If rT3 rises at the expense of FT3, then this proposal looks convincing. You can do yourself damage by doing too much.
Anecdotally, this is what I did. I ran a half marathon in the November and I'm quite certain it's what pushed my thyroid into warp-speed destruction.
I had a 'mini-breakdown' shortly after the halfer. My mental and physical health totally bottomed out. 6 months later my TSH had finally risen out of range significantly enough to get my diagnosis.
That would make sense. I found after very long runs my voice used to go really deep for a couple of days. I bet that was down to thyroid hormones going wrong because it was too much and it was already struggling. Later on I sounded like a darn darlek all the time with no nuances of expression in my voice at all. It has recovered thankfully. I don’t get it on thyroid hormone therapy.
I find this really interesting. I used to run many years ago, mostly long distance and cross-country. The thought of doing anything that vaguely resembles running now seems very alien to me and not achievable as I can barely manage a walk.
Hopefully as I become more optimally treated I'll feel less heavy legged and worn out.
There is so much to learn about managing thyroid conditions and timing of taking hormones.
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low FTx levels but severely suppressed TSH
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